Hot water heating system zone valve installation wiring questions & answers:

Frequently-asked questions (and answers) about wiring heating zone control valves and zone controllers from all manufacturers.

This article series describes how to wire up heating zone valves. 

We include wiring diagrams and installation instructions for most zone valve model and multi-zone controllers, and we describe special wiring problems that can occur if you mix different types, brands, or models of heating zone valves on the same hydronic heating (hot water heating) system.

Page top photo: Honeywell V8043 Zone Valve showing a wiring connection terminal block.

Zone Valve Wiring Hookups for Hydronic (Hot Water) Heating Systems

These Questions & answers about wiring up heating zone valves & zone controllers, were posted originally

at ZONE VALVE MANUALS & WIRING INDEX

Annotated photo: Honeywell V8043-1000 series zone valve showing basic information about the red & yellow wire connections discussed on this page.

[Click to enlarge any image]

Taco ZVC403 Zone Controller Wiring & Troubleshooting.

Question: why does one of my zones shut off after just a few seconds?

... The other issue [besides the relief valve leak we discuss

at RELIEF VALVE LEAK DUE TO EXPANSION TANK ] I'm having is with my 3 zone 1 pump radiant heat system.

Zones 2 and 3 work fine, but when zone 1 activates, the pump turns on for about 5 seconds, then shuts off

I'm using a Taco 3 valve control module and a Tekmar 360 mixing control.

This system is about 8 years old, and has mostly worked fine until lately. On the Taco, both the zone 1 thermostat and zone valve LED's illuminate.

Any suggestions or tips would be most welcome. - Karl Peterson by private email 2017/12/09

This discussion is indexed as ZONE CONTROLLER TACO ZVC403

More details about this system:

My boiler is an embassy industries Cosmogas BMS 15/29, and I have a manual. It is for both domestic hot water and heat in a radiant heat floor.

[The Cosmogas boiler manual for this heater/water heater gas fired combo boiler as well as company contact information is at COSMOGAS® boiler / water heater combo manuals - thanks to Karl for providing this document - Ed.]

Below is a photo of the front panel. It is supposed to have a minimum of 12 psi, and a max of 30psi according to the manual, but the relief valve is at 50psi (another photo below.)

At rest, the pressure is indeed about 12-15 psi generally, but after 2 or three cycles of the heater heating up water for the radiant heat, the pressure climbs to about 45psi, and the valve starts to bleed off pressure.

Its done this all last heating season, and possibly the previous season as well. it never does this in the summer time (or when the heat is off) and as I mentioned previously, it didn't do this at all for the first 6 or 7 years it was installed. There is no banging or hammer noises.

[Click to enlarge any image] Above: Zurn Model P1000A temperature/pressure relief valve rated for 200,000 input BTUH and opening at 50 psi. This TPR is rated to handle thermal expansion of hot water and complies with ANSI Z21.22 / CSA 4.4 relief valve specifications.

The Taco [multiple heating zone controller ] is a ZVC403, and yes, the green LED is always on, and the zone 1 issue is after both the yellow/orange thermostat LED and red Zone Valve LED are illuminated. The pump starts for about 5 seconds, then shuts off.

Although, I did notice that at one point yesterday, zone 1 was the only zone calling for heat, and the circulation pump was running normally.

However, about 15 minutes ago, it was back up to it's new trick of only turning the pump on for 5ish seconds and then shutting off again.

At the time of this photo, the pump was not running, and there was no domestic hot water demand.

Reply: diagnosing a too-short zone-on cycle & the Taco ZVC403 control

I have not encountered the "just 5 seconds on" problem you describe so I can only speculate. The LED indicators you describe sound normal per the documentation I'll cite below. .

Since there's a common circulator pump and controls one might naturally suspect either the zone valve itself ( a bad connection, loose wire), or a bad control module in the Taco master zone control.

Take a look at the system temperatures and at whether or not you are using domestic hot water when this short-on-zone problem is occurring.

Watch out: also look for a leak into the hydronic system that could be pushing the pressure up abnormally, such as a leaky tankless coil (if you have one).

You might want to give Taco a call directly to ask about this situation as I'd bet a beer that their engineers have encountered it before.

Or we can wait a few days: I have posted this question with Taco's customer technical support and asked for an opinion, the support rep responded immediately, and has said that he is not familiar with the problem you describe but he also asked for wiring photos - now sent from those you provided.

In the U.S. contact Taco at Taco Comfort Solutions, Inc. 1160 Cranston St. Cranston, RI 02920 Phone: (401) 942-8000 FAX: (401) 942-2360 International readers should also use this contact address.

In Canada contact Taco at Taco (Canada) Ltd. 8450 Lawson Road Unit # 3 Milton, Ontario L9T 0J8 CANADA Phone: (905) 564-9422 FAX: (905) 564-9436

Watch out: some multiple zone controllers like your Taco permit assigning one of the zones as a "priority" zone - typically used to assure that an indirect fired water heater for domestic hot water supply will get priority over heating zones. That controller will turn off zones 1 and 2 when zone 3 is calling for heat if zone 3 is set up as "priority zone".

