FAQs about heating zone circulator pump wont' stop running.

This article series explains how to diagnose & fix a heating circulator pump that runs even when we are not asking for heat.

FAQs Heating Zone Circulator that Won't Stop Running

These questions and answers about troubleshooting and fixing a heating zone circulator pump that won't stop were posted originally

at CIRCULATOR PUMP WON'T STOP RUNNING - you may want to check the advice given there.

See our index to questions & answers about installing or repairing heating zone circulators at

CIRCULATOR PUMP REPAIR FAQs - index

Circulator pump won’t stop when I turn its power off

Circulator pump won’t stop when I turn it off it’s continues to run I changed thermostat what else should I do? On 2020-01-03 by Jaime

by (mod) - check / replace the electrical power switch

Jaime

Watch out: Any electrical device that won't turn off when you think you have turned off its electrical power supply is dangerous, a potential fatal shock or fire hazard.

If you are turning off electrical power to the circulator and it won't stop then we know that there is at least a bad electrical switch that needs to be replaced.

Lets next look through the diagnostics on the CIRCULATOR PUMP WON'T STOP RUNNING page

as that is an organized way to step through causes of a circulator pump that just continues to run no matter what.

Circulator Pump Will Not Shut Off

Three Taco zone valves on one Taco circulator pump. All getting proper voltage and confirmed working. Boiler hi-lo set& working properly.

Regardless of zone demand for heat or satisfied & regardless of boiler temp, and confirmed 110V across C1 & C2 terminals, C1 ( Honeywell L7224) indicator & pump stay on! This is a new behavior, and was not the case before.

Even when I power down the system, wait 30 seconds or even 2hrs, when reenergized, 10 seconds of silence, C1 indicator light goes on, followed by a relay click, and circulator turns on. This is with no TT demand and BT above limit.

Absolutely frustrating as to why the Aquastat is now turning on the relay/circulator for no need or reason.

The MAJOR CONCERN is, the pump is on the return side, in-between closed zone valves and boiler. A total distance of <2'. not much room for relief to the impeller, sucking away like someone trying to suck a just served wendy's shake through a straw! the motor is very hot.

Then i've seen on a couple of discussion sites, "no harm will come to the circulator". sounds like b.s. from a taco sales rep to me.

Question is, what happened? why is the circulator suddenly running non-stop? is there a fix? btw, it is rather cold, 15 - 20 outside, & no, this doesn't have an outside sensor. but we've had colder days.

For now I'm running heat, and when up to temp, manually turning off boiler power at top of stairs, sleeping in recliner for 2hrs. waking up to turn on the heat for another warming. lather, rinse and repeat.

I would sure appreciate hearing your valued advice? On 2018-02-04 by W.Sharpe -

Reply by (mod) - Remove thermostat wire connections to start diagnosis

First step: where are you: country and city. IN some locals such as most of Canada, circulators are wired to run continuously during the heating season. The thermostat turns the boiler on or off. This gives more even heat distribution and helps avoid frozen zone piping.

Next step: continue diagnosing by removing thermostat wires at the circulator or Zone controller

If the circulator stops then the thermostat was calling for heat - OR its wires are shorted so as to appear to be calling for heat.

Of course if the circulator is running but no heat is being delivered then start by checking to see if the boiler will run.

If the boiler is hot and the circulator is running but no heat is being delivered to the radiators or baseboards

then see AIR-BOUND HEATING SYSTEMS - home

 

Circulator pump running continuously after the boiler shut off.

I noticed my circulator pump running continuously after the boiler shut off. Only after turning of the system power did the circulator pump stop running and it started running again after turning the power back on.

After reading the comments here, I used my flashlight to tap the circulator pump in hopes of freeing a stuck relay, and it worked.

Would it be reasonably safe to assume the electrical relay on the pump is sticking and can the relay be serviced or replaced without replacing the pump itself? The pump is less than 10 years old. I live in the San Francisco area. Thanks (May 18, 2015) Lee said:

Reply: checking out a Grundfos UPS 15-42 and UPS 26 Circulator Pump Operation

Lee that sounds reasonable to me.

