Heating zone circulator pump repair procedures for noises:

This article describes how to diagnose & fix noisy circulator pumps on hot water or hydronic heating systems.

We distinguish among buzzing relays that control the circulator, vibrating electric motors, shrieking circulator bearings, and circulator pump noises. Understanding the noise made by a heating zone circulator pump and whether or not the noise is normal can help us diagnose and fix equipment without wasting a lot of time chasing the wrong problem.

Circulator Pump Noise Repair Guide

Reader Questions: Heating Zone Circulator Pump Noises, heating system noises, or noises when heat is turned off

Humming at the boiler

(Oct 13, 2012) zena123 said:

Help, please ! Central heating system is turned off. However, an unpleasant hum comes from central htg. boiler. When elec. is turned off at consumer unit, humming ceases. Any ideas gratefully received. Tx.

Bang noises at the boiler or expansion tank

(Oct 29, 2012) Jim said:

When circulator pump turns off, there are 4 pairs of bang-bang, which seem loudest at expansion tank.

Draining expansion did not change. Heating and other operation is OK. I suspect, and will replace, the coupler between electric motor and impeller.

Also see BANGING BOOMING NOISE DIAGNOSIS & CURE - home

Trickling water sounds in the heating system

(Jan 10, 2013) Anonymous said:

I hear trickling water on one of my baseboard on my top floor everytime the heat starts to work. It goes away after awhile. I bleed that baseboard and it still trickles.

Squeeking Noise at the heating boiler

(Mar 13, 2014) Steveo said:

I have a squeeking noise that only happens early in the day and then again at night...it is coming from the water-out pipes (hot) and the sound "goes away"...I'm really confused. The pump's coupling was changed this season and it was oiled...any ideas??

Reply:

Zena:

Your heating service technician will probably check for a humming relay, control, electric motor, or burner motor. I'd turn off the system while waiting, in case it's an electric motor that is jammed or stuck.

Jim:

I'm not sure what's going on but I'd start with the most dangerous: checking that the BANG! is not coming from the oil burner itself.

See PUFFBACKS, OIL BURNER to rule out that hazard.

Anon: trickling water means there's probably air in the hot water heating system piping. See our air-bound heating system diagnosis and repair articles in the links below.

SteveO

I'd try to track the noise to location as well as by whether or not equipment is running or not. It could be an expansion/contraction of piping moving through a tight opening as temperatures change.

Louder sqeaks and shrieks are often a failed or failing motor or pump bearing.

Also see BANGING BOOMING NOISE DIAGNOSIS & CURE - home

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Reader Q&A - also see RECOMMENDED ARTICLES & FAQs

On 2020-06-29 - by (mod) - using a degasser or air eliminator in a solar heating system

Thank you for the added detail. Perhaps we want to make changes to eliminate rust clogging in general combined with a system cleanout.

Frankly I'm surprised to find actual "rust" (iron oxide debris or flakes) in a solar heating system that's usually using plastic or copper tubing. Have you no idea of the source of the debris?

On 2020-06-29 by René

Here the schema of the future place for the degasser, wherein there is no possibility of having air entrapped in the pipe.

I'll will have a look at the links you provided. Thanks for it.

On 2020-06-29 by René

I have two brands of degassers : Flamco and AWB. They both do the job properly.

On 2020-06-29 by René

thanks for your reply.

What changed in my system? No initial action from my side. Don't fix things which are not broken. I think the expansion tank slowly corrodes from inside since it contains hot glycol, air, and probably some condensation water.

The iron oxide travels then through the installation and settles in the roof collector. The "cold" ascending pipes had an external diametre of 12mm (0.5") and the "warm" descending ones, 8mm (0.3").

The last ones were almost clogged by rust.

I replaced them by 10mm pipes (0.4") and glycol circulates now freely.

I still have to put the pomp on maximum pressure whereas the intermediate stand was originally sufficient.

Here the original installation (Schema-1)

On 2020-06-28 - by (mod) - list of types of air removal methods & applications on heating systems

Thank you for the interesting solar boiler air removal question, René

We have talked about air eliminators or air removal devices in several topics including

AIR BLEEDER VALVES - or "Degassers" both manual and automatic float-type - on hot water heating systems -

AIR ELIMINATORS for POTABLE WATER SUPPLIES

AIR SCOOPS SEPARATORS PURGERS on heating boilers

OIL BURNER FUEL UNIT AIR BLEED PROCEDURE

and even OIL LINE DE-AERATORS Tigerloop™

but I haven't focused specifically on air problems in solar heated equipment or as you put it solar boilers.

