Boiler Boiler Aquastat Diagnostic FAQs
Building Inspection, Diagnosis & Repair Info

A multi function combination aquastat control on a heating boiler, Resideo/Honeywell L8124 A,C (C) Daniel Friedman at InspectApedia.comBoiler Aquastat Diagnostic FAQs

Index to Aquastat troubleshooting & repair Q&A

Diagnostic questions for aquastat controls on heating equipment:

These questions & answers help you to understand how to set an aquastat's HI, LO, DIFF dials & how to troubleshoot & repair this heating boiler control.

This article series explains how aquastats work and what the different aquastat controls are, what they do, and how they are set. We define the HI LO and DIFF controls on heating boiler aquastats and explains what they do and how they work.

We explain the location and use of the heating boiler reset button found on aquastats.

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Aquastat Diagnosis Q&A

Aquastat hi limit controlQuestions and answers about aquastats posted here or at AQUASTAT CONTROLS or at AQUASTAT TROUBLESHOOTING.

Be sure to see the aquastat diagnosis and repair advice in either of those two articles.

This page includes our our index to all boiler aquastat questions and answers.

Article Index

...

Aquastat Does Not Turn ON the Circulator Pump FAQs

Tip: See our complete diagnosis and repair procedure at CIRCULATOR PUMP WON'T START - topic home,

and also see these additional CIRCULATOR PUMP WON'T START FAQs 

Aquastat won't turn on the circulator - what's a temporary bypass fix?

I have a weil mcclain oil fired boiler with a disabled domestic hot water coil, bolier is firing goes up to 180 as set. but the circulator is not coming on.

I hot wired circulator and circulator runs fine. I have 120 at L1 L2.

I have assorted voltage at C1 C2. C1 C2 Has been as low as 7 sometimes goes around 40 went up to 120 once for few seconds so I have disconnect circulator not to burn it out.

Thermostate has like 3 volts . transformer has 21 volts has been up to 27 volts( could just be my volt meter).

Is 11 dgrees out getting heat by convection or pluging circulator in for 20 min.

I think is aquastat. should I bypass the low side( if so how) to further diagnosis aquasts On 2018-01-01 by edward

Reply by (mod) -

That sounds like a bad circulator relay or a bad aquastat. If the circulator runs I'd be inclined, in an emergency, to wire it to run continuously, disconnecting it from the aquastat until that can be diagnosed and repaired.

Then the thermostat will simply turn the burner on when the boiler temperature is low.

 

What do I check first if the hot water heating circulator won't come on?

My boiler won't circulate the hot water. I have changed the pump and the aqua stat has a broken pin where the switch would click.

Does that make a difference? The switch is clicking/pulling in but hot water won't circulate. Any suggestion what could be wrong. (Apr 21, 2014) Chanthy

Reply:

Chanthy

First check that the thermostat is calling for heat and the thermostat wires are pulling in the circulator relay.

In addition to checking and repairing the aquastat if its relay is not pulling in to turn on the circulator, check that any zone valves or manual control valves are open (if present).

See our detailed diagnosis and repair procedure

at CIRCULATOR PUMP WON'T START 

 

My thermostat wires got crossed and now my heating circulator pumps won't run

Thermostat wires got crossed a couple of times before I could get them apart. furnace fired up a couple of times. fixed wires ,furnace runs fine but now wont circulate.it is a r8182 Honeywell . On 2017-12-18 by randy

by (mod) - Shorting thermostat wires might burn up a low voltage transformer,

Randy

Shorting thermostat wires might burn up a low voltage transformer, though it's not common.

The thermostat is basically an on-off switch, so you'd think that shorting the two TT wires together would be exactly the same as calling for heat continuously.

You might want to look at our step by step THERMOSTAT DIAGNOSTIC GUIDE

Then on a call for heat - setting the TT all the way up, see if the circulator is receiving voltage (Watch out you can be shocked and killed - if you don't know how to work on wiring safely get help from an electrician)

The Honeywell control you cite is, of course not the thermostat but an aquastat - described at AQUASTAT R8182-SERIES CONTROL

 

Honeywell Triple Aquastat 8158A won't turn on the circulator pump

I am running a Honeywell triple aquastat L8151a with

(1) circulator pump and

(3) zones. My thermostat is calling for heat, and the zone valve is open.

The circ pump doesn't come on line and therefore the boiler does not go online either.