And it's worth making the repair as a relay that sticks today may stick "off" sometime when you're not around and would have wanted heat to be reliably "on" in the building.

If you replace just the relay (which is possible on some controls) I'd like to examine the old one - you can find my mailing address at the CONTACT link at page bottom.

Really?: Note that in some boiler installations, particularly as is custom in many areas of Canada, the circulator runs constantly when the heat is "on" and it's the thermostat's job just to turn the burner on and off.

Lee said:
Hi Daniel. Thanks for your quick response. Give me a few days to check it out and I'll get back to you. Thanks again. I checked out my pump and found: It's a Grundfos Type UP 43-75BF 216. I took off the side panel where the electrical connections are made and only found a capacitor, no relay that I can see.

So, again, I assume it must have an internal relay? At this point, I'm not sure what to do, other than replace the pump, which I would prefer not to do. Any thoughts?? Lee

Reply:

Lee that pump has a permanent split capacitor type motor with an internal thermal overload circuit - the problem could be a connection or an internal component.

Before replacing the motor I'd double check for a loose splice or wire connection. If it's not working you should be able to replace just the motor component. If your model is a multi-speed version also be sure the speed switch is not loose or damaged.

I should have said first to follow the thermostat wires - those will take you to the circulator relay which will answer the "where is it?" question.

Also check - with power disconnected - that the pump shaft rotates freely. Here is what Grundfos says about that:

When UPS 15-42 and UPS 26 pumps are first started, the shaft may rotate slowly until water has fully penetrated the bearings. If the pump does not run, the shaft can be rotated manually.

To accomplish this, switch off the electrical supply, and close the isolation valves on each side of the pump. Remove the indicator plug in the middle of the nameplate. Insert a small flat blade screwdriver into the end of the shaft, and gently turn until the shaft moves freely.

Replace and tighten the plug. Open the isolation valves and wait 2 to 3 minutes for the system pressure to equalize before starting the pump. NOTE: After a long shut down multi-speed pumps should be started on speed 3 and then adjusted to the regular setting. The UPS 15-42 has automatic function to assist in restart. 

Lee said:
Daniel, thanks for your comments and advice! Much appreciated! I'm fairly sure this is a single speed model. Thank you again!

Reply:

Yep - I took a look for more diagnostic tips in the Grundfos installation guide, there's not much.

Lee said:
As I mentioned, the pump works fine, it just won't shut off!

Reply:

Don't forget to check for control wires shorted together and check for a bad circulator relay.

Lee

Dan, I wanted to followup on this. After shutting off all power to my system, I checked and retightened all electrical connections. Checking through my AO Smith boiler manual,

I located the Relay and High Limit control box, which is mounted on the front of my unit under the front cover panel.

After removing the control box cover, I saw the circulator relay that is clearly marked "circulator".

So, it was a little dusty and I could clearly see the relay contacts. So, I took a spray can of electronic contact cleaner, and, following the directions on the can of spray, cleaned the relay

I've turned the power to the system back on and off numerous times and it appears to be operating normally now, ie, the circulator shuts off when the boiler shuts off. So, I think my problem has been solved, but I will monitor it for the next week to insure proper operation. Thanks for your help and a great website!.....Lee

 

Circulator Pump Will Not Shut Off

Three Taco zone valves on one Taco circulator pump. All getting proper voltage and confirmed working. Boiler hi-lo set& working properly.

Regardless of zone demand for heat or satisfied & regardless of boiler temp, and confirmed 110V across C1 & C2 terminals, C1 ( Honeywell L7224) indicator & pump stay on!

This is a new behavior, and was not the case before.

Even when I power down the system, wait 30 seconds or even 2hrs, when reenergized, 10 seconds of silence, C1 indicator light goes on, followed by a relay click, and circulator turns on. This is with no TT demand and BT above limit.