Watch out: also some digital thermostats can fail to work properly when connected to this zone controller.

The instruction manual and wiring diagram for your Taco ZV403 Zone Valve Controller will be one of these two documents

• TACO ZVC403 ZONE VALVE CONTROL WIRING & MANUAL [PDF] (2013) # 102-391 retrieved 2017/12/10 original source: http://www.taco-hvac.com/uploads/FileLibrary/102-391.pdf
  The light codes and zone priority for this controller are excerpted below:
  
  Operation/External Diagnostics: When any thermostat calls for heat, the appropriate zone valve is energized and the yellow light goes on. When the zone valve is fully open, the red light goes on and energizes the end switch relay. The green light should always be on, indicating that power is connected.
  
  Priority Operation: When zone 3 is switched to the priority setting and is actuated, all other zones will stop operation until zone 3 is satisfied. When zone 3 is not switched to priority, all zones will operate independently.
  
  Note: When a circulator is used on the priority zone instead of a zone valve, jumper 3 and 4 of the priority zone.
• TACO ZVC403 ZONE VALVE CONTROL WIRING & MANUAL [PDF] (2006) # 102-089 retrieved 2017/12/10 original source: http://www.taco-hvac.com/uploads/FileLibrary/102-089.pdf|
  The light codes for this controller are given herein:
  
  Operation/External Diagnostics: When any thermostat calls for heat, the appropriate zone valve is energized and the yellow light goes on. When the zone valve is fully open, the red light goes on and energizes the end switch relay. The green light should always be on, indicating that power is connected.
• VIDEO of COSMOGAS BOILER OPERATION [85MB file: Cosmogas-Boiler-Overpressure.mp4 ] - OFFLINE, AVAILABLE on REQUEST - contact us - illustrates the sequencing of the TACO ZVC403 zone controller operation and LED light sequencing
  
  made during diagnosis of
  
  RELIEF VALVE LEAK DUE TO EXPANSION TANK

Taco's equipment manuals and contact information are

at TACO HVAC components & controls

On 2016-12-31 by (mod) - honeywell minizone system with heat pump wiring & actuators

Thanks for the feedback, Randy, that will help others.

For other readers, the "ARD" that Randy describes is perhaps a Honeywell Automatic Round Damper used on a forced-air system not a hot water zone valve system such as those on the page ZONE VALVE MANUALS & WIRING INDEX

The company provides models described as power-close, spring-open models ensure low leakage while controlling circulating air in heating, cooling and ventilation systems.

On 2016-12-31 by Randy

I had 3 bad actuators they have been replaced with new ARDs

With the honeywell minizone system with heat pump does it matter on thermostats or do you need a master and 2 slaves I have 3 zones right now my zones aren't closing like they are supposed to

On 2016-11-29 by Ruben

I am trying to wire a Honeywell zone valve and have a red and white wire coming from my thermostat and I need the correct wiring as I see no 24v transformer I think it is in the broiler room in a condo building. Central broiler for all units.

On 2016-10-12 0 by Anonymous

Hi my cir pump is running all the time in my heating system

 

On 2016-08-22 by Walter Hawn

Thanks you for this site. Been fussing how to wire a Honeywell L8124E with two V8043E zone valves and one circulator. Your site verified that I'd gotten it worked out correctly, so now I can go ahead!

Moderator reply: how to wire thermostat to honeywell zone valves

Anon: see

• HONEYWELL ZONE VALVE INSTRUCTIONS - wiring connections
  
  And also
• HONEYWELL CONTROLS On HVAC Equipment, thermostats, primary controls, zone valves

On 2016-06-01 by Anonymous

I need to know how to wire thermostat to honeywell zone valves and then to a Weil-McLain noiler

On 2016-02-01 by John

I am seeking to verify that the V8043E Zone Valves I bought are compatible with our L8124A Aquastat on my oil boiler.

Figure 13 of the manual that came with the zone valves would seem to indicate they are compatible as Honeywell shows them together. But I remain concerned because the Aquastat boiler control unit is noted at 120 volts and the V8043E Zone Control is 24 Volts.

On 2015-12-15 by Shawn

Any idea how to hook up a 3 zone system with circulating pump to the boiler?

On 2015-11-21 by (mod) -

Thanks for helping-out Radiant.

On 2015-11-21 by RadiantGuy

@Marie, I am not sure what a elecdiccircuit is. In a hydronic radiant install with two zones, if one works and the other doesn't then the issue is most likely the zone valve controller for the zone that isn't working. It could also be the thermostat for the zone that isn't working.

On 2015-11-20 by Marie

I have one floor house with two zones one side heat goes on the other does not,.