I have replaced the pump and have been able to make it run by forcing the circ pump relay closed.

Of course as the cooler water enters the boiler, the boiler lights off. I have checked all Hi and Low and Diff settings.

All look within the parameters described above. Is it safe to assume that the aquastat needs to be replaced? Is this aquastat suitable for this kind of (3) zone, (1) circ pump operation? This boiler does include the domestic hot water service. (Feb 26, 2013) Joe B

Reply: if forcing the circulator relay closed turns on the circulator pump ...

Tom,

Since manually pushing the circulator relay on the aquastat closed turns on the circulator, we know your aquastat and your circulator pump both have electrical power.

Check the thermostat & its wiring:

Before replacing the aquastat I would double check that the problem doesn't start at the thermostat; unhook the thermostat wires at the aquastat end and just jumper the two T T terminals. That's the same as the thermostat calling for heat. If that turns on the circulator then we know the problem is the thermostat or its wiring.

The aquastats used on a heating boiler, because they have more jobs to do, are the devices shown at AQUASTAT CONTROLS - home

And domestic hot water for washing and bathing, if made in a dedicated water heater, perhaps in your case a hot water tank heated by a gas burner, will also have a limit control, but a simpler one - search InspectApedia for Water Heaters to see those controls.

In any case, no aquastat holds off on delivering water - these are temperature controls that turn a burner (oil or gas) on and off.

For your second question: most residential hot water supply systems (we're not talking about heating water in baseboards, we're talking about hot water at the sink) are one-way systems: cold water input pressure at the water heater pushes hot water out of the water heater on to the building fixtures when someone opens a hot water valve - say at a sink.

There are hot water circulating systems, used e.g. in apartments and other large buildings, that keep the domestic hot water supply circulating through a loop of piping all the time so that there are not long waits for hot water at the fixture; those systems include an additional circulator pump and heater control.

From just your question I can't say what you've got installed. You're welcome to use our CONTACT link to send photos if you like.

If the problem isn't the thermostat, then see our detailed diagnosis and repair procedure

at CIRCULATOR PUMP WON'T START 

 

On a call for heat the boiler runs but the circulator doesn't

I have a home boiler used for radiator heat only.

I have a Honeywell aquastat controller for the boiler(I am not at home so I cant look at any model numbers or brands) which is about 3 yrs old and the boiler and pump about 7 years old

. My boiler is currently functioning like this; the thermostat is on and calling for heat, the boiler turns on and starts to heat and the electronic flue opens.

The boiler runs for 30 sec or a min. With no circulation pump turn on and the boiler shuts down and the flue closes.

Last time I had a problem with the pump it was just loose wires under the protective cap where the aquastat wires tied into the pump wires but I checked the wires and they are tight. I think the aquatstat is not telling the pump to turn on (I think the pump is spinning free but I will have to double check as there is not much to grip or spin to be able to check).

I tried turning on and offthe main power switch to see if it would reset but no dice. I have my heating guy coming over later when I get home. Any suggestions? (Jan 26, 2015) Joe Dlouhy

Reply:

Joe if the circulator does not run the boiler should still keep firing until it has reached its upper limit as set on the aquastat. Start by confirming that.

Then feel pipes at the outlet and inlet of the circulator for heat.

If the circulator isn't running on a call for heat there's a bad circulator relay, control, or circulator pump.

If the circluator is running but the pipes never get hot the circulator impeller could be bad but the most-likely problem is air in the heating pipes.

See the diagnosis and repair starting at

AIR-BOUND HEATING SYSTEMS - home

...

Aquastat Settings if Boiler Does NOT also Make Domestic Hot Water

Tip: see detailed instructions at AQUASTAT LO & DIFF DISABLED

Peerless WB-3 boiler with a Honeywell L4081b 1047 aquastat. I don't need the boiler for domestic hot water

I have a tankless Peerless WB-3 boiler with a Honeywell L4081b 1047 aquastat. I don't need the boiler for domestic hot water because I have a separate electric water tank, so I only use the boiler for heat. Right now the aquastat is set to H 180 L 160 Diff 10. Should I change the settings? Can I disable the aquastat and how do I do it on that specific model? (Oct 20, 2014) Ray

Reply:

You don't have to do anything, Ray, but as we noted earlier in this FAQs series, if you want the boiler to stop maintaining temperature when there is no call for heat (which it will do for the tankless coil), then you want to read

AQUASTAT LO & DIFF DISABLED

...

