Hot water heating circulators or circulator pumps & relay FAQs:

Questions & answers about how to install, troubleshoot, & repair hydronic heating system (hot water boiler) circulator pumps and circulator relays or controls.

This article series answers most questions about Heating System Boiler Controls on central heating systems to aid in troubleshooting, inspection, diagnosis, and repairs.

Heating Circulator Pump Diagnosis & Repair FAQs

These questions and answers about troubleshooting hot water (hydronic) heating system circulator pumps were posted originally at CIRCULATOR PUMPS & RELAYS - be sure to see the advice given there.

Heating circulator pumps or "zone circulators" are used to force hot water from the heating boiler through radianting devices such as hot water baseboards or radiators. The circulator is switched on as needed or in some designs may be wired to run continuously.

Our photo at left of a red B&G heating circulator pump shows equipment more than twenty years old and still spinning along nicely.

[Click to enlarge any image]

On 2020-01-21 by (mod) - successful circulator repair report

Thank you SO much for the follow-up, Derek, the conversation will surely help other readers.

Other than replacing the TT wires and making sure connections are good I'd quit there.

IF there are more problems we can look elsewhere like at a control board or a low voltage transformer.

So glad this worked for you.

On 2020-01-20 by Derek

I did what you suggested and yes it works!
The is flowing non stop.
This eliminates the relay being bad. Thank you. I will run new TT wire. Do you recommend anything else?

On 2020-01-18 by (mod) -

Derek

It sounds as if you've done one of the key first-tests, jumpering the thermostat wires together at the thermostat end.

But a bad TT wire enroute or a loose connection at the other end can also give the trouble you describe.

Let's take the thermostat out entirely by going to the other end, at the furnace itself, and find the thermostat terminals and jumper them together.

If the circulator runs then the problem is in the thermostat or its wiring or wire connections.

On 2020-01-18 by Derek Dethlefsen

I have a internal coul furnace with 3 zones. Two zones are used. The upstairs zone works fine. The downstairs zone seems to work intermittently. I have replaced the thermostat and the problem continues.

The heat does not drop below 60(F) but it also does not go above 65(F). I have taken the thermostat out of the equation and connects the two wires together. Think the heat would run non stop. But the zone turns on and off still not getting the room to a warmer temp. Any insight oncwhg this would be ?
Thank you

On 2019-11-26 by (mod) -

connection needs to be cleaned and remade and source of water or moisture corrected as well

On 2019-11-26 by Herb

Wires corroded at the connection

On 2019-11-11 by Anonymous

I Have hot water circulator system 4 zones but one circulate a pump and always banging

On 2019-10-12 by (mod) -

Al,

There are woodstove systems designed to provide domestic hot water but with apology I'm way too scared to recommend a do it yourself version; a mis-routed pipe or mis-selected temperature/pressure relief valve and you can blow the whole shebang, woodstove, water heater, house, and people in it to smithereens.

So I'd prefer to see what heater manufacturers and their engineers offer.

On 2019-10-12 by al halliday

need a system to get hot water from wood stove ? I have 5/8 copper which I am coiling around outside 6 inch stove pipe and covering with 8 inch stove pipe . I have house cold water line near by. Going to heat 4 baseboard heaters with hot water .

I have heat pumps in house and am using wood stove heat for secondary heat. Can I use old pressure tank [bubble inside tank leaks installed new tank] ? Was going to use a thermostat regulator circulating pump temperature controller . Would 1 pump do it ?Thanks

On 2018-12-21 by David Moran

I have a boiler with 1 taco circulating pump to two zones each zone has its own thermostat. One zone heats great the other zone is cold. I purged all the air out and the baseboard got hot. Came back next day second zone cold again first zone great heat. I purged the air out again got hot again. Came back next day same thing second zone cold. What do you think is going on?

