LARGER VIEW of a heating boiler cad cell relay switchHeating System Zone Valve Repair FAQs
Zone Valve Diagnostic FAQs #1

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Hot water heating system zone valve diagnosis & repair:

Frequently-asked questions about heating zone valves on hot water (hydronic) heating systems.

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Hot Water Heating System Zone Valve Diagnostic FAQs

Honeywell heating zone valve

These hot water heating zone valve questions & answers were posted originally at ZONE VALVES, HEATING

Question: After adding a third zone valve one of my other heating zones stopped working

I have a two zone heating system with two thermostats and one circulator. I recently added a third zone for my basement. I have not wired in the zone valve and T-stat yet for the new zone. Since adding my third (non active) zone my 2nd floor zone has stopped working.

If I manually open the valve then when the circulator starts to heat the first floor it pushes water around the second floor as well. I have tried testing voltages across terminals 1 and 2 and 2 and 3 but I get no readings either on the bad zone or the good one.

I would have expected to see 24V on at least the working zone but I don't. Why is that ?

I have checked the connections to the thermostats and transformer and all seem secure.

Also I noticed that my transformer doesn't appear to be sending out power - do I need to be there when something else tells it to send out power or is it constant. If it's constant and I have no power then how is my system working at all ?

Could it be I just fried my zone 2 thermostat, how could I test for that ?
I have bled the bad zone countless times and I am sure I have purged all of the air.

Any suggestions would be appreciated. - Will 11/13/11



Since you never wired up the new zone valve, and presuming you did not change the existing wiring to the existing zone valves and circulator and thermostats, it does not sound like a wiring or control problem. Therefore you need to look for a different problem.

When you open the new valve manually, IF one of the other zones is also calling for heat, then hot water will circulate through both the zone calling for heat AND the other zone valve that you opened manually.

I agree that you ought to be seeing voltage from the transformer - that's what sends power to the zone valves as well as the thermostat. I'd look for an open wire connection or a bad transformer.

Reader follow-up:

It wound up being an airlock. I just kept purging and purging and eventually got it.

I have another quick question. I used PEX and SharkBites for the whole system, however, the PEX I used was the type without the oxygen barrier. I’m told that this will cause my boiler to rust. What do you know about this, anything ?

I don’t want to have to get another roll of PEX with the barrier and tear out what I did if I don’t need to, On the other hand I don’t want an indoor pool.



Will, when you added the new zone valve to the heating system piping, the operation of cutting the heat distribution piping and soldering in the new zone valve could have introduced air into the heating system. If you didn't bleed that air out or provide an automatic air bleeder in a location that would do that for you, your system could be airbound.

To check for, diagnose, and fix that problem, see AIRBOUND HEAT SYSTEM REPAIR by WATER FEED VALVE if you need to address this problem again.


Question: zone valve makes clicking noise when it is fully open and gear motor continues to run

Eric zone valve vt2343g13a02a works good but when in the open position it keeps clicking like the gear motor continues to run and the gear is clicking on the last tooth of the actuator or something???? - Ken 11/23/11


Ken a zone valve that keeps clicking suggests to me that either

the zone valve motor gears have become stripped or

the valve assembly is jammed and is not opening fully - the motor is unable to turn the valve to the fully open position, it is not reaching its "end switch" position, so it keeps trying to open the valve. Most likely you need to replace the unit.

Question: upstairs heating zone won't turn on or doesn't receive heat

My upstairs heating zone is not turning on this year. I have checked the setting on the Electronic Aquastat L 7124/L7148 and can not find anything amiss. What might I be missing? - Lisa 12/30/11



If your non-working heating zone has its own circulator pump, the service tech will check that the circulator responds to the thermostat on a call for heat. If not, check the thermostat, thermostat wiring, check for power at the circulator, check the separate circulator relay if your system uses one, then check the pump itself.

If the circulator is running, the boiler is hot, but heat is not delivered to one zone, your heating zone could be air-bound.


If the heating circulator pump runs but never causes the boiler itself to turn on and re-heat water, the primary control aquastat could have a burned-out primary or secondary circulator control circuit.

Keep us posted, what you find will help others.

Question: two zone boiler, single circulator pump replaced, now one zone doesn't heat

I have a two zone boiler with a single circulator pump that was recently replaced. I'm now having trouble with circulation for one of my zones. I think its the zone valve itself though when the thermostat calls for heat I see the valve adjust and I can also set the arm into manual.

My question is, is there a way test further if the valve is faulty. My instincts say if I can set the valve and it responds to the thermostat then its not faulty. Thanks - Chris 2/12/12


Chris, as the circulator pump is running (else your working zone would also be cold) I suspect that either the zone valve is stuck shut or that zone is air bound. You are right that setting the room thermostat up above room temperature should cause the valve to open, but if the zone valve itself is jammed or if the zone is air bound you won't get heat.

Question: Taco zone control valves 571, 573 led to short heating cycles

I Installed two Taco zone controls 571 & 573, and now I have short heating on cycles. I never had this problem before, for 47 years. I had to replace the zone controls because the old zone valves started to stick, but they were not Taco brand. I replace the thermostat with a Honeywell TH3000 series, but that didn't solve the problem. - Anon



When the thermostat calls for heat the zone valve opens and the circulator starts pumping. It is the temperature of the water in the boiler that turns the burner on and off. By short cycling I presume you're meaning that the boiler stays on for just a short time, turns off, then quickly turns back on.

Sometimes this is a normal event, for example when the first surge of cold water from zone 1 hits the boiler and turns it on, the boiler's burner may be able to heat up the boiler quickly and shut it off; the boiler would stay off for a while. But when zone 2 then opens and sends a new surge of cold water into the boiler it will start again quickly in response to that new temperature drop.

However, because it normally takes some time for the heating zones to actually satisfy the thermostat, once both zones are running your boiler should return to normal run times. If it doesn't I suspect a sensor or control problem at the boiler.

Question: boiler temperatures are too high and the circulator pump malfunctions

Our burner keeps getting hotter than 190 degrees and the circulator has been replaced six times in the last four months. Our aquastat has also been replaced. We had a double then a triple installed. The aquastat currently in place is an electronic hydrostat. The wiring to the burner has been replaced. What can be causing the Taco circulator to malfunction or the burner to get hotter than the settings on the aquastat? - Andrew D'Agostino 4/25/12


Andrew, 6 circulators in 4 months sounds quite odd and as if no one found the real problem. I have seen repeat circulator failures when the tech replaced just the motor or pump but left a bent or worn support that torqued against the shaft bearing and ruined the replacement. If course, limited to no onsite assessment i am not sure what's going on.