Aquastat Failure Causes & Symptoms FAQs

What are the symptoms / causes of a bad aquastat

What happens to a l4081b aqua stat when it gos bad? (Nov 21, 2014) Don

Reply:

Don there are several failure modes in aquastats:

- a failed relay no longer switches on or off as it should

- circuit board components can burn-up

- a temperature sensor may fail

- wiring connections to the device may be loose or broken or shorted

 

What do do if our White Rogers Aquastat trips circuit breaker

My White Rogers aqua stat reaches my set temp and trips the circuit breaker (Oct 4, 2015) Ray Pierce

Reply:

Check for a short circuit on the oil burner, circulator, or zone valve circuits or a loose wire or a failing oil burner motor.

 

Boiler runs when I tap on the aquastat relay housing - or it used-to. What do I test?

Furnace does not turn on. Initially I would tap aquastat relay housing housing and furnace would come on. Then nothing. Manually opened switch in aquastst and furnace works fine, shutting off and turning on in cycles when hot limit is reached. Once I release switch the furnace shuts off.

How can I test if switch in aquastat is faulty or if something like maybe cad cekll relay is not sending proper signal? (Dec 20, 2015) Skip

Reply: Bad Cad Cell Sensor vs Signs of a loose electrical connection or failing relay or bad sensor probe on an aquastat

Skip:

If the cad cell is not sensing flame it will shut the burner off about 15-25 seconds after the burner has begun to spin but no flame is confirmed.

If there is a good flame then the cad cell may be bad - usually the tech swaps in another one. Sometimes I try wiping soot off of the cell face. IF the face is sooty the burner is running dirty and needs service or repair.

If the cad cell is replaced I suspect a loose electrical connection or a failed temperature sensor probe on the aquastat control.

Skip said: forcing the aquastat relay switch makes the boiler run

Thanks. Been lucky with warm weather here in northeast, turn unit on only for hot water.

I prop open aquastat switch and it runs fine, flame and everything seems to work, cycles on and off as normal.

However, I am certain "propping open" switch not a safe thing to do all winter.

I close system down and shut off electricity for the night after heating up home.

Will look for soot on cell face, but does not the fact that I get a strong flame and the system works fine with the aquastat switch propped open suggest either the aquastat or cad relay is the problem?

Thanks in advance for your advice.

Reply:

Watch out: Propping open an aquastat switch is dangerous. You are defeating a safety control: that can result in fire, explosion, injury or death.

If the flame looks good that's encouraging, though the smoke level could still be too high, or there could be a draft or unsafe chimney problem.

In my opinion the system and its chimney, venting, combustion air, oil burner and control all need service, cleaning, and perhaps repair.

Skip said:

Furnace serviced 11 months ago, I specifically asked to ensure chimney was working properly regarding air flow and draft, was told his test indicated all OK.

He did mention potential problem with cad relay, for future consideration, but furnace worked all last winter with no problems, and we had a brutal winter last year. I am disabled and on a fixed income and cannot afford to have a service call costing hundreds of dollars hence looking to see if I can fix it myself.

Changing out aquastat or cad relay does not seem to require any complicated calibrations or anything, look more like disconnecting and reconnecting wires and properly inserting aquastat probe.

I'm trying to narrow down which may have failed before spending the money on a new one. Estimate last year to replace cad relay was around $600, cost of unit seems to be a fraction of that, hence my effort to do it myself.

Would not try if I was not confident in my abilities, don't want to burn down my house. Checked chimney outside, no smoke issues, a sign I read might indicate other issues. If need be, will change aquastat and cad relay, but making an effort to see if I can narrow down problem before spending money.

Also, have carbon monoxide detectors and smoke detectors to alert if CO2 or smoke condition exist, fire extinguishers all over the place. These are day to day precautions, not a counter measure because of concerns over this situation. Not a total dummy, just sometimes.

Reply:

From your notes it sounds as if a simple fix to try - very inepxensive, is to just swap in a new cad cell eye. It's a two-pin plug-in device in the burner tube.

Skip said:
will try - Thanks! Happy New Year to you and yours!

 

Why would my 1 year old aquastat need replacement?

Hi Just wondering if I'm about to get ripped off or should i tell this person not to do the work.