Absolutely frustrating as to why the Aquastat is now turning on the relay/circulator for no need or reason.

The MAJOR CONCERN is, the pump is on the return side, in-between closed zone valves and boiler. A total distance of <2'. not much room for relief to the impeller, sucking away like someone trying to suck a just served wendy's shake through a straw! the motor is very hot.

then i've seen on a couple of discussion sites, "no harm will come to the circulator". sounds like b.s. from a taco sales rep to me.

question is, what happened? why is the circulator suddenly running non-stop? is there a fix? btw, it is rather cold, 15 - 20 outside, & no, this doesn't have an outside sensor, and we've had colder days.

for now I'm running heat, and when up to temp, manually turning off boiler power at top of stairs, sleeping in recliner for 2hrs, waking up to turn on the heat for another warming. lather, rinse and repeat.

your valued advice? On 2018-02-04 by W.Sharpe

by (mod) - Check this diagnostic procedure

WS

See the repair procedures

at CIRCULATOR PUMP WON'T STOP RUNNING

and let me know what questions remain

 

Heater won't shut off even if I turn down the thermostat

I have a heating system (propane) with 2 zones. up and down as well as my hot water. i dont have a controller system (digital) recently it got very hot in the downstairs

I removed my wires from the thermostat to see if that was causing it constantly request heat. Not the case. even replaced it due to wife thinking it was the problem. only way to stop the heat was to turn off my main valve to that zone. there is two separate valves

and i shut them both off. then that night i turn them back on, it heats up the space, (to hot) and i shut the valves off again.

my other zone and hot water have no issues so i know its with just that zone and probably a valve stuck open. however at this point my knowledge shrinks and not sure how to proceed. thanks for any help in the matter (Mar 20, 2015) jamie

Reply:

Jamie

Try disconnecting the thermostat wires at the heater end not the thermostat end. If that stops heat then the thermostat wires are shorted.

Our detailed troubleshooting guide for the problem you describe is

at HEAT WON'T TURN OFF  - please be sure to read over the advice given there.

jamie said:

Dan, would it be best to disconnect at the zone valve? if heat still continues i assume zone valve issue?

Reply:

Ah ok so here's the thing:

If TT wires are crossed you may be calling for heat all the time. Disconnecting the TT wires would prove that.

Details are at THERMOSTAT WON'T TURN OFF 

A different problem is a zone valve that doesn't shut. Disconnecting wires won't fix that.

If the TT wires are disconnected - you can do it at the zone valve - and the valve stays open, you'll find hot water passing through the valve and the pipes will stay hot on both sides of the valve and heat will show up even on the return point of that zone to the boiler.

Some zone valves can be manually opened (by a lever) but not necessarily forced closed.

So if this is the trouble you'll need a new zone valve.

Those details are at ZONE VALVES, HEATING - zone valve repair steps.

Jamie said:

How easy is it to replace one of these valves. This is out of my comfort zone and wondering if just replacing the valve would be easier then trying to trouble shoot the issue. I am confident it is the valve and not wiring, house is only 5 years old new.

Reply:

Jamie it's not technicalliy difficult if you know how to drain a heating boiler safely and cut and solder or connect pipes and electrical wires.

Watch out: let's not start replacing parts before we are confident that your "heat won't shut off" problem has been diagnosed correctly.

Chances are the job will be faster and easier and maybe cheaper if you hire a pro.

 

Boiler keeps kicking on and baseboards stay warm when they shouldn't

(Dec 11, 2014) Anonymous said:
My oil fired hot water boiler is equipped with 2 Taco 007 circulators supplying hot water to 2 zones of the house as well as providing domestic hot water for the shower and sinks.

Recently I've noticed that even with the zone 1 room thermostat set way low, the boiler continues to kick on and keeps the baseboard heaters warm. Does this sound like a problem with the circulator pump?