If an aquastat us not shutting off the burner at the HI limit I suspect an improper installation, such as poor thermal contact in the sensor well or mis-wiring.

Perhaps you should ask the service manager for more expert help.

Question: Two zone valves on boiler, but one won't go on unless the other one is also on

I have 2 zone valves on my boiler and zone1 will not go on if zone2 is not on. When zone 2 is on everything works good.Is this a bad valve or a wiring issue. - Frank 10/8/2012


Frank, if you mean that the zone valve itself does not operate or it's end switch does not turn on the boiler unless another zone valve is on then it's likely to be a wiring problem. Watch out for the case of two different zone valve brands - sometimes their wiring hookup details are different.

Question: zone valve installation diagram

I need diagram for install zone valve - Manuel 10/8/12


Manuel, we don't know if you're asking about piping routing, zone valve location, or zone valve electrical hookup. The wiring for zone valves varies slightly among brands and models - and will be shown in several options on the instructions that came with your zone valve. As you are installing a valve, look in the box.

I know, some fellows use the instructions to kneel on during work at the boiler, rather than reading materials. If you've lost the instructions, give us the zone valve brand and model and we (or you) can obtain the detailed instructions from the manufacturer.

Typically there are four wires at the zone valve.

Two wires connect from the room thermostat to tell the zone valve to open or close in response to room temperature. They may be marked T1 and T2. Two other wires connect the zone valve end-switch (a switch that closes to make the circuit when the zone valve itself is fully open or shut) to the circulator relay. Those may be labeled C1 and C2.

Question: why should my bathroom heating zone always be calling for heat?

I am not sure if bathroom zone should always call for heat when no other zones ever call for heat unless I turn them up - Steve 10/12/12


Steve, Properly wired each zone normally calls for heat independently.

If your bathroom zone is always calling for heat, check for a short circuit in its thermostat wires, or for a defective thermostat, or a thermostat set higher than the room temperature.

Question: indirect fired water heater is making water that is too hot

We have an oil fired boiler situated on the ground floor which supplies heating to our radiators and also supplies hot water to our bathrooms and basins from a hot water tank situated in a cupboard on our landing. Recently the actuator to the hot water system seemed to fail as the water was becoming very hot irrespective of whether the hot water was on or off at the control panel situated by the boiler as long as the central heating was set at "on".

I replaced the actuator to the hot water and it seemed to be ok for a while but then the problem recurred Can you advise please? The only thing I can think of is that recently our son in law opened all the valves to drain the hot water so that he could re-washer a hot tap. This may or not be relevant though. - Roger Cotton 10/28/2012



If the indirect fired water heater you describe is making water too hot, check it's thermostat settings first, then check for wrong replacement control thermostat or a sensor that is coated with mineral deposits and is not properly sensing temperature.

Question: 100 Series gas boiler is not heating all parts of the house

Have a 100 series gas boiler. Part of the house gets heat but part of the house isn't getting heat. Worked for about a week and stop working and cant figure out the problem. - Brand 11/4/12



I would check for a thermostat not calling for heat, a zone valve not operating, a circulator not running, or an air bound system. Often it helps to feel the distribution piping to see where pipes are hot, and not.

Question: After service following flooding from Hurricane Sandy, our boiler keeps running almost constantly

After an annual maintenance visit I noted very hot water and the furnace running almost constantly. They replaced zone valves and charged me. I recently evacuated my house to avoid hurricane sandy. When I left I turned off oil burner and and turned off thermostat.

when I returned home -and turned oil burner switch back on i got hot water but no (baseboard) heat.

Technicians replaced zone valves AGAIN and said it was due to power failure. Does this make sense?

I would truly appreciate your opinion. - Zone Valve Issue 11/14/12


Zone Valve Issue:

If your zone valves were flooded they'd likely be destroyed.

Since zone valves usually run off of a 24V transformer, if there were a power surge following a power failure, perhaps a transformer might be damaged, but I don't know how the zone valve itself would see the power surge nor power failure. But none of us knows it all. See if you can get your heating service people to be more explicit about exactly what component failed and how a power loss would cause that failure, and post the follow-up here for our research.

Also if you can let me know the brand and model of your zone valves we could check with the manufacturer too.

Don't assume malfeasance on the part of your heating people - often the service tech knows what s/he is doing but was not an English major in school.

Question: how do I wire one zone valve to cause another one to turn on?

How do you wire one zone valve to another. One controls the other? - Joe 11/22/2012



I've never tried wiring zone valves in series,
but in effect, if you want two zone valves to open at the same time in response to the same thermostat, you can wire them in parallel - that is, the thermostat wires that talk to Zone Valve #1 are also carried to Zone Valve #2 and connected at the same point.

Question: Our upstairs zone makes noise as if it is opening, and the boiler turns on, but we don't get any heat

I have 2 zones to my furnace basement zone works , but the zone upstairs makes noises as if its working furnace kicks on (2 mins) but no hot water going thru pipes ... Help! - Terri 11/26/12


Take a look at the zone valve diagnostic steps listed at ZONE VALVES, HEATING

If your zone valve is actually opening and the circulator is running but the zone doesn't receive heat, it may be air bound.


On the other hand, the zone valve motor may be making noises but the valve may be stuck and need replacement.

Question: trouble wiring up different zone valve controller brands together

Hi, I have a HE II Weil McClain nat gas boiler. A few years back I converted about 1/4-1/3 or my house into hydronic radiant floor heat running off same zone as the baseboard. The guy who sweated the tubes and zoned it out has never come back to hook up the zone controller.

Someone else came out the other day to hook it up. I have a TACO SR502 2-zone controller and this person purchased a Honeywell L6006C 1018 aquastat controller. I am thinking he purchased the wrong aqua stat. He said the whole system will never allow for 2 zones.

I spoke w/techs @both TACO and WeilMcClain who, both said, I can have my floor heat operate separately from the BB units. (I do have 2 thermostats). Can you shed a little light on this, please? Thanks, - T.B. 10/27/2013

Reply: known problem; check with the manufacturer, the wiring diagram, or send us more details

Absolutely, if properly wired, you can take a single loop of hot water baseboard heat and subdivide it, giving each sub-loop its own thermostat and zone control valve.

I have moved the details of this discussion to a new article ZONE VALVE WIRING where I give specific wiring examples for multiple zone valve installation and where I give more details about how we wire up "incompatible" brands of zone valves on the same heating system.

Question: water flow stops in one zone

(Jan 21, 2014) Steve said:

Three zone system and two work fine. For the third (upper level), when not calling for heat, water circulates ... when thermostat calls for heat, water stops flowing. What would cause that?



Question: Do the primary (central heating) and secondary (hot water) circuits use the same water ?