I have a 1800 sq foot 2 story house and the farthest bedroom on first floor (2 outside walls) away from the furnace in the basement (consistently freezing cold outside) has been much colder than the rest of the house (tenants keep heat at 75 and this room hovers around 64-68) It's a gas furnace -

He told me its a Peerless Boiler and he is factory authorized dealer and the date on the boiler is May 2012. I have hot water radiator heat

This new heating guy says the one year old Aquastat Control needs to be replaced - that it is a part failure unrelated to the workmanship of the previous contractor who did the work last year (i switched from Oil to Gas).

That if he repalces the control that there is a 70% chance that this will solve the coldness problem in the back bedroom will get warm.

If the whole rest of the house has been warm without any problem - is this really the problem, wouldn't the rest of the house be cold too? He wants to charge me $535 for the control 4 hours of labor at $65 an hour.

Now - its 2 days later, he did the work because my tenant was yelling and the property manager approved it.

The room is still cold and now the contractor is saying the baseboard heaters were installed wrong and need to be 'reworked' for $450. He said that they are upside down and this is why the room isn't warm (same original contractor who put in the new furnace put in these baseboards in last year).

I called the original contractor (wish i brought him over this time to begin with) but I'm working with a property manager now).

He says that what this guy is saying is not true - that they were put in correctly. It was me who decided to use a 4' shorter length on one of the walls and this could be the issue, but why then did this new guy have to replace the control for $795?

Do they Honeywell Aquastat Controls really cost $535 or is that way high? Thank you for any help or advice anyone can provide. -Paula (Feb 13, 2014) Paula

Reply:

Paula we just replied to this question over at our Heating Baseboards page - please search InspectApedia for

Baseboard Heat

to see your question and our reply along with a photo of baseboard that is "right side up"

I can't understand how an aquastat would make one room on a floor cold but not the others, though indeed if a heating zone is quite long or piping runs through a cold area, the ending baseboards in that zone could be cooler than we'd like. But that problem would not be caused by the aquastat in a way that I can see. Details are in the article I cite.

...

Aquastat Won't Turn on the Boiler FAQs

Oil boiler with a Honeywell r8182f aquastat, not sure if the relay switch is bad, but boiler won't fire up.

I have an oil fired boiler, it seems that I am having problems with it starting, thermostat seems ok, power to the aquastat, etc,

but what I am experiencing is when I turn the power on to the unit, all I get is a clicking sound inside the aquastat, take the cover off and look,

I see there is a reset button and next to it a single relay switch, and that is where the clicking sound is happening, turn power on and the switch clicks but will not fire up the boiler, it has a honeywell r8182f aquastat, not sure if the relay switch is bad, but it won't fire up. (Feb 21, 2015) Tom said:

Reply:

From your note it sounds like a bad relay. You tried the reset button ONCE, right?
Start diagnosis at

HEAT WON'T TURN ON

Reader follow-up

Tom

relay is not tripped, when I turn the thermostat to call for heat the relay switch pulls in and makes a clicking sound but the boiler won't fire, does the same if I leave the thermostat up and turn on the power switch to the boiler, its like the switch pulls in and clicks but not firing up the boiler, bad aquastat or maybe the transformer on the boiler itself, any help would be appreciated.

Reply:

If the burner is NOT off on RESET and the electric motor doesn't start up on the burner when the relay pulls in, I'd look for a bad relay or bad wiring connections. Double check that the boiler is not off on safety.

Tom

well the relay pulls in like I think its supposed to, maybe I'm wrong, but the motor does not turn and it does not fire, so with a call for heat the relay shouldn't pull in or click in, is this correct.

Reply:

If the burner relay on the aquastat does not stay pulled in it may be a bad relay. Check for voltage at the motor terminals.

Tom

no, it seems to stay in as long as the thermostat calls for heat, it will infact pull in and out with the thermostat being turned up or down simulating a call or cancel for heat, don't think i have voltmeter that is working properly, do have a continuity tester, but probably not the right tester for the job.

Tom

ok, an update, when I turn the thermostat to call for heat, and leave it on for a couple of minutes, the reset button does pop, not sure if this helps.

Reply:

So the burner is going off on reset. This will happen any time the cad cell relay never sees flame after about 20 seconds. If the motor never even tries to run and if you have voltage at the motor then

  • check for a popped thermal overload button on the motor (not all burner motors have this switch).
  • check for a seized motor shaft
  • check for a seized blower fan shaft or a broken or seized coupling
  • check for a seized fuel unit (oil pump)

If you're not seeing voltage at the motor then there is a disconnected wire or a failed aquastat.