Do I have two electdiccircuits? Could one circuit not be working

On 2015-11-09 by (mod) - install a bell and Gossett model SZV-075N-4WE snap zone valve for an upstairs hot water heat system.

Farm

As Bob Dylan said many times, I believe that can be easily done - and [without having to hitchhike] out on Hwy 61: you need a thermostat for the upstairs heating zone,

wire from the thermostat down to the location where you're installing the B&G circulator, maybe a 24VAC transformer to power the thermostat if you don't already have one installed nearby, and a separate zone control relay to turn the circulator on and off under thermostat control.

When the TT calls for heat the circ will run and send hot water around the system on the zone to which it's connected (provided it's not shut off from water by a valve somewhere).

The drop in temp at the boiler will turn the boiler on as needed.

Perhaps I misunderstood something?

On 2015-11-08 by farmerdave

I would like to install a bell and Gossett model SZV-075N-4WE snap zone valve for an upstairs hot water heat system. It’s not clear to me how it should be wired into your Azel SZ-V6 zone controller.

I need to wire the zone valve separate from the 6 zones I already have setup.

On 2015-10-01 by Anonymous

And why do you not want zone control (thermostats ) on each zone?

thats the point of zoning! Anyways - sounds like you have multiple issues that would be better served by having a professional look at.

Do you have a mixing valve installed for the radiant floor? or are you just running high temp water there? Lots to know about doing this properly.

On 2015-10-01 by Anonymous

Hey Guys - transformers are rated for Va, Zone valves are also rated at specific Va,

you cant say 1 transformer will power 5 zone valves, what if its a 25 Va transformer? or a 40Va? both sizes are quite normal...

On 2015-07-25 by (mod) -

Typically Sam one transformer can power up to a maximum 5 zone valves. Check the total VAC provided by your transformer against the total VAC draw should all four of your zone valves try to open at the same moment.

Normally one thermostat ought to be able to switch two zone valves on by using common connections - power is coming from the transformer.

The thermostat is basically operating as a low voltage switch. But it might be significant that I have not seen this example in any of the wiring diagrams for zone valves.

Click on the PDF files given at ZONE VALVE MANUALS & WIRING INDEX to see zone valve and thermostat wiring diagrams in more details. You'll also find our contact information for Honeywell to ask further.

On 2015-07-25 by sam

I have 4 Honeywell zone valves and 2 thermostats I want to wire 1 tstat to 2 zonevalves not sure how to do

On 2014-11-27 by (mod) - zone valve wiring error - both zones open when just one thermostat calls for heat

Mark

I agree that
it sounds as if there is indeed a wiring error.

Check that each thermostat only talks to one zone valve. That's where I'd start.

The thermostat wires open the zone valve.
When the zone valve is open an end switch turns on the circulator.

Also check that neither zone valve is manually latched "open"

On 2014-11-27 by Mark

I have a Navian combination boiler/hot water heater and I'm trying to wire it to a Honeywell switching relay and Honeywell zone valves. There is an upstairs zone and a downstairs zone. When I turn it on, both zones open, but the upstairs zone is only calling for heat.

On 2014-10-22 by (mod) - room gets too hot, heat doesn't turn off

Anon and Scott:

Check for thermostat wires that are shorted together - always calling for heat.

A zone valve stuck open or opened manually can give the same overheating trouble.

A thermostat improperly located on a cold wall or in a draft could also be a problem.

See these diagnostic articles

• HEAT WON'T TURN OFF
  • FAN WONT STOP - THERMOSTAT SWITCH
  • HEAT STUCK ON BY CONVECTION
  • THERMOSTAT WON'T TURN OFF

On 2014-10-21 by Anonymous

I have the exact same problem, did you a answer to your dilemma?

On 2014-10-14 by scott furey

I just put a new thermostat in hoping to solve this problem. It has not helped.

No matter what temperature I set my thermostat to, the room gets oppressively hot. Can the zone valve be wired incorrectly?

Or can you wire it to remain on full time? I'm at my wits end and don't want massive bills as a result. Thanks in advance.

...

Continue reading at ZONE VALVE WIRING - topic home, or select a topic from the closely-related articles below, or see the complete ARTICLE INDEX.

Or see ZONE VALVE WIRING FAQs-2 - more-recent Q&A about wiring heating zone valves and switching relayts

Or see these

Zone Valve Articles

• CIRCULATOR PUMPS & RELAYS
• ZONE VALVES, HEATING - home
  • DISSOLVED OXYGEN DAMAGE CONTROL
  • ZONE CONTROLLER TACO ZVC403
  • ZONE VALVE BANGING or BACKWARDS
  • ZONE VALVE MANUALS & WIRING INDEX
  • ZONE VALVE SIZE vs GPM

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ZONE VALVE WIRING FAQs at InspectApedia.com - online encyclopedia of building & environmental inspection, testing, diagnosis, repair, & problem prevention advice.

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INDEX to RELATED ARTICLES: ARTICLE INDEX to HEATING BOILERS

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