FAQs on heating zone circulator pump won't start or seems stuck.

This article series explains how to diagnose & fix a heating zone circulator that will not run when it should.

Q&A on how to diagnose Stuck or "Dead" Heating Zone Circulators

These questions & answers about a hot water (hydronic) heating circulator pump that won't start or won't run were posted originally

at CIRCULATOR PUMP WON'T START - please be sure to check out the diagnosis and repair advice given there.

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

CIRCULATOR PUMP REPAIR FAQs - index

 

Our New zone circulator pump won't turn on

Just bought an apartment with radiant heat - there are two thermostats for the bedroom and main living room.

When we moved in, the heat from the living room wasn't working. The pump was apparently toast. It was changed out and the heat started working fine.

About 6 weeks later the heat isn't working again. No problems with the thermostat in the other room. Any ideas? On 2018-01-01 by JB

Moderator reply:

JB

Check the simple circulator diagnostics at CIRCULATOR OPERATION CHECKS

Then

see CIRCULATOR PUMPS & RELAYS

If the circulator is running the system may be air-bound

see AIR-BOUND HEATING SYSTEMS - diagnostics

If the circulator motor won't start at all

see the diagnosis and repair steps

at CIRCULATOR PUMP WON'T START

 

One zone circulator won't start, replaced thermostat

I have a internal coal 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 2020-01-18 by Derek Dethlefsen

by (mod) - check for shorted or broken thermostat wires

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.

by Derek

I did what you suggested and yes it works!

The heat is flowing non stop.

This eliminates the relay being bad. Thank you. I will run new TT wire. Do you recommend anything else?

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.

 

 

 

If the boiler or circulator stopped working, could it be a fuse?

When the pump of a boiler does not work or circulate, does it affect any of the consumer fuses by Nick

by (mod) - yes

Nick, by "consumer fuses" I think you mean to ask: if my heat isn't working could it be a fuse?

The answer is yes; check your fuse panel (or circuit breaker panel), find the circuit that powers your heating boiler, and reset the breaker or replace the fuse to see if that works.

If that doesn't help, start at the diagnostics:

HEAT WON'T TURN ON

 

No water comes out of my radiators and I have no heat

My boiler, Burnham p206w, comes on for about 10 seconds then stops. No heat from the radiators, and no water from the radiators when I try to bleed them. On 2016-11-13 by jeff

by (mod) - Is this a "circulator won't run" problem OR a boiler aquastat control or control sensor problem?

Jeff

That sounds like an aquastat control or control sensor problem, provided that the boiler reset button isn't tripped.

If your hot water heating system pipes and radiators are cold and the boiler itself has not turned on and run long enough to raise the boiler temperature up to somewhere under 200F and the pressure up to somewhere under 30 psi, then indeed when you try to bleed a radiator of air there may not be enough pressure in the system to push water OR air up and out through your air bleeder valves.

Try disconnecting your thermostat, then wiring the aquastat control (two) thermostat connectors together - that's exactly what the control sees (on the LOW VOLTAGE circuit) when the thermostat is calling for heat.

If the burner runs solidly then the problem could be a thermostat or thermostsat weire.

Bottom line: You can't successfully bleed radiators if the system is not up to operating temperature as the pressure will be too low.

If then when your boiler runs you still can't get air out of your system and the circulator isn't successfully pushing hot water through the zone,

see AIR BOUND HEAT SYSTEM REPAIR by PUMP 

 

Does a heating zone only get heat if the boiler itself is running?

Does the zone where the circulator pump only get heat if the main boiler is running ? On 2018-02-17 7 by JR

by (mod) - no

No Jr

As long as the water in the hydronic heating system is hot, when the room thermostat calls for heat the zone circulator runs, sending hot water through the zone, and the zone should get heat.

When water temperature in the boiler drops below the "CUT IN" temperature set on the boiler's control aquastat, that control will turn on the burner to re-heat the water.

In which direction should a circulator pump be sending hot water?

I have six Bell & Gossett motor/pumps on our boiler. There is a pump for each zone mounted above where all of the motor/pumps join into a manifold.

My question is which direction should the pump pump?

Toward the manifold (where all the pipes come together) or should the flow go opposite the manifold? On 2018-01-19 by Larry B.

by (mod) - six Bell & Gossett motor/pumps on a boiler.

Larry

Look at (and attach a photo of using the picture frame next to the Comment button) the location of your circulator pumps.

Usually circulator pumps are placed on the RETURN side of the boiler where their operation will be a little cooler and their life a little longer.

In that location the circulator is pumping FROM the house and INTO the boiler on its return side.

And vice versa: if a circulator is (rarely) on the boiler outlet side it will be piping away from the boiler and into the house.

Follow the pipes.

In case it's not obvious, hot water leaves the boiler from a pipe high on or on the top of the boiler; returning, cooler heating water returns to the boiler from a pipe that feeds into the boiler at a lower location, typically near the boiler bottom.

Circulator pump won't turn on

Hopefully an easy question- My boiler turns on and heats water that extends up the outbound pipe about three feet, but my Grundfos circulator pump isn't turning on and circulating the water.