In sum:

The reset switch on the cad cell relay or in an aquastat will trip in a short time, perhaps 30 seconds after the aquastqt tries to start the oil burner if no flame is sensed.m

If at startup the motor does not run at all, a thermal protective relay may have tripped on or in the motor, or the motor or any of the devices it tries to rotate may be seized.

Check for voltage to the burner at the attempted start.

Tom said:

picking up a volt meter on my home tomorrow, will let you know what I find, thanks for all your help so far..

 

PEI (Canada) Aquastast is shutting off heat, have to reset

The oil fired hot water heater, installed 2011 and serviced annually, in a rental property in distant PEI is giving me grief. In winters, the heater shuts off, and I have to call for service.

Technicians have not been able to find the root cause, but often the issue is resolved by pressing the reset button.

It is 60 gallon unit, servicing the six 1 bedroom apartments with regular tubs. What could be the likely cause - faulty aquastat?

Does the aquastat have any electrical components that is impacted by moisture or electrical surge?

I need some direction to be able to ask the right questions. Thank you. 1 March 2015 Raj Mathews

Reply: check for an oil burner safety control turning the oil burner off - not the aquastst's fault

Raj

Typically if the heater is shutting off on reset it's because of a combustion or fuel or ignition problem at the burner.

I don't assume it's the aquastat but it might also be a loose wire at the aquastat.

Ask the heating techs to look for signs of a combustion or ignition or fuel problem that's tripping the safety switch, such as sooting, smells, etc.

Watch out: do NOT keep pressing that reset button to re-start your oil burner if it won't keep running for 5-10 minutes. The risk is a dangerous puffback explosion.

For details you might want to read all of the causes of an oil burner tripping off on "reset" or off on "safety"

found at OIL BURNER STARTS but then STOPS and WON'T RE-START - reset button popped up?

Or see our complete diagnostic steps at OIL BURNER WONT RUN 

 

Honeywell L4006E aquastat troubleshooting: Aquastat reset button tripped & we have no heat

Hi. Your site is fantastic.

I believe I looked everywhere on your site and have not been able to find an answer.

I have a gas hydronic heating boiler that is used for baseboard heating, as well as for our hot water. The hearing is for one zone only, and there is a circulator as necessary.

There is a combination aquastat that controls the high and low limits. In addition, there's a manual reset high limit aquastat (Honeywell L4006e) set for 200 degrees).

Recently, when there was no heating going to the baseboard, we noticed that the manual reset button was tripped.

We reset it and it worked ok for a few hours. Each time we reset it, it seems to work ok, but only for a short period. I believe the boiler shuts off on high limit as set in the combination aquastat, BUT the temperature still rises substantially and therefore power gets tripped by the high limit manual reset aquastat (set for around 205 degrees).

I figured I can adjust the combination aquastat settings so that it would not trip.

I set the low limit at 155, the high at about 185, the differential at 15, and the manual reset at 205. This should have helped (in my opinion) but it still tripped.

One final point, there are three other identical boilers in the room next to ours, and the high, low, differential, and manual reset settings are all just about the same. Their low is about 165, the high about 190, the differential at 15, and the manual reset at 200. The other three are working fine.

What can be causing this? What can I test or look out for? I appreciate your response. On 2017-01-29 by Steve S -

Reply:

Steve:

When the aquastat reset button is tripped off then the control found an unsafe condition (or the control is defective which is less likely).

The instructions for the Honeywell L4006E (the "E" means it has a high limit reset switch), include this advice for testing the aquastat limit switch:

In checking out the system, adjust the limit setting low enough so that the temperature of the controlled medium (water) reaches the high limit setting. When the limit setting is reached the Aquastat controller locks out and the burner shuts down.

When temperature of the controlled medium drops to the high limit setting, minus [the] differential [setting], push the manual reset button and the system should again be operative. Reset control to proper high limit setting.

To me this points out that if the control is not damaged, your system is either set to too-high a temperature or its temperature control is not working properly.

There might be a small temperature rise after a boiler reaches its limit due to residual heat in the steel or cast iron of the boiler but that ought not be enough to be causing trouble.

Your High (185) minus Diff (15) = 160. Reset the aquastat when the temp is below 160. Then if the problem recurs I suspect a defective temperature sensor or a defective control.