(Jan 27, 2014) richard lewis said:

Do the primary (central heating) and secondary (hot water) circuits use the same water ? If so, can I use the electric immersion heater to heat the water within the calorifier / heating coil via the hot water in the tank and pump this around the radiators ?

I ask because we have a holiday home with a pressurised oil fired central heating which sometimes cuts out for no reason. If this were to happen when the house was unoccupied there would be a risk of freezing. If I set the immersion to cut in when the water was cold would the heat transferred to the heating coil via the hot water in the tank get pumped around the radiators if the zone valves were open and the pump was on. I know that this wouldn't be a very efficient propcess but may just prevent the pipes from freezing if the boiler had tripped out ?

thank you



No Richard. The physical water inside a heating boiler is not the same water as used for domestic washing and bathing, withe the sole, unusual and not recommended occasional small heating load design in which someone tries to use a domestic water heater also for building heating.

If your heat is cutting out for "no reason" I am guessing more likely there is a reason, possibly one having to do with safety, but that has not yet been properly diagnosed.

No you do not want to cross connect your home heating system with your hot water system. I realize we could figure out a way to do it, but you are cross-contaminating both systems.

Question: normally-open zone valves: power required to keep valve open

(Feb 3, 2014) Dennis B. Hoff said:

What I understand is with the normally open valve power is required continuously keep the valve closed. I think that this could cause extra heat build up in the motor and cause premature failure along with more power usage.

The normally closed valve only uses power to open the valve when heat is called for. The application that we have is residential, but was originally installed when the house was built 29 years ago. It's a good system but we are trying to improve costs and new procedures develop with time. There are no special heating needs or requirements.

Thanks for all of the information it will help us in making a decision. Probably one thermostats at a time.



Dennis: thanks for the follow-up. keep us posted. As I noted, unless the valve mechanism itself is damaged, you can just change the power head - leaving the actual valve assembly in place. Quoting the product literature:

Easy servicing because the entire powerhead assembly can be replaced without removing valve body from line. Optional accessory fittings can be provided to facilitate convenient removal of the entire zone valve unit. - op cit.

When changing the thermostat, there are some models that can be wired to operate either type of zone valve: normally closed or normally open. An example we're looking at is the Honeywell FocusPro TH6110D programmable thermostat - it's quite versatile.

It's not clear to me that the added heat from the 40VA transformer wiring that powers this zone valve would normally be sufficient to contribute to the product's failure in the field. The temperatures of the circulating hot water are, in my OPINION more likely to be a factor in zone valve life.

Watch out: for conditions that could contribute to zone valve failure.

[The Honeywell Honeywell V8043 series zone valve is ] suitable for glycol/water mix up to 50:50 use in closed hydronic systems. Not for use with oxygenated water, potable water or steam. Use this valve in hydronic systems which DO NOT contain dissolved oxygen in the system water. The dissolved oxygen, which is found in systems that have a frequent source of make-up water, causes the rubber plug inside the valve to deteriorate and eventually fail. - op cit.


Watch out: however, for wiring errors, short circuits, or a misbehaving low voltage transformer. Those defects could contribute to zone valve failure, as might corrosive or mineral-laden water in more rare cases. See CHEMICAL TREATMENTS, BOILER

Question: small boiler leak, will stop-leak products clog the zone valve?

(Feb 4, 2014) Ray said:

I have had a small boiler leak, I put a quart of Hercules Sealer in my boiler,It stopped the small leak, now it seams like my zone valves (automag) are not opening when the zone calls for heat, or maybe my automatic air valves on my baseboard heat trim may be plugged,Should I now drain my system to clean out excess sealer, what do you suggest?


Ray, I'm researching the Hercules Stop-Leak product - so far don't see a warning about clogs.

I would try two things just to start:

1. if your zone valves have a manual-open position and latch, use that to move the zone valve open - at least you'll have heat, and moving the valve (rarely) might free it up

2. try (with the heating system cooled down) opening and cleaning a manual air bleeder if that's what you've got; if you've got only the float type air bleeder devices, indeed the bottom opening or float could be stuck. Those are inexpensive devices; I'd remove an old one, allow a small amount of boiler water (ounces) to blow out the mount opening, and install a new one.

3. depending on where the boiler leak was, is it possible your system is air bound? If so we can point you to diagnosing and fixing that problem.

I'm collecting this discussion along with added information at our article titled

Heating Boiler Chemicals, Treatments, Leak-Stop

(which you should be able to find by searching InspectApedia for that title.

Question: number of zone valves per thermostat?

(Mar 5, 2014) tej said:

how many zonal valves for floor heating can be connected to one room thermostat



Interesting question. Normally one thermostat controls one heating zone and is connected to one zone valve. But as the thermostat is basically an on-off switch, indeed we've discussed with readers the successful combining of more than one zone valve switched by the same thermostat.

Watch Out: to avoid overloading the tt or its power or circuit, check the zone valve wiring instructions. For switching multiple zone valves with one thermostat you may need to have the thermostat control a switching relay that in turn switches the gang of multiple zones. A typical switching relay such as the Taco SR502 - 506 can switch 4 zone valves or more.

To find out more about the switching relay I cited contact

Taco Inc., 1160 Cranston Street, Cranston, RI 02920 Telephone: (401) 942-8000 FAX: (401) 942-2360 - USA
or if you are in Canada contact
TACO (Canada), Ltd., 8450 Lawson Road, Unit #3, Milton, Ontario L9T 0J8. Telephone: 905/564-9422. FAX: 905/564-9436.

The company's website is at

Question: when thermostat kicks on, the manual switch on valve does not move

(Mar 7, 2014) Don said:

I have a honeywell zone valve. I have 3 zones. 2 of the zones work fine. Problem is, when thermostat kicks on, the manual switch on valve does not move. It does call for heat, however there is none.

I manually moved the lever on the valve and still no heat or water through the pipe. When the thermostat is on, the lever is loose and the actuator is depressed but the lever is still in auto position. when thermostat is off and not calling for heat, the lever has resistance when I move it to manual, but does not allow for water to enter pipe or heat.

I manually moved the lever and depressed the button in the valve to call for heat but still no flow. Help????? Bad valve? Does whole thing need to get replaced. This sysptem was working fine for years.


Don I think when you are feeling the loose lever it's because the valve has opened on its own - normal operation;

But if the valve is broken internally indeed it could be in the "open" position (with respect to the zone motor and shaft) while the valve is remaining closed. I am guessing that the tech will remove the valve head and inspect for stripping on the valve shaft, then try moving it manually in the course of deciding on the extent of replacement needed.