On 2018-12-13 by Alex

Weird one... the thermostat turns on at the desired time, it wakes up the boiler and the circulator clicks on (I see the zone light on and hear the circulator working) BUT no heat is going to the baseboards! Pipes in and out are warm but not hot, circulator is hot. Other zones working fine. What could be going on? Heating technician bleed the system and no air block. Any thoughts?

On 2018-11-10 by (mod) -

On 2018-10-12 by (mod) - can I replace two circulator pumps with a single unit?

Gary you can usually replace one circulator pump with a different model; if you want to combine two zones onto one circulator you'll need to change some piping and add a zone valve.


On 2018-10-12 by Gary

I have a boiler system with two circulating pumps. One is a 106189 which is leaking. It was replaced about 20 years ago. The other is a 102210 that is extremely noisy and has been there forever, it vibrates the whole system. Can I replace both with the 106189?

On 2018-10-12 by (mod) - can I replace two circulator pumps with a single unit?

Gary you can usually replace one circulator pump with a different model; if you want to combine two zones onto one circulator you'll need to change some piping and add a zone valve.

On 2018-10-12 by Gary

I have a boiler system with two circulating pumps. One is a 106189 which is leaking. It was replaced about 20 years ago. The other is a 102210 that is extremely noisy and has been there forever, it vibrates the whole system. Can I replace both with the 106189?

On 2018-10-10 by (mod) - you could stick with a single circulator

SoD

Most-likely you could stick with a single circulator; if you want to control the second floor as a second zone you'll need to add a second floor thermostat that controls a separate zone valve that opens to send hot water to the second floor baseboards or radiators.

On 2018-10-10 by Son of a Diddly

I have a single zone, single circulator, single floor boiler system. If I wanted to tap into that and bring heat to the second floor, would I need a second circulator for the second floor? Otherwise, why would the flow want to go up there? Thanks.

On 2018-05-29 by Angel

I recently moved into a newly built apartment that has a Taco 003-B4 recirculator attached to the water heater.

It is plugged into a timer that appears to be set so that the pump won’t run during the late night hours.
The problem I have is that I work a schedule that causes me to be up and active at home during these “off” hours and I get no hot water to the entire house during this time.

And during the “on” hours I get water that is often hot only for a short time then goes warm. Is this the way this pump is supposed to work?

I have never seen one of these before moving here so I have no experience with how they work.

What I gathered was it was a sort of on demand type of thing to keep the hot water flowing for quick availability as needed.
I’d like to just turn it off completely but am afraid I will be without hot water as it seems to not let any hot water through when it is turned off.

On 2018-02-08 by (mod) - only one zone turns on the circulating pump

It could be

- a bad end switch in the zone valve

- a bad wire between zone valve and circulator relay or zone controller

- a bad circulator relay

- a bad circulator pump

- or if a careful check shows the pump is running, it could be an airbound zone

On 2018-02-08 by Calvin

I have a 2 zone heating system, both zone valves open when it's calling for them to but only one zone will turn the circulating pump on. Could it be anything other than a wiring issue??

On 2018-02-01 by (mod) -

Sure Paul, we have a series of procedures to remove air from an air-bound heating system. Use the search box just above to find AIR-BOUND HEATING SYSTEMS at https://inspectapedia.com/heat/Air_Bound_Heating_System.php

On 2018-01-28 15:38:27.420585 by Paul DELANEY

We replaced a small stretch of hot water baseboard there are no bleeders in basement. When we put the temp back on and pump came back on the system basement was air locked. No water through the new piping and only a small section got warm any suggestions

On 2018-01-14 00:44:21.190936 by (mod) -

Brian

I'm not sure what a re-circulator is but I 'm guessing you refer to a circulator system using a hot water piping loop and a circulator pump to keep the water hot throughout the piping system so that tenants get instant hot water. That pump is typically independent from the aquastat that controls the boiler or water heater.

On 2018-01-13 16:55:42.859141 by Brian Reilly

Anyone know if a re-ciculator pump on domestic hot water in a multi-family complex needs to have an aquastat controlling it or can it be wired to circulate continually?