The service valve located on the boiler side of the pump seems to have some rust build up at its connection with the water pipe leading from the boiler itself. Might that be the issue? Any help someone could provide is greatly appreciated.

Reply:

Anon at the end of this page or in the ARTICLE INDEX found there see

CIRCULATOR PUMP WON'T STOP RUNNING

for diagnosis and repair advice.

 

How do I turn off circulator pumps that always run?

Looking to find a way to turn off circulating pumps if the source water temp is below the thermostat setting, currently the pumps will run no matter the source water temps, effectively cooling my home during cold weather. On 2017-12-03 by Rick W.

Reply by (mod) -

Rick, on a conventional aquastat that sports a HI LO and DIFF setting, if the boiler temperature falls below the LO the circultators will not run.

See AQUASTAT HI LO DIFF SETTINGS

But note that in some areas such as most of Canada, circulator pumps are set to run continuously during the heating season both for more constant temperature control and to reduce the risk of freezing pipes. In those installations the room thermostat simply turns the boiler on and off as needed.

 

Does a circulator that never stops increase electricity & oil bills

Would a faulty circulator pump that was not shutting off cause excess use of oil and electricity? - On 2017-05-01 by Beth Brown

Reply by (mod)

In a typical U.S. installation, it's the room temperature that will call for heat or not, so even if the circulator is running, the oil burner on your boiler won't turn on if there is no call for heat. Yes the circulator motor uses a bit or electricity when running.

In Canada, circulator pumps are set to run continuously during the heating season both for more constant temperature control and to reduce the risk of freezing pipes. In those installations the room thermostat simply turns the boiler on and off in response to a call for heat.

Should I shut down my circulator while the boiler is off, waiting for repair?

I have a boiler that is down and want to know if the circulation pump (multi zone) should be turned off of left on while the system is fixed (2 days)? Any harm either way? - On 2017-12-28 by SteveC

Reply by (Mod) -

Steve, IF you are in freezing weather and IF there are no water leaks anywhere in the system, then leaving the circulator pump running and the zone valves latched "OPEN" can reduce the risk of frozen heating pipes, and should not do any harm.

Keep in mind that for the repair the circulator may need to be turned off - something your service tech can handle.

Watch out: but if there are water leaks anywhere, you should leave the circulator off to reduce water damage to your building. - Daniel Friedman

Taco circulator runs non-stop

I'm dealing with a taco circulator pump that is running non stop.

I discovered it when the temperature in one zone was climbing way beyond the setting (set to 70, baseboards still hot when reading 75-77degrees0.

I've followed the suggestions on how to troubleshoot to no avail. I was to the point that every thermostat was completely disconnected from the zone valves, and the zone valve wiring was completely disconnected from the boiler/circulator. On 2015-12-17 by Ed

by (mod) - easy first diagnostic step:

Ed,

If the thermostat wires were disconnected at the circulator end and the circulator keeps running, I suspect a bad circulator relay or bad primary control.

I can constantly feel the heat coming from the floor even though my thermostat isn't calling for heat.

Hi, Dan,

I live in a condominium building (in Canada) and all suites have radiant floor heating. Except for the warmer months in the summer, it is much too warm in my suite so, I always have the patio door and/or window open and in turn, I have an unpleasant draft.

I can constantly feel the heat coming from the floor even though my thermostat isn't calling for heat. In fact, it is very rare that I've had to turn the heat on.

Approximately two-thirds of my suite is affected by this heating irregularity. In my suite, I have two thermostats and the area that I don't have a problem with is controlled by the other thermostat. I've had the one thermostat replaced, but the issue hasn't been resolved.

This same thermostat is the only control for the air conditioning, which works properly. Also, supposedly, the valves are all closed. There has been several plumbers/HVAC technicians through our suite (and all of the suites in our building) and they can't seem to fix the problem.