Question: how to test for control valve stuck open

(Mar 21, 2014) Mark said:

I have a 5 zone system (3 of the zones work fine ) but the 2 lower zones are running continously. Could it be the control valves are stuck open - how would I test


Mark, turn down the thermostat for the zone to be tested, to a setting below room temperature, or disconnect it entirely. The zone valve should close. With a zone valve shut the heating water piping in the outlet side of the valve will cool down - something one can check by thermal measurement or by careful (avoid a burn) touch.

Question: trouble with Laars Endurance heater

(Apr 7, 2014) Ju said:

I have two LAARS Edunrance which were installed 6 years ago. Recently I turn down the temperature, the pipe is still warm. I mean I set the the temperature that is much lower than the room temperature, the heat is still on not sure what's going on. i feel i am wasting my money on the heat,

My second Edurance has the opposite problem , it has hot water but no matter how high the temperature i set , there is no heat or a little warm.

so i hope somebody can help, i am really sick of LAARS.

Question: relationship between zone valves and hot water tank?

(Apr 8, 2014) Carpenter said:

Would the zone control valves have been affected when a hot water tank was replaced?



It seems unlikely that replacing a hot water tank would affect heating zone controls with the following exceptions:

IF you were replacing an indirect-fired hot water tank that is heated by a separate heating boiler, the hot water tank acts as a separate heating zone on the heating system; if the tank replacement technician messed with controls or wiring on that heating zone then it may be operating differently or improperly.

IF when the water heater was replaced someone accidentally (or out of ignorance) bumped into or messed with a zone control (say trying to find the one that operated the indirect water heater) that might have led to an embarrassing snafu that someone may be reluctant to admit.

Reader follow-up:

Ch and hot water were on constantly and not responding to control panel and still on after set to 'off'. This followed hot water tank replacement. We had to employ different heating company who have sorted valves but my 86 year old mother is left with gas bill of over £400 as a result of this fault.

The original technician said he did not need to check everything worked ok as he was only replacing tank! Incidentally, the top of the tank had erupted like an open flower,it wasn't just leaking. Could this have been caused by valve malfunction to begin with and therefore should have been checked? The bill and gas charge together are £800 and I think we will just have to accept it! Thanks for your info.



What an aggravating snafu. It sounds as if there were multiple faults, and with the apology for sounding like a fussy old lady (I'm not, I'm a fussy old man), you all are darn lucky nobody got killed by a BLEVE explosion when that water tank ruptured. If you can send us some photos please do so, using the CONTACT link found at page bottom and I can comment further.

For a hot water tank (geyser) to burst open under over-pressure it is possible that it was not properly protected by a temperature & pressure relief valve.

It also sounds as if perhaps the original technician MIGHT have crossed up some control wires, not wired them correctly, been confused about which zone control was for hot water, or something like that.

And it also sounds as if possibly a temperature upper limit control was not connected or not working - which is mere speculation on my part since even at over temperature the TP relief valve should have been installed and should have opened.

There are other possible errors such as someone shutting off a water valve that left the system with no place to push expanding pressure.

It's not reasonable for us to diagnose too exactly what happened just based on a few text notes, but certainly it sounds as if improper installation, controls, safety devices, and possibly operation all were involved, and most critically: you want assurance that a qualified expert plumber has examined the system for proper installation, safety, and building code compliance.

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Question: adding under-floor heating to a hot water heating system

underfloor heating said:

do i need to install 2 zone valves in my heating system ,i am fitting a single room underfloor heating kit to my baxi combi boiler system



The requirement for additional zone valves hinges on whether or not there is a need to control heat to that area individually. If the single-room to which you are adding heat would not be adequately heated by the settings of the room thermostat that is presumably located elsewhere, you may want to add a zone valve and thermostat for the single room.

Reader follow-up:

so the kit can be plumbed into the main flow and return and use the existing thermostat



You did not describe your heating system so I don't know that your assumptions are correct. For example, radiant under-floor heat systems typically operate at a different temperature range and flow rate than hydronic heating that uses radiators or baseboards. So a hybrid system that uses a mix of heat types in different rooms may need separate controls of both flow and temperature. The temperature control is typically achieved by a recirculating mixing valve that prevents the floor from becoming too hot.


Reader follow-up

ok i understand i think lol can i fit a thermostat to the underfloor heating as well as the one on the main heating system the underfloor heating has its own pump thanks


Take a look at radiant floor heat designs - you'll probably see that a temperature control is also necessary for your system

Question: do I need to install zone valves for radiant heat flooring

(June 17, 2014) underfloor heating said:
do i need to install 2 zone valves in my heating system ,i am fitting a single room underfloor heating kit to my baxi combi boiler system



The requirement for additional zone valves hinges on whether or not there is a need to control heat to that area individually. If the single-room to which you are adding heat would not be adequately heated by the settings of the room thermostat that is presumably located elsewhere, you may want to add a zone valve and thermostat for the single room.

(June 17, 2014) Anonymous said:
so the kit can be plumbed into the main flow and return and use the existing thermostat



You did not describe your heating system so I don't know that your assumptions are correct. For example, radiant under-floor heat systems typically operate at a different temperature range and flow rate than hydronic heating that uses radiators or baseboards. So a hybrid system that uses a mix of heat types in different rooms may need separate controls of both flow and temperature. The temperature control is typically achieved by a recirculating mixing valve that prevents the floor from becoming too hot.


(June 17, 2014) Anonymous said:
ok i understand i think lol can i fit a thermostat to the underfloor heating as well as the one on the main heating system the underfloor heating has its own pump

and fit a zone valve with it



Take a look at radiant floor heat designs - you'll probably see that a temperature control is also necessary for your system unless your heating boiler is one of special design and model with those controls built-into the base unit. .

Question: can't turn off radiant heat in one room

June 30, 2014) Katie said:
If the zone valve is disconnected with it just run the hot water through the radiant heat? I ask this because our system won't turn off the radiant heat in our playroom. The valve was disconnected (flair valve) thanks!


Katie there are a couple of possibilities:

a zone valve may have been manually latched into the "OPEN" position

a zone valve may have failed and may be stuck in the open position

some zone valves may revert to "open" if their power source is interrupted.

Take a look at the valve to see if it includes a manual operating level;

Also be sure that the thermostat is not calling for heat - and that the thermostat wires are not shorted together (which would be the same as calling for heat).

See this diagnostic article

(June 30, 2014) kate said:
Dan the zone valve was disconnect at the boiler - would that mean that the boiler just sends heat to that area now? or should I put the valve in the closed position?
thanks so much for your help


Kate if the zone wiring is disconnected you'll want to manually put it in the Closed position - else you'll keep getting heat

Question: how to stop un-wanted heat in one zone

(July 11, 2014) Anonymous said:
I had an electrician change the hard wired boiler service changed to a plug and outlet arrangement so I can direct connect to a generator during power outages.