On 2018-01-06 05:36:22.701711 by (mod) -

Yes patty. The relay may hzve power but may not open or close in response to the control board signals to do so.

On 2018-01-05 23:28:13.753741 by Patty

Can a relay be bad and still have power goi g to it

On 2018-01-04 00:51:29.502856 by (mod) -

Bill,

Probably, but we cannot really know as we don't know a thing about the controls on your system

On 2018-01-04 00:49:53.476786 by (mod) -

Tom,

The circulator arrows must point in the direction of intended hot water flow.

On 2018-01-03 19:33:28.543930 by Bill

I have a 2 boiler system for 12 apartments in 3 separate buildings. Should both circulators be running?

On 2017-12-31 by Tom Should both circulates arrow be pointed up

Should both circulates arrow be pointed up

On 2017-12-03 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 at https://inspectapedia.com/heat/Aquastat_Settings.php for details

On 2017-12-03 by Rick W.

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 2017-11-26 by (mod) - Very little heat coming into house

Anon

Use the search box just above yo search for

NO HEAT FROM BOILER
to find our diagnostic suggestions

On 2017-11-26 by Anonymous

Very little heat coming into house

On 2017-11-18 02:18:03.243509 by (mod) -

Generally not, Andy.

On 2017-11-17 23:46:47.491741 by Andy

Is there a reset button on circulatir pump

On 2017-11-08 01:30:59.858427 by Anonymous

@Mike,
Or fire up

On 2017-11-08 01:30:30.220622 by Mike

If a circulator doesn’t work will that make the burner not turn on

On 2017-10-31 17:33:24.625711 by Tom

I have three zones. One not pushing heat. Pump is running

On 2017-10-14 17:23:36.770523 by (mod) -

If the AC blows air but the air isn't cold, I don't understand how to relate that to a zone circulator - something I associate with forced hot water heating.

I think you're saying that during air conditioning the heating system is improperly heating a hot-water-to-air coil in the duct system.

That's certainly possible: a boiler can circulate water by natural convection even if the circulator pump itself is off, particularly if check valve(s) on the system are not working.

See CHECK VALVES, HEATING SYSTEM at https://inspectapedia.com/heat/Check_Valves_Heat.php and you can see typical check valves on hot water heating systems - usually located on the heat-out lines from the boiler, above it.

On 2017-10-13 03:03:29.032116 by Steve

“Newly installed Central air zone suddenly doesn’t blow cold air!” (Heating System shares AC DUCTING AND BLOWER, using a hot water coil in the airs path Home is 15 yrs new, buikt beyond heating and cooling specs, )..

Installer said that Faulty check valve above / contained within? that zones circulator is “leaking, hot water to the heating coils, warming the airti 77-80 when the ac set to 73. Temp fix was to close the flow valve just beyond the circulator. Installer vague on what and where the check valve is? I don’t see a physical valve in/ on the line, just the circulator and the on-off, quarter turn valve with the flat handle above it. What is the realistic cost of draining system, check valve replacement, refilling system? Any point of refilling zone with an anti corrosive and antifreeze type liquid? Thanks!

On 2017-05-01 17:05:14.311897 by Beth Brown

Would a faulty circulator pump that was not shutting off cause excess use of oil and electricity?

On 2017-03-20 18:53:33.560655 by (mod) -

It sounds as if your pump stopped pumping, but we don't know if it's because a switch or control has failed, the pump is damaged, or the well is low or out of water. That's what an on-site plumber will check, probably in that order.

If you search InspectApedia using the box just above for LOST WATER PRESSURE or NO WATER PRESSURE you'll see a sequence of diagnostic steps that should be helpufl

On 2017-03-20 13:38:42.155010 by Cheryl

One morning after a shower n a load of laundry my water was trickling out...hot n cold until the water ran out. I checked the pressure gauge. I flip it and it won't hold any pressure. Gauge doesn't move.
Does this mean I need a new pressure box? If so is there trouble shooting or simply diy tips you might have?