The pump doesn't appear to be a fossilized relic due to fail, and it doesn't have a screw behind the nameplate to turn and ensure it isn't seized.

I actually purchased a replacement pump, but before I put it in, I'd like to check the system providing commands/power to the pump, and check any other possible reason the pump doesn't turn on.

( a secondary concern is that the new pump has three wire contacts (hot, neutral, ground) , and my old one just has two white wires running from the electrical control box to the pump, connected to the white and black pump wires with no obvious ground). On 2017-12-04 by Eric Bettinger

Reply by (mod) -

Eric,

Set the thermostat the controls the Zone heated by the circulator in question all the way up so that we're sure it's calling for heat.

That interns should cause the circulator relay to close which should send power to the circulator pump itself. At that point if the wires to the pump are not seeing 120 volts then the problem is most likely not the circulator but instead the circulator relay control.

If you follow the circulator wires back you will find them connecting to the circulator relay.

Circulator pump won't stop running

I have radiant floor heating with five zones and my heater never shuts off what could be the problem I was thinking it could be the circle pump on one of them On 2017-02-04 by Dori carter

One of my heating zone circulators is not running

Two zones baseboard hot water. Pipe hot coming out of one pump cold on the other. On 2016-12-14 by William Bertscha

Boiler heats up but circulator won't turn on

My furnace runs to temperature.

It will not circulate (pumpd does not turn on) then the furnace shuts off.

When the water cools down in the furnace , the furnace will restart and run fine until it hits temp again and shuts off. No circulation why? Pump bad? On 2016-12-09 by Chip

by (mod) -

Chip,

This indeed sounds like the boiler is reaching its cut-off temp without the circulator ever running. I

f the circulator pup ran, the boiler would be cooled by returning water and would run longer.

So check first for a bad circulator relay.

The boiler won't start when our second circulator pump / zone runs

We have a gas hot water heating system with a with two circulators, one for the basement heat where there is a separate thermostat (#2.

When basement thermostat (#2) is turned up, the circulator turns on, but the boiler does not light and radiators are cool.

Kept (#2) high; and turning upstairs thermostat (#1) up, boiler starts, downstairs circulator continued to run, basement radiators got warm.

Why doesn't (#2) turn on boiler? - On 2016-04-04 by Sheila

Reply by (mod) -

If the thermostat works and the circulator runs the system is calling for heat.

If the burner runs in response to one thermostat but not the other, and if both thermostats are able to turn on their respective circulators, I figure that the cold zone that's not lighting the boiler has no water circulating.

(It's water temp that turns on the boiler in most system wiring setups in most countries) .

I suspect that your zone is airbound (or the circulator impeller is broken).

Search InspectApedia for AIRBOUND HEATING SYSTEMS to read the details.

At what temperature should the boiler turn on the circulator pump?

I have a Hydrotherm Mod.# 2HWS gas boiler with a Taco 110 circulating pump

I notice the pump is not going on.

In the past I always noticed the shaft spinning.

At what Temp. of the boiler should the pump start its cycle. What could be checked ? Thank You John On 2015-10-31 6 by John

Reply by (mod) -

John

In the U.S. (if that's where you are) usually when you set the thermostat above room temp that turns on the circulator right away. If the circ doesn't run the common reasons are in the article above.

Pump tries to start but Won't Run but I can manually turn the impeller

My Taco series 110 circulator is not running at all. I can spin the impeller with my fingers.

It has oil in all three ports. It appears to be an always on pump as only on two wire runs to it from a switch.

When I turn it off then on again it turns a few rotations then stops. The pump is fairly old as is the boiler (oil fired residential 1200sq ft home in Baltimore). On 2014-11-23 by Tim Taco Circulator

Reply by (mod) -

Tim

It sounds as if the cicrculator pump is getting electrical power because you say the motor tries to start. So I suspect either a failed motor or a failed motor starting capacitor.

The Taco has a field replaceable motor - that may be what's needed.

But check first for a bad start/run capacitor serving the circulator motor.

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

Or see these

Recommended Articles

• CIRCULATOR PUMP BASICS
• WHAT GOES WRONG WITH HEATING CIRCULATORS?
• CIRCULATOR DIAGNOSTICS
  • BYPASS a BAD CIRCULATOR
  • CIRCULATOR COSTS
  • CIRCULATOR NOISES
  • CIRCULATOR PUMP DIAGNOSTIC CHECKS
  • CIRCULATOR PUMP LEAKS
  • CIRCULATOR PUMP MANUALS
  • CIRCULATOR PUMP RELAY MANUALS
  • CIRCULATOR PUMP MOTOR or BEARING FAILURE
  • CIRCULATOR PUMP MOUNT LOCATIONS
  • CIRCULATOR PUMP MOUNT POSITION
  • CIRCULATOR PUMP RELAYS & OTHER CONTROLS
• CIRCULATOR PUMPS vs ZONE VALVES

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INDEX to RELATED ARTICLES: ARTICLE INDEX to HEATING BOILERS

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