In the article above I'll be sure we include a link to the instructions for the AQUASTAT L4006, L4006E, L4007 HONEYWELL GUIDE [PDF]

Honeywell C99 controller keeps shutting down the boiler - I want to replace it

I have a Honeywell c99-100 with flame rod keep shutting down boiler gets to about 160 have to reset

lhood@mwmech.com Honeywell C99-100 with flame sensor boiler control having to reset boiler gets to 160 and trips out this control cost a lot what is my problem is their another control that I can use? On 2017-01-15 by Louis hood

by (mod) Before replacing a control I'd want to run some diagnostics

Louis

I can't say from just your brief e-text if the problem is with the Honeywell C99 controller, a flame sensor, or another control or burner operating safety problem.

I think by "flame rod" you refer to an igniter system for gas fired heating equipment. IF that's the problem, for example if the igniter is sparking but not igniting the flame, I would replace it using a compatible replacement, perhaps the Honeywell Q3400A1024 30-Inch Igniter Flame Rod Assembly. (About $40. U.S.D.)

Before replacing a control I'd want to run some diagnostics (such as are given in the control's installation and repair manual) and maybe change the flame rod.

...

Aquastat Replacement Need, Choices, Cost FAQs

Tip: See the broad-use replacement aquastat described at AQUASTAT L7224U UNIVERSAL

What is the difference is between the L4148e 1257, L4148E 1265 and the L4148e 1299 model aquastats?

Would like to know what the difference is between the L4148e 1257, L4148E 1265 and the L4148e 1299 model aqua stats. Thanks On 2016-11-09 by Gary

by (mod) - Here are the differences among the L4148e 1257, L4148E 1265 and the L4148e 1299 aquastats

Honeywell offers aquastat controllers for both oil and gas fired heating equipment such as hydronic (hot water) heating boilers and water heaters. Both single function (high limit or low limit are separate controls) and multi-function aquastats are provided.
The contemporary Honeywell aquastat line includes the

  • L6081 HI LO & Circulator controller
  • L7103 HI LO limits & circulator controller,
  • L7248 HI LO & Circulator controller & LEDs & EnviroCom communications
  • L7224U a universal replacemennt controller with an LED diagnostic display
  • 7224 aquastat with electronic temperature sensor, UL listed, controlling burner & circulator + LEDs
  • L4081 HI/LO circulator controllers for oil and gas boilers,
  • L8100 single limit control

I have not found an L4148 series such as in your question. Guessing you meant L8148 I note:

  • The Honeywell L8148 series aquastats are used on hydronic heating equipment and use an immersion-well sensor to inform the aquastast of the boiler temperature.
  • Honeywell L8148A aquastat switches line voltage to the burner, mounts horizontally, contains a HI limit only, uses a 24VAC thermostat
  • The Honeywell L8148E-1299 is a vertical-mount aquastat with an 15deg DIFF control and a 50VAC transformer. The limit control can switch both burner and circulator. This unit is designed for a low-voltage burner circuit.
  • The Honeywell L8148E-1265 is a vertical-mount aquastat with a 15deg DIFF control using a 24VAC transformer. Its high limit opens the burner circuit only. A remote low limit controller can be added.
  • The Honeywell L8148A-1017 is a horizontal-mount aquastat with a 8deg DIFF control. The controller switches both burner and circulators.
  • The Honeywell L8148J is a vertical or horizontal-mount aquastat switching a millivolt circuit (such as found on gas control valves)

Often an alternative case is available to convert vertical to horizontal mount for these controllers.

A link to the Installation and Operating guide and cross reference manual from Honeywell is give in the article

AQUASTAT CONTROLS - home

 

Are there re-built primary controls for boilers?

I had an issue with my boiler, i figured it out it was my Aquastat l8124

I called my local place and was told a used one was 190.00 rebuilt? I was told by another place there are no rebuilt aquastats.help!
ptsd1969@hotmail.com - Anon 10/3/12

Reply:

Some heating equipment suppliers can provide re-built as well as new primary controls. The folks who told you there are no rebuilt aquastats - well I'm not sure if that's because they didn't know or they didn't sell.

 

Does an error code mean I need a new boiler aquastat?

Is there anyway to reset the unit with an error code that says the assistant is bad or do I need to buy the whole new unit On 2018-08-13 by Clarence

Reply by (mod) -

Let's start with the brand and model of the control. Then we can look at the manual and the error code instructions.

by Anonymous Liberty II Aquastat Honeywell L7224/L7248 error code

The furnace is a liberty II, the aquasta is a Honeywell L7224/L7248 (electronic aquastat). The error code comes up 1.