On 2017-03-16 23:52:04.789826 by (mod) -

It sounds as if a safety control is turning off your heating boiler.
It's time to call for repair service.

The fact that you don't get heat upstairs may be due to any of several common problems:
(Search InspectApedia.com for the capitalized phrases to read more detail)
such as
AIR BOUND HEATING SYSTEM PIPING
or
CIRCULATOR PUMP not working if upstairs is heated by a separate circulator and circulator relay control and thermostat
or
ZONE VALVE not working

On 2017-03-15 22:41:51.047185 by Darlene

My oil hot water furnace works then shuts off..can run for hours then not restart...when it does work it heats up the main floor but not the upstairs..replaced the pressure valve and new thermostat..

I hv lots of hot water but no heat..the pump is hot but the pipes above it are warm for about a foot but then turn cold.. could the pump not be working right..would this cause the furnace not to work at all

On 2017-03-03 23:54:26.581036 by (mod) -

Typically I see leaks at the circulator mounting flanges - less often within the pump itself. The taco has a replacable pump cartridge. Look carefully to see if you can spot the leak, but do not pick at rust and corrosion or it may get quickly worse. It's time to call for a replacement by your service tech.

On 2017-03-03 17:05:01.503831 by Jack

Hi,

I have a weil mclain ii boiler and for the last day and a half the pipe connecting the taco cartridge circulator that points to the ground has been dripping water.

The dip isn't a steady flow, it stops at times but than continues. I'm not sure if that's a issue, I've never seen my boile drip water and that why is concerns me.

The valv connecting the pipe and cartridge circulator is extremely rusted and I'm not sure if that is the issue. I also can't get someone to look at it for a few days, please let me know if i have big issue on my hands. Thank you

On 2017-01-14 18:39:53.656444 by (mod) -

Dom

I don't assume there's no air in the system since air blocks can be sneaky, subtle - e.g. blocking a horizontal run that just doesn't allow air to get up to the nearest air bleeder.
\
Other issues: a blockage in the piping, a zone valve that you think is open when it's not, or a circulator whose motor runs but whose impeller is damaged or broken completely.

Feel the pipes. Follow the heat - or the cold. That usually points to the trouble spot.

On 2017-01-14 14:48:18.166922 by Dom

Hi I have a forced hot water baseboard syst. One of my zones is not getting heat. the circulator seems to be working because its humming (problem?) there is no air in the system.
what could it be?

On 2017-01-14 by (mod) - don't assume there's no air in the system s

Dom

I don't assume there's no air in the system since air blocks can be sneaky, subtle - e.g. blocking a horizontal run that just doesn't allow air to get up to the nearest air bleeder.
\
Other issues: a blockage in the piping, a zone valve that you think is open when it's not, or a circulator whose motor runs but whose impeller is damaged or broken completely.

Feel the pipes. Follow the heat - or the cold. That usually points to the trouble spot.

On 2017-01-14 14:48:18.166922 by Dom

Hi I have a forced hot water baseboard syst. One of my zones is not getting heat. the circulator seems to be working because its humming (problem?) there is no air in the system.
what could it be?

...

...

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

If you are not getting any heat at all out of a cold baseboard or radiator, see COLD HEATING BASEBOARD / RADIATOR REPAIR

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

• AIR BLEEDER VALVES
• AIR SCOOPS PURGERS SEPARATORS
• AIR-BOUND HEATING SYSTEMS
• ANTIFREEZE for BOILERS
• BOILER LEAKS CORROSION STAINS
• BOILERS, HEATING - home
• BOILER CONTROLS & SWITCHES
• CHECK VALVES, HEATING SYSTEM
• CIRCULATOR PUMPS & RELAYS
  • BELL & GOSSETT B&G EQUIPMENT MANUALS & CONTACT
  • CIRCULATOR PUMP BASICS
  • WHAT GOES WRONG WITH HEATING CIRCULATORS?
  • 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 & OTHER CONTROLS
  • 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 REPAIR FAQs-2 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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