Normally the boiler is plugged into an outlet fed by household current. During power outages I unplug the boiler from the house outlet and plug it into am electrical cord connected to an outdoor generator.

My question is in regard to the thermostats. Am I just heating the boiler water when connected to the generator or does the boiler wiring also control the thermostats?

In essence, does the electrical power for the thermostats/circulator come from the same boiler electrical source (if I supply power to the boiler am I also supplying power to the thermostats/circulators) or do they have a separate power source?

(Sept 20, 2014) gordon said:
i have 3 zone s on gas boiler when zone 1 is on yhere is heat going zone 2 when it appears to be off


Gordon if this is a new problem I suspect a zone valve stuck in the open position or manually latched open.

Question: Taco zone valve feels warm

(Oct 12, 2014) Anonymous said:
when my basement zone valve is off and my first floor zone valve calls for heat i can feel warm water on the off side (pipe) in the basement zone valve. is this normal or should the pipe be cold? i have a taco zone valve.



Question: Smith boiler, wiring snafu hookup qwuestion

(Oct 13, 2014) Daq said:
I live in a very old house with a Smith furnace, 4 zones. The guy that installed it cut the wiring from the old furnace without marking the wiring indicating what went to what zone, he was in a hurry. Now we have rooms that are too hot and rooms with minimal heat. I am not sure who to call to fix such a mess and what is involved.

Question: new zone valve power head but won't open by motor control

(Oct 31, 2014) Anonymous said:
new powerhead will not open when called. all wiring correct and have 26 volts when thermastat calls for heat. i can manually turn open valve.


Anon: sounds like mis-wiring or a bad motor in the zone valve head.

Question: how to put radiatiors on a separate zone

(Nov 1, 2014) Gary said:
Is it possible to put two 3rd floor radiators on a separate zone with two pipe steam heating system in my old house?


Gary the practical way to achieve what you ask - more fine zone control over steam heat - is to replace the steam radiator's manual valve (right at each radiator) with a thermostatically operated valve that allows room or zone occupants to choose their own heat level.

As long as the boiler is making steam that'll work.

Running separate steam pipes to a 3rd floor and adding a thermostat is technically possible but expensive and iMO not feasible.

You can even more easily install thermostatically installed steam vents.



The article ZONE VALVES, HEATING - where you first posted this question, pertains to hot water or hydronic heasting, not steam heat.

Question: fixing a backwards-facing zone valve

(Nov 3, 2014) said:
Added another V8043 zone valve to existing radiant system but installed it opposite the designated flow direction. Will I be in trouble if I leave it as is.


Yes. I'd remove the valve and install it in the proper direction.

Question: how to find why zone is not heating

(Nov 4, 2014) Mike said:
A question, I have a zone that's not heating I hear no flow at all but the thermostat works, what I can't tell is I assume it would have a motorized valve but the motorized valves I see are for different areas how is it possible to pinpoint the area?


Mike you'll need to follow the heating piping to locate a zone valve - it it's not in the usual spot close to the boiler itself. Open the valve manually. If that works and if the thermostat wires are properly calling for the valve motor to open the valve and it does not, the motor head may need replacement. If the valve can't be opened manually - that is if it's stuck - it needs replacement.

Question: zone valve won't turn off

(Nov 5, 2014) Anonymous said:
my zone valve will turn on but I have to over ride it to shut it off



sounds like a sticking zone motor or valve - one of those probably needs to be replaced - BUT first check the type and model of zone valve you have installed. Some zone valves require voltage present on a "close" circuit to close the valve.

Question: intermittent zone valve cut-out

(Nov 12, 2014) Anonymous said:
2 year old boiler -My installer can not figure this out - It was a 2 fold problem - Pump - which is fix now. 3 out of 4 zone /thermostat work fine - One, works for 4-5 hours and then cuts out - If temp is set at 65, it gets to 63- Radiators are hot - And then shuts it self down for 12 hours -

Then the next day it starts to work for 3-4 hour and shuts down again Never stays on to get to the set temp. Zone valve has been replaced on all zones ,

Thermostats have been replaced. We can't seem to figure out why it works, good hot radiators and then shuts down, never getting to say 65. Radiators all have bee bleed of air. Live in Wisconsin, soon going to get crazy cold- We've been working on this for weeks. So frustrated.


check for an overheating zone motor that seizes when hot

Question: how far does a zone valve open

(Nov 14, 2014) Mike r said:
How far should a zone valve open ? Mine appears to only open slightly. Wondering if the lever should move all the way to the left.


Varies by model, but generally 180 degrees; the lever moves fully to the OPEN position.

Question: adding zones to an existing system

(Nov 17, 2014) Dave said:
I want to divide my central heating system in two so that I can heat rooms used during the day without heating the whole house.

I propose to do this by installing a 2 port motorised valve to interrupt the flow but am not sure whether to use an NC or NO valve for this purpose. It would be installed on the return pipe unfortunately not bear the boiler. Any advice would be appreciated.



You might find it easier to simply install a second zone valve on the second or divided heating zone loop.

Question: un-balanced heating in zones with zone valves

(Nov 17, 2014) Bill A said:
I have a Weil-McLain GV 4 boiler with an indirect water heater and three heating zones each with its own pump.

The third circuit ends up requiring heat much more often than the other two but there is significant circulation of hot water in the other two when their pumps are not running.

I would like to add Honeywell V8043E motorized valves to those two circuits to stop that flow. One of those circuits is presently controlled by a Honeywell R845A and the other by a Nix SP-81D. Both are connected to Honeywell two wire thermostats. I’m having difficulty figuring out exactly how to wire the new V8043E valves. Any guidance would be greatly appreciated.



Indeed there can be incompatability in wiring together different types/brands of zone valves on the *same* circuit. I don't know the Nix model you cite. When I got into this trouble I called my local heating supplier who kept an expert on staff (Dave Ferris, now retired) who could tell me - Oh yeah - just move that yellow wire over to T2.

Or check the wiring diagrams and instructions from the two manufacturers. Don't just use those pages to keep the soot off of your knees.

Question: Boss Therm zone valve problems B3P28

(Nov 26, 2014) Anonymous said:
I have an issue with my Boss Therm Motorised Valve, hopefully someone can help...

It's a b3p28, mid-position 3-way valve, and for a while now it hasn't been fully selecting the central heating option. The valve turns past the mid-position when the boiler is only calling for CH, but not far enough to engage, so the heating only comes on if both CH and water are selected at once. The water is working fine.