I have been told by the condo board that the issue isn't to do with the boilers, but I'm not sure what to believe. I would very much appreciate some advice as I'm at my wits' end! On 2015-09-17 by Karena

Reply by (mod) - of course the unwanted heat has to do with the "boilers" - or their controls

If heat is being delifered to your condominium through a radiant heated floor when you have your room thermostat set well below the current room temperature, then there is a problem with one of the two items I'll list below.

Start by checking out your thermostat.

• The thermostat itself (shorted wires or damaged or improper settings)
  
  See the diagnosis help at THERMOSTAT WON'T TURN OFF
• The boiler controls
  
  See the diagnostics at HEAT WON'T TURN OFF - topic home
  

I turned the thermostat off but we still get heat.

new hot water natural gas boiler, 4 zones , I have the thermostat off upstairs , but I continue to get heat, have a circulator running all the time, my installer is returning in a couple of day , my ? is my fuels bills are crazy , $370 every 3 weeks , could that be the reason On 2015-03-06 by john s

Reply by (mod) -

John,

Yes. Look for a misfired or shorted thermostat wiring problem.

If that's not the issue, there could be a check valve stuck "open" on the boiler.

See the diagnostics at HEAT WON'T TURN OFF - topic home

How can I troubleshoot my heating zone relay switch? One zone won't stop calling for heat.

I'm trying to troubleshoot my zone relay.

One zone keeps calling for heat with the thermostat off. I replaced my flow control valves thinking it was convection heat, and replaced the thermostat. The circulator seems to be shorting but I'm not sure how to narrow down the problem. On 2014-11-1 by matt -

Reply by (mod) -

Matt

I suspect that

The zone valve is latched open - leaving an end switch turning on the circulator

The zone valve motor has failed and is stuck open - leaving an end switch turning on the circulator

The thermostat wires are shorted

Start by disconnecting the thermostat wires at the zone valve.

If the valve has a manual open/close lever see if it can open and close the valve.

I think the zone relay switch may be bad: I can't get heat to turn off

I don't have electric zone valves only the Flow check valves which have been replaced. I have Honeywell zone relays connected to the circulators. I'm wondering if the zone relaying shorting but I'm not sure how to find out On 2014-11-19 by matt

Reply by (mod) -

Matt did you try just disconnecting the zone relay?

by Matt

I'm going to try that tomorrow. I think the previous owners put two pumps onto one zone relay. Not sure if that's possible, but there's a whole lot of wires and junction boxes in the boiler room so Itll take some time narrowing it down.

...

...

Continue reading at CIRCULATOR PUMP WON'T STOP RUNNING - topic home, or select a topic from the closely-related articles below, or see the complete ARTICLE INDEX.

Or see these

Recommended Articles

• CIRCULATOR PUMPS & RELAYS - home
• CIRCULATOR PUMP BASICS
• WHAT GOES WRONG WITH HEATING CIRCULATORS?
• CIRCULATOR DIAGNOSTICS
• CIRCULATOR PUMPS vs ZONE VALVES

Suggested citation for this web page

CIRCULATOR PUMP WON'T STOP RUNNING 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

Or use the SEARCH BOX found below to Ask a Question or Search InspectApedia

Ask a Question or Search InspectApedia

Try the search box just below, or if you prefer, post a question or comment in the Comments box below and we will respond promptly.

Note: appearance of your Comment below may be delayed: if your comment contains an image, photograph, web link, or text that looks to the software as if it might be a web link, your posting will appear after it has been approved by a moderator. Apologies for the delay.

Only one image can be added per comment but you can post as many comments, and therefore images, as you like.
You will not receive a notification when a response to your question has been posted.
Please bookmark this page to make it easy for you to check back for our response.

---

IF above you see "Comment Form is loading comments..." then COMMENT BOX - countable.ca / bawkbox.com IS NOT WORKING.

In any case you are welcome to send an email directly to us at InspectApedia.com at editor@inspectApedia.com

We'll reply to you directly. Please help us help you by noting, in your email, the URL of the InspectApedia page where you wanted to comment.

Citations & References

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

---

ADVERTISEMENT

---