Is there a way to reset the aquastat? Or is it common for them to go? Furnace is about 5 years old.

by (mod) - You probably do NOT need a new aquastat.

See the error code explanations and actions

at AQUASTAT L7224U UNIVERSAL DIAGNOSIS 

 

Can I retrofit a 15 year old boiler with a new Honeywell Electronic Aquastat?

I am thinking about retrofitting my 15 years old oil burner with new Honeywell electronic aquastat which includes Outside Temperature Reset module. Has anybody done it ?

This would allow me to adjust HI water temperature as a function of outside air temperature. They say this would result in 10-20% fuel savings. Has anybody done it ? Is it worth doing it ? Thank you. - Pavel 2/13/12

Reply:

The retrofit aquastat control you describe will function properly if properly connected. the actual heating fuel savings ... well that depends on quite a few variables. "Up to" claims, in advertising law, need be true only about 10% of the time.

 

What's the cost to replace an aquastat?

What does it normally cost to replace one? On 2018-01-29 by John weeks

Reply by (mod) - Typical Aquastat control cost

Currently (2025) I figure the ballpark of a typical boiler aquastat is between $150 to $400 for the control itself, depending on the model, and an hour of service tech time which might be anywhere from 60 to $100 - more if you live in an expensive area.

 

What's the repair if my Columbia boiler heats hot water but not the house?

My Columbia boiler (summer-winter hookup) will heat the hot water but does not seem to heat the house.

The water temp hits 220 degrees and shuts off before hitting the set temp. on the thermostat.

I just replaced the circulator and the problems still exists. Any ideas on what I'm missing here? Could it be the aquastat? (Nov 21, 2015) Sean said:

The aqua stat is a Honeywell L8124 L model and the Hi is set at 190, Lo is set at 160 and the Diff is set at 10.

Reply: aquastat behavior on a radiant slab heating system

Sean if the boiler heats up on response to a call for heat but the hot water is not circulating through the zones your system may be air-bound, or a circulator pump or zone valvce or circulator control may be inoperative.

Search InspectApedia.com for AIR-BOUND HEATING SYSTEMS to see details.

Sean said:
The boiler does not heat up on response to a call for heat from the thermostat.

The only time the boiler will fire up is when the water temp nears the lo temp. setting.

When I turn up the temp on the thermostat, it clicks at the thermostat and it clicks inside the aqua stat.

The pump does not turn on and neither will the boiler. Brand new pump and I'm positive that it's installed correctly and wired correctly. I have floor radiant heat in a ranch house on a slab that is slightly over 1000 sq. ft.

Reply:

Sean:

Have you checked the circulator relay?

Radiant heated slabs use a mixing valve to avoid making the floor too hot for comfort. So if the floors get warm and hot water is circulating through the radiant system, the boiler will not always turn on immediately on a call for heat. But if the boiler never fires up and the floors and boiler are cold and your thermostats are calling for heat, I'd start at

the AQUASTAT RESET BUTTON

Sean said:

Anonymous-At the risk of sounding stupid, where would the circulator relay be located?

Reply: where is the circulator relay?

Sean no questions are stupid - what's stupid is to be afraid to ask. The circulator relay on a single-circulator system is usually in the primary control or aquastat. On a multi-circulator system there may be separate individual circulator relay switches, usually mounted near the circulator pump. Follow the circulator pump power wire backwards to find the relay or controller for the circulator.

Sean said: Found the trouble: I need a new aquastat

I found the circulator relays and there is no voltage. Good call. Sounds like the aqua stat needs to be replaced. Right now I have a Honeywell L8124L Triple Aquastat Relay. Looks like they don't make that model anymore. Any suggestions on a similar model?

Reply: replacements for Honeywell circulator relays or aquastats

Good going, Sean;

For replacing the Honeywell L8124L aquastat, the company points to the Honeywell L8124A/C and L8148A - or you can contact honeywell directly: See , contact your Honeywell distributor,
call 1-800-328-5111 or visit customer.honeywell.com.
Automation and Control Solutions
In the U.S.:
Honeywell
1985 Douglas Drive North
Golden Valley, MN 55422-3992
In Canada:
Honeywell Limited
35 Dynamic Drive
Toronto, Ontario M1V 4Z9
www.honeywell.com

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