FAQs about hot water heating system circulator pumps and their installation, diagnosis, repair.

In this article series we list & describe both circulator pump relay controls and other heating system controls that manage or impact heating boiler circulator pump operation.

Circulator Pump Relays: 1 of 3 alternative ways to control hot water heat circulation

These questions & answers about circulator relay controls or switches (used to turn hydronic heating system circulators on or off) were posted originally

at CIRCULATOR PUMP RELAYS & OTHER CONTROLS - be sure to see the advice and circulator controls discussed there.

[Click to enlarge any image]

On 2017-12-14 by (mod) - circuit breaker to the boiler circulating pump was tripped

I would go to the boiler and disconnect power to the primary control. And turn the breaker back on.

If it Trips Again then since you've disconnected everything that your heating system you would expect the problem to be in the circuit wiring itself.

On 2017-12-14 by Jerry

When I turned the 2 thermostats up to start heating the outbuilding this fall, without response, I found the circuit breaker to the boiler circulating pump was tripped, and continued to trip immediately after each time I reset it.

The system is about 16 years old-2 zone, has a Honeywell R8285a-1048 relay and a Grundfos type UP 15-42f circulating pump. Where would be the best place to start troubleshooting this problem?

On 2017-02-13 by Anonymous

One zone is not bringing the temperature up to the thermostat setting and we atre in the middle of this storm, the other two zones are working great???

On 2016-12-20 by (mod) -

Michael:

5 psi is abnormally low - if the gauge is accurate there's probably a leak and also a defective water feeder valve. At low pressure the circulator may not be able to push hot water up to baseboards at higher levels.

On 2016-12-18 by Michael

Peerless boiler firing hot water at showers...baseboards cold not heat..no air in lines...taco circulator pump only 5 lbs pressure on gauge at furnace....is there a relay to check if it's working

On 2016-02-01 by John

My single circulator pump has about 90 VAC coming into it. This seems a little low. The burner fires normally and I get some circulation. Is my Aquastat bad?

On 2015-12-31 by (mod) -

SUre Greg; click to show the REFERENCES at the end of this article and look into

Installation Guide for Residential Hydronic Heating Systems
Installation Guide #200, The Hydronics Institute, 35 Russo Place, Berkeley Heights, NJ 07922

On 2015-12-31 by Greg

Is itpossible to get a piping and an electrical drawing for a hot water heating using circulating pumps and relays?

On 2015-11-27 by (mod) -

Tim, usually each pump has its own start relay. One of these or its controlling thermostat mat be bad.

On 2015-11-27 by Tim

Switch relay r8845u won't start 1of 2 circ pumps

On 2014-06-04 by (mod) -

Jeff

Thanks for the clarification. Your view is reasonable.

I think tech figure it's easier and safer to swap out multiple old parts (even if some may be ok) than to have to return to the job. Considering service call costs it may be a less expense approach overall

On 2014-06-03 03:55:15.755960 by JeffHOA

Daniel, I heard from our maintenance manager who is coordinating the boiler repair. He says: "The clock is to time and signal cycles (eg, pre purge, attempt to light, post purge, etc. ). The boiler company recommended the clock be changed out along with the failed relay." Sounds like it's not that expensive, but funny that something like an electronic clock would need to be replaced. Thanks for your help.
Jeff

On 2014-06-01 17:45:33.584900 by JeffHOA

Thanks, Daniel - will check on the clock and let you know. Appreciate the validation on the relays.

On 2014-06-01 14:31:16.857940 by (mod) -

Jeff,

Sorry I don't know what the tech is referring to either.

Relays that control the switching of equipment might need replacement if the relay was burned or damaged, and such damage could occur in the time you cite. I don't know what clock they're talking about. Perhaps you could ask that someone point out the part to you - note its brand and model number and let us know.

Daniel

On 2014-06-01 14:31:15.751750 by (mod) -

Jeff,

Sorry I don't know what the tech is referring to either.

Relays that control the switching of equipment might need replacement if the relay was burned or damaged, and such damage could occur in the time you cite.

I don't know what clock they're talking about. Perhaps you could ask that someone point out the part to you - note its brand and model number and let us know.

Daniel

On 2014-05-31 19:02:00.535850 by JeffHOA

Hi - we have a two-stage boiler in our 4-unit mountain condo unit that provides hot water for consumption as well as for sidewalk ice melt (heated glycerine lines). The unit is about 8 years old, and we're being told by the company that services it we need to replace two relays and a "clock" for each boiler stage.

Is 8 years a reasonable lifespan for relays? And do you have any idea about what is the "clock" that needs replacing? Thanks!

On 2014-03-03 04:38:29.013310 by (mod) -

Matt: maybe using a mechanic's stethoscope or even a simple pen or iron rod you might be able to decide if the buzzing is in the motor itself (bad bearing, new motor time) or in the circulator relay (replaceable electrical part)

On 2014-03-02 by Matt - humming buzzing cirulator pump

My circulator pump (Taco 007) started humming or buzzing a few days ago.