I've checked the motor, and it seems to be offering the correct resistance across its wires. The manual lever also appears to work, however it also doesn't seem to push far enough when fully open. ie. when I look at the cog underneath, this doesn't appear to turn far enough, even using the lever.

I have taken the motor off, and moved the mechanism by hand, and in doing this it does turn further around (ie. the valve seems to be fully opening and closing). The springs are tight, but it can be worked by hand.

Does this sound like a sticky/ damaged valve, or is it likely that by changing the mechanical workings alone I'll be able to fix it? And if so, does anyone know if this is possible with a Boss Therm B3P28?!

Thanks in advance for your help - any suggestions gratefully received!




No worries about the anonymous posting, though it'd have helped me to know the page where it was made. Sorry for the delay in replying - sometimes we get swamped with questions, especially when weather turns very cold or very hot.

I can only guess like you. But it sounds as if the valve body - mechanical parts - may be obstructed or damaged. Normally the manual open lever feels some resistance but will move smoothly and latch into place if the mechanical parts of the valve are working.

I'm not sure about the motor resistance test. A better test, but maybe not as easy to do, is to measure current draw when the motor is trying to run - to operate the valve. Higher than spec current (amps) draw would indicate that the motor is indicating mechanical binding and is under stress (or may even burn-up).

ELECTRIC MOTOR DIAGNOSTIC GUIDE was not aimed particularly at low voltage zone valve motors but still might be helpful.

Keep me posted and send along a sharp photo or two of the valve if you can - we may be able to comment further.

Question: bad end switch on zone valve

(Nov 28, 2014) Bill c said:
I have a three zone residential system with a slant fin Galaxy boiler and three Honeywell v8043E1012 normally closed valves. Had been having problems related to poor solder joints on controller relay but that seems behind me.

I think. Problem now is one control valve does not call for pump (single grundfoss ) to kick in. Works fine when either of the other two zones call. Zone valve motor works fine and zone is open.


Bill I suspect you've already guessed the most likely problem. Try making the end switch wire connection manually, off of the zone valve. If the pump runs then it's not the wiring or pump relay.

Question: zone valve manual latch loose

(Nov 28, 2014) Dominick said:
I have a 3 zone hot water residential boiler. I have a zone valve and/or actuator issue with one zone. When any of the other zones turns on, that zone pipe after the valve gets hot and that room temperature goes up 3-5 degrees and taht zone to that hotter room is off.

The manual latch is loose and does not function like the other 2 zone latches do.

I raise the thermostat temp 5 degrees above the actual temperature in that room and I hear the zone valve make a little noise and the circulator pump does not turn on. The valve is an Erie general close, end switch AG13A01A 24V, 50/60HZ 2 way valve. CV 3.5 with max system PSI at 300. 6.5 watts. Is it the valve, the motor, the actuator, all of the above? Thanks



It sounds as if the zone valve or motor has frozen and needs placement.

Question: bang on the zone valve body to get it to work?

(Dec 3, 2014) Bill said:
I have a gas fired hot water system with four zone valves, the one that is used for the main living area gets the most use. It is a one inch Honeywell zone valve. When heat is called for the valve opens, the circulator goes on and the boiler fires as needed, when the zone thermostat reaches temperature the zone valve stays open and the circulator keeps running with the boiler continuing fire as needed.

If I bang on the zone valve body hard enough the zone valve will close and the system will shut down till the next time heat is called for. I have no problems with the other zones. I'm thinking the valve and not the motor is bad, is there a rebuild kit or should a whole new valve be installed or could something else wrong?



If the zone valve closes when whacked it's mechanical parts are probably sticking. Too bad. It's less work to just replace the motor but I suspect the whole valve is needed.

Question: leaking aquastat frequent failures

(Dec 9, 2014) Don said:
I have White Rogers 1311-102 style aquastat. Both are leaking and need replacing. Every 2 to 3 years they need replacing because they start to leak. Both are on the return lines before entering the boiler.Our water here is very hard with a high concentration of calcium/lime.

Can I use a different Aquastat that would not not require changing them so often? And can this be done without harming the boiler?



Because the water in a hot water heating system is pretty much the same physical water all the time - it doesn't change unless the system is drained and re-filled or has a leak and keeps taking new water - I think the problem may be elsewhere. You could however discuss with your heating service company or heating supplier the use of a chemical treatment or additive to put into your boiler water.

I would look more closely at exactly where the leaks are occurring. For example if an aquastat probe sensing well was improperly installed or threads were cut or damaged the leaks could be recurring independently of the control itself.

Conversely, you should consider installing a water softener to protect the rest of the building water supply system.

Question: zone valve clicking

(Dec 9, 2014) Anonymous said:
My zone valve clicks when call for heat motor moves and zone is open what can it be


Anon I'm not sure I understand the question correctly. On a call for heat the zone valve motor should open the valve and when it's fully open an end-switch in the valve turns on the circulator. If your valve makes noises and does not open I suspect the valve is jammed or the motor is shot.

Question: zone valve stuck

(Dec 20, 2014) Rick said:
I have a bad zone valve that is stuck somewhere between open and closed. I get warmth in the pipe on the upstream side of the valve, but when the thermostat calls for heat the circulator and boiler never kick on. I get some heat in that zone when other zones are running. Can I somehow override the end switch in the valve so I get heat in the zone?


The end switch on a zone valve is basically connecting two wires that turn on the zone circulator relay or pump switch.

Question: water hammer noises after zone valves changed

(Jan 1, 2015) Johnson said:
Replaced boiler and zone valves(3), then water hammer started. The installer temporarily stopped it by adding a small expiation tank and increasing water pressure. Hammering returned on one zone, but does not occur on every closing of zone valve.

I cannot totally prove this, but it seems if another zone is open at the time this one closes there is no hammer. By the way the service company, with several techs, are stumped. Any clue?



Water hammer occurs due to a sudden closing of an open water supply valve. It might also occur on a hot water heating system through a similar phenomenon.


Question: how to balance heat between zones

(Jan 10, 2015) billy said:
I have 2 zones, 1 to living room 1 to bedroom this is a ranch style home with manual zone adjusters only, my question is,how do I adjust the flow to get less flow to bedrooms which I like to keep a little cooler the style I have is the type that requires a screwdriver and I don't know if I turn only vertical/horizontal, or turn all the way in or out?



It would help if you'd send me some sharp photos of your one valves and their controls - use the email found at our CONTACT link at page top or bottom.

Typically you close a valve by turning it clockwise to reduce flow or to stop it entirely.

For some simple flow balancing valves operated by a screwdriver turning the screwdriver slot to right angles to the piping will close the valve.

Question: where to buy a flow balancing valve for heating zones

(Jan 11, 2015) Jeff said:
Where can I buy the "hot water heating zone flow balancing valve"


Jeff I'm not certain what kind of valve you're looking for but if you are definitely talking about heating zone flow control, stop by your local plumbing and heating supplier.

Question: heat stays on when turned off if other zones call for heat

17 Jan 2015 Anonymous said:
i have baseboard heating with 3 zones. 1 for the basement, 1 for the bedrooms and the last for the living areas. when we turn on the thermostat for the basement the baseboard heat turns on in the basement and in the bedroom zone.

I can turn the thermostat off in the bedroom area but the heat will still stay on if the basement is getting heat. last year all 3 zones worked correctly. Any ideas?


If you turn off heat at a thermostat and heat stays on in that zone when other heating zone thermostats are calling for heat I suspect a wiring error or shorted thermostat wires, or a zone valve that is mechaniacally stuck in the open position.

Question: unwanted heat at zones

Valerie said:
We have a three-zone boiler system in our house. One zone controls the living room, dining room, and kitchen. One zone controls three bedrooms. And the last zone controls the family room, laundry room, garage, and two storage rooms.

When the zone for the 3 bedrooms calls for heat, the zone in the living room, dining room, and kitchen seems to also be receiving/circulating hot water and the registers get warm, but not hot enough to increase the temperature in that zone. Is this normal? We are new to this type of heat.



I was about to answer when I got confused by your word "registers get warm" - I think of registers as delivering warm air from a heating furnace.

If your heat is from a hot water boiler heating hot water baseboards or radiators,
if we can assume that your thermostats are not calling for heat
and if we can assume that you're not just feeling left-over warm baseboards or radiators after the end of a heating cyle
that is
if you mean that the zones not calling for heat continue to have baseboards or radiators well above room temperature for hours after there has been no call for heat
check for zone valves that are not closing fully, or check valves at the boiler that are not working.

Let us know what your heating service tech says.


Question: How do I know how many zones do I have?

(Jan 24, 2015) Chris eden said:
How do I know how many zones do I have if I see 3 cold & 3 hoot lines in my furnace room, 6 lines total from the floor



Normally each heating zone has its own thermostat. Count thermostats.

Question: boiler never turns on to bring heat although the zone valve opens

(Feb 1, 2015) Mark said:
The zone valve for my main floor opens when the thermostat calls for heat, I can easily slide the lever from auto to manual with no resistance showing the valve is open, but the boiler never comes on to bring heat to the baseboard radiators.

It seems that the thermostat sends a signal (voltage) to the valve, the valve opens but no signal is sent to the boiler. Is this a problem with the valve? The other two zones respond the same way except that the heat does come on.


Mark the zone valve has an "end switch" that should turn the boiler on when the zone valve is fully open. Of course whether or not the boiler actually fires on a call for heat from that switch also depends on the boiler temperature and what the aquastat is telling the boiler to do.

You can test that the zone valve calls for the boiler to run at its end switch by jumping those two wires. The circulator should run at that point and if the boiler is not hot, the burner will also turn on.

Reader follow-up: (Feb 3, 2015) Mark said:

Thanks, DanJoeFriedman, I have a Honeywell V8043E1012 normally closed motorized valve, the wiring diagram inside the cover shoes the end switch to be two red wires.

Fortunately I have a fireplace insert on the main floor so I can wait until Friday when I am not working a full day to try jumping the wires together and have time to get a replacement if necessary.

Question: burning fume odors when Taco brand zone valve opens

7 Feb 2015 Sharon said:
I have a gas boiler with two zones. When the upstairs zone valve (TACO brand) opens I smell fumes as if from burning plastic. I had it replaced a couple months ago and it stopped, but now the new one is doing the same thing.

The repair man who replaced it seemed to think I was imagining it, but replaced it anyway and the problem did resolve for a time. Does anyone have any idea what could be causing this?


Sharon since you're talking about hot water heat, I am guessing the smell you described is from an electrical or control component that is overheating. Watch out for fire hazards.

I don't assume the repair person is right that you're imagining odors - unless you suffer from some neurological illness - but people's sense of smell does vary widely. See if you can get corroboratin and see if you can sniff your way to pinpoint the odor source.

Reader follow-up:

Thank you! I am sure the odor source is the zone valve. I smell it immediately when the upstairs thermostat kicks in and the valve opens. It is not continuous, and as I said, it resolved for a time when the valve was replaced.

Sharon said:
Does anyone have any input about this problem? Does a zone valve have any components that could present a fire hazard?


Zone valves themselves operate on a low voltage wiring system (24VAC) and draw low current - unlikely to be a fire hazard. The end-switch on the zone valve is switching a 120V circulator motor (typically) or another 120V component in which, if there were an electrical short, there could be a burn-up of electrical components if the appropriate circuit breaker or fuse were not doing its job.

Check wiring and nearby equipment to see if the zone valve is overheating.

Check for boiler fluid leaks - if there is antifreeze in the boiler that might also contribute to an odor.

Question: one zone not working, doesn't turnon the circulator

9 Feb 2015 Mike said:
My dual zone system is not working in 1 zone. Thermostat has been changed but still not turning on the circulator when calling for heat. Upstairs is working correctly and turning on the circulator. 1 circulator runs both. Any ideas?

9 Feb 2015 Mark said:
To anyone having similar problem, where the thermostat calls, the zone valve opens but the boiler does not come on, it could be the motor.

The end switch is an actual switch. I removed the motor then the switch and pushed the button on the switch and the boiler came on. I disconnected the motor and replaced with a new one, this is one screw and two wires, all is working now.


Good comment Mark; indeed we often refer to the "end switch" on the zone valve as one of the test points; if the end switch is not working the zone valve may open or close in response to the thermostat but it won't turn the circulator on or off.

Question: how does the zone valve motor avoid burning itself out?

12 Feb 2015 Chuck said:
I just replaced the motor on my Honeywell V8043 zone valve and is working fine. I was intrigued how this hearty little motor worked, so I removed the cover on the old motor. The simplicity and durability amazes me not to mention the significant gear reduction. Can anyone tell me if there is some sort of slip clutch or other means in the head unit that that allows this little motor to rotate without burning itself out while it continues to hold the valve closed and makes the endswitch until the thermostat opens?


Chuck, (speaking beyond the edge of my expertise)

Typically the Honeywell V8043 series of zone valves are a "normally closed" valve that is opened by its motor that turns the valve against a spring. When the "open" signal stops the valve is closed by an internal spring.

Zone valves with a manual operating lever are intended to be able to be opened to allow heating water to circulate by "gravity" or convection during a power outage - of course since on most systems the burner will also be off during a power outage the duration of this benefit is limited.