But hot water is definitly getting circulated to baseboards. So it appears to be working

Besides the buzz the only thing unusal is that is seems some baseboards are taking longer then usual to fully heat. But I can't really verify that. I may just be imagining that.

On 2014-02-20 by (mod) -

Gary that sounds correct. When heat is running the boiler will shut off when its internal temperature reaches the HI limit.
The circulator will continue to run until the call for heat is satisfied at the room thermostat.

When heat is not already running, when the room thermostat calls for heat the thermostat turns on the circulator to send hot water to the heating zone baseboards or radiators; as returning cool water drops boiler temperature the boiler's burner will then turn on.

On 2014-02-19 by gary

Is the circulate pump still running for 2-3 munites after the boiler shuttoff ?
its starts running for 30 seconds before the boiler turns on

On 2014-02-12 22:23:45.056440 by (mod) -

Circ:

It sounds as if there may be a problem with the circulator relay or even the pump itself;

On 2014-02-11 14:11:20.714820 by circulating pump

circulating pump stop working but when I turn off and back to on the furnace then it starts working.

On 2012-12-18 04:35:26.634726 by Possible faulty aquastat

Sorry, that's a Honeywell 7224 aquastat.

On 2012-12-18 04:34:35.573310 by Possible faulty aquastat

DanJoe,

Furthermore, I have checked the aquastat and the TT and C1 led's are lit and I also get a reading of 120V across C1 and C2. Does this suggest a faulty circulator instead ?

I believe my zone valves are open and I bled the entire system (3 zones) before I started looking at the aquastat and circulator.

Thanks.

On 2012-12-18 03:59:41.872588 by Possible faulty aquastat

DanJoe,
I had a new aquastat fitted 3 years ago when the old one failed to start the circulator and my pipes froze. The new one seems to have failed in the same way.

Is there anyway to force the aquastat to tell the circulator to run so I can check to see if the relay is switching to send 120V to the circulator pump ? I don't want to have to pay my plumber $400 for a $100 part.

On 2012-03-11 01:39:26.524525 by (mod) -

Circ:

I don't have enough info from your question to make a real answer, but perhaps you're seeing the heating boiler's burner turn on under control of the low-limit - for example if you crossed the controls and set the "lo" above or anywhere less than 20 degF below the HI.

What happens in that case is that the LO turns on the boiler and will also force OFF the circulator until the boiler has heated up again.

On 2012-03-08 01:01:49.371853 by circulator pumps

Seems like the oil furnace cuts in to cut out the circulator pump! Not all the time but at times that is what happens. Was wondering if it is a thermostate problem?

...

Continue reading at CIRCULATOR PUMP RELAYS & OTHER CONTROLSor select a topic from closely-related articles below, or select a topic from the closely-related articles below, or see the complete ARTICLE INDEX.

Or see CIRCULATOR PUMP WON'T START

If you are not getting any heat at all out of a cold baseboard or radiator, see COLD HEATING RADIATOR REPAIR (hot water / hydronic heat)

If the heating boiler itself if does not turn on in a response to a call for heat see NO HEAT - BOILER.

Or see these

Hot Water (Hydronic) Heating Boiler Circulator Articles

• BOILERS, HEATING - home
• BOILER CONTROLS & SWITCHES
• CIRCULATOR PUMPS & RELAYS
• BELL & GOSSETT B&G EQUIPMENT MANUALS & CONTACT
• CIRCULATOR PUMP BASICS
• WHAT GOES WRONG WITH HEATING CIRCULATORS?
• CIRCULATOR DIAGNOSTICS
• BYPASS a BAD CIRCULATOR
• CIRCULATOR COSTS
• CIRCULATOR NOISES
• CIRCULATOR OPERATION CHECKS
• CIRCULATOR PUMP LEAKS
• CIRCULATOR PUMP MANUALS
• CIRCULATOR PUMP MOTOR or BEARING FAILURE
• CIRCULATOR PUMP MOUNT LOCATIONS
• CIRCULATOR PUMP MOUNT POSITION
• CIRCULATOR PUMP RELAYS & OTHERS
• CIRCULATOR PUMP RELAY CHATTERING
• CIRCULATOR PUMP WON'T START
• CIRCULATOR PUMP WON'T STOP RUNNING
• CIRCULATOR PUMP RUNS INTERMITTENTLY
• CIRCULATOR PUMP SPEED SELECTION & ADJUSTMENT
• CIRCULATORS VARIABLE SPEED
• MULTIPLE CIRCULATORS HOW TO HOOK UP
• MULTIPLE HEATING ZONE CONTROL
• TACO CIRCULATORS & CONTROLS
• WEAK HEAT, WEAK CIRCULATOR, TOO COOL
• CIRCULATOR PUMPS vs ZONE VALVES

Suggested citation for this web page

CIRCULATOR PUMP RELAY FAQs at InspectApedia.com - online encyclopedia of building & environmental inspection, testing, diagnosis, repair, & problem prevention advice.

Or see this

INDEX to RELATED ARTICLES: ARTICLE INDEX to HEATING BOILERS

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Citations & References

In addition to any citations in the article above, a full list is available on request.

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