But it seems to me that the manual design and the spring-closure design mean that the 24VAC motor simply is held in the open position without burn-up on a call for heat, without a slip clutch and often lasting for decades.

In actual operation the class F (temprature tolerance) synchronous motor of the zone valve is drawing at most about 7.7 VA

Question: my zone valve motors are fine but the valve shaft keeps seizing up

13 Feb 2015 Tim said:

I have a nine zone hot water baseboard system armed with Honeywell controllers( normally closed).

I have replaced faulty controllers over the years but that gets costly. The fault seems to always be sticky valves that stop closing. The motors are fine but the shaft seizes up to the point that the return springs can't close the valve completely, causing constant hot water circulation. Has anyone had any luck reconditioning the valve unit itself?



The newer Honeywell zone valves use a rotating rubber ball valve that presents a new surface to the closing orifice each time the valve rotates, expecting to offer longer service life. I wonder if you've been replacing just the zone valve controller head but putting new heads on an older, sticky valve body. Have you tried installing the new valve body type?

Question: have hot water but no heat

(Nov 16, 2015) Dave said:
Oil boiler / baseboard heat.

1. Have hot water but no heat
2. Thermostat wires secured, batteries replaced, switched on forced air switch
3. Boiler turns on to replace lost hot water.
4. No breakers are tripped.
5. Bled the line, constant stream of clean fuel. Got fueled same day.
6. Emergency shut-off switch not engaged.
7. Emergency starter (we have a little red button) is not tripped.
8. Definitely sure nothing is coming from the baseboard heaters.



when the thermostat calls for heat, the circulator should turn on - which you can confirm by listening or feeling the exterior of the circulator pump;

and if the boiler is cold the burner will come on;

if the boiler is hot the burner may not come on until later

But in either case the pipes to and from the circulator pump should be hot.

If the circulator is running and the pipes are hot look for an air bound heating system or a zone valve that is not opening

This sequence is where we start

Nov 16, 2015) Dave said:
-Circulator did turn on
-The upstairs heat works (confirmed)
-1 of 3 pipes coming from the circulator is hot

Found the problem, it was a zone valve not working and we flipped the switch. It needs to be replaced.

Thank you very much for the help, I really appreciate it!


Good going, Dave.

With many zone valves you can hook the valve in the manual-OPEN position so you'll continue to have heat in that zone while waiting for repair. If the failure is in the zone motor that may be replaceable without having to solder in a whole new zone valve assembly. But if the problem is the valve itself jamming I'd go ahead and install a whole new unit.

Question: banging from zone piping when thermostat stops calling for heat

(Nov 22, 2015) Bob said:
The house warns fine and there is no air in lines. Zones valves open fine to reach temp but when the temperature on the thermostat is turn down it bangs. What is causing this? It does it on all zones.



You are describing a water hammer problem that usually is traced to a high-speed closing zone valve combined with the velocity of the circulator water. The solution may be to install an anti water hammer device, to install a slow closing the valve, or to review the circulator speed if you have a variable speed circulator pump.

Question: remove or replace a zone valve

(Nov 13, 2015) Anonymous said:
how to remove a zone valve

(Nov 23, 2015) Replace motor or whole valve? said:
I sometimes have come home to find my house is really hot because the zone valve is stuck in the on position. I tap it with a wrench and it then clicks off. Lately this seems to be happening more often. Do you think I need to replace the whole valve or can I get away with just replacing the motor assy.

(Nov 24, 2015) Garrett said:
Is there a core return on zone valves



Try removing the valve head to see if the valve assembly itself moves freely. If it does replace the control head. If not replace the whole assembly.


If you are asking if you are supposed to return the non-functioning zone valve core to your dealer, no.

If you are asking if the zone valve is self-closing, that feature is provided in some valves that are of the Normally-Closed variety; look for the controls and the normally-open vs. normally-closed specification on the zone valve model.

Question: grating noises in zone piping

(Nov 30, 2015) sam mcclenahan said:
I have older Honeywell zone control valves on my Buderus home hot water heating system. The opening and closing of the valves reverberates through the copper pipes and makes a surprising amount of loud grating types of noises throughout the house. Is there a way of isolating the valve vibration from the pipes.



I suspect the problem is a form of water hammer (Search for WATER HAMMER for details) that is due to rapid-closing zone valves and the velocity of water in the heating piping. If your circulator is a variable speed unit (probably not) try a lower speed setting. Otherwise an option is to change out the zone valves for slow-closing models. Before doing that however I'd ask your heating service tech if installing anti water hammer devices on the zone piping might work. I don't think that vibration isolation pipe mounts will do the job.

Question: uneven heat among different heating zones

(Apr 10, 2016) Lisa said:
we have zones in our home. We have discovered that in one zone the room where the thermostat is located seems to be the accurate temperature but the adjacent room is much much warmer. Any thoughts on what the problem might be


Sure, Lisa. It would not be a surprise to find different rooms at different temperatures while they are nevertheless on the same heating zone. Some causes include:

1. open or closed baseboard top vents
2. dirty vs clean finned copper tubing
3. carpets blocking bottom air inlet under baseboards
4. if radiators are in use, closed vs open radiator valves or even partial air blockage of radiators (or baseboards)
5. different rates of heat loss in different rooms: windows that are open or leaky, doors that are open vs shut vs under-cut vs tightly-closing
6. and very basically: rooms that receive the heating water first in the piping loop get the hottest water.

Question: zone valve too hot to touch

(May 10, 2016) Jim said:
I just noticed that a zone valve located in the baseboard is always hot -almost too hot to touch. No matter if the heat is on or not, and there is a slight burning smell coming from the valve as well. Is this normal?


If the heating pipes to and from the valve are cool and the valve body is hot, that Sounds like an overheating or burning-up or seized zone valve motor.

Try removing all wire connections from the valve.

Question: Dunkirk HE boiler, shut off zones in summer?

(May 29, 2016) sue said:
i have an He boiler (dunkirk) that the hot water heater piggy backs off of, a total of 3 zones, two to radiators thru out the house one for the hot water tank, was wondering if i could shut off the radiator zones during the summer since the radiators become ambiently hot when boiler is called to fill hot water tank, thanks for your expertise



You could, but that doesn 't sound like the right fix. THere is probably a zone valve that sticks open or a check valve that sticks open - that needs to be repaired.


Continue reading at ZONE VALVES, HEATING or select a topic from closely-related articles below, or see our complete INDEX to RELATED ARTICLES below.

Or see ZONE VALVE DIAGNOSTIC FAQs - more-recent zone valve troubleshooting questions & answers

Or see these

Zone Control Articles

Or see ELECTRIC MOTOR DIAGNOSTIC GUIDE to test zone valve motors themselves

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