The underlying causes and cures are similar across these devices: heat converts dissolved air into bubbles that cause trouble in the system, even leaving it airbound.

One diagnostic question occurs to me: what changed in your system that we might associate with the onsite of the air problem?

Beyond that, Rather than embarrass myself by speculating at the optimum placement of the de-gasser on a solar boiler, I'd like to have the brand and model of the degassing device you're using. I think that the manufacturer probably has a publication that would help us out.

Or for example, you could contact

Spirotech Spirotech BV
Postbus 207
5700 AE Helmond
Netherlands
www.spirotech.com/contact-us/

On 2020-06-28 - by (mod) - need a de-gasser or air removal device for self-installed solar boiler

Rene

Try using the "add image" button - you can post one image per comment.

On 2020-06-28 by René

Schema-2, now [shown above]

On 2020-06-28 by René

Hi,
Since years, my self-installed solar boiler (see Schema-1) worked without any issue. Until this year, when the cooling fluid (100% glycol) started boiling in the collector on sunny days and the pomp was not powerfull enough to flush (and cool) the pipes.

Flushing and chemically cleaning the whole installation, together with the installation of a more powerfull pomp helped. However, after 1/4 hour working, gas bubbles start accumulating in the pipes, making noises in the pomp and pressure drop. It also appears that big bubbles penetrate the expansion tank.

I suppose the bubbles are created by the degasser (3) which is located at a place higher than the expansion tank and boiler serpentine, and thus almost constantly filled with air. Experience has proven that installing a degasser at the highest point of the installation, on the roof, results in a huge amount of bubbles.

My question: Would moving the degasser to a point LOWER than the liquid level in the expansion tank and boiler serpentine, just after the pomp, be efficient for capturing the bubbles ? See Schema-2. This way, the degasser would capture the bubbles immediately after the pomp, without letting air penetrate the installation.
Thanks for your answers/comments/suggestions.
René

On 2019-10-04 - by (mod) -

circulation pump not turning off

Anon

- is the thermostat calling for heat?

In the ARTICLE INDEX see HEAT WON'T TURN OFF

On 2019-09-30 by Anonymous

circulation pump not turning off

On 2018-02-11 - by (mod) -

circulator pump bearing failure can be very noisy, humming, whining, screeching, vibrating, whistling, buzzing, rattling

Darren

In the building from which I'm answering your query, in Two Harbors MN, the heating system, installed more than 30 years ago, uses five different circulators. The circulator pumps dated to the construction of the building in the 1960's.

Over that time the B&G circulators gave stellar performance, but no circulator pump lasts forever.

Proper mounting and lubrication extend the circulator life, but ultimately the circulators wear out, showing failure in one of these most-common modes:

1. The flange mounting gaskets leak onto the pump until it's ruined - this would have been an inexpensive repair if caught in time

2. the motor bearings or pump impeller bearings fail, becoming noisy - new pump time

3. the pump impeller leaks - new impeller assembly time

So yes the bearings could be failing.

The last of the original B&G circulators at our building was replaced last month after decades of service.

On 2018-02-11 by Darren

Today I woke up to what I thought was my neighbors generator running.

Then I realized it was coming from my oil burner which is two flights of steps down in basement. My Peerless burner has a B+G circulator pump that is running but extremely loud humming.

Enough that some of my radiators are vibrating from the noise. Could it be bearings are going?
What would cause it to be so loud?

On 2018-02-08 by (mod) -

Glad to assist. Your questions and comments help us see where more research or information are needed.

On 2018-02-08 by Ed

Thanks a lot and I'm glad that this site is still active. I learned a lot by investigating my issue and will keep it bookmarked for future use. I will check out the other people's money post.

On 2018-02-08 by (mod) - look at noise from the boiler or its circulator with questions in this order:

I would look at noise from the boiler or its circulator with questions in this order:

1. Is there a failing pump - like a bad bearing - risking leaks and loss of heat?

2. Is there inadequate pipe mounting or a need for sound-isolating pipe securing fittings (pipes across a ceiling turn the floor above into a loudspeaker)

3. Is there some other abnormal operation or unsafe condition that we're led to by the noise?

If none of those, you can indeed defer moving the circulator from one side to the other of the boiler, not to mention how mad we'll both be if you shell out $1500. only to find it makes no difference in the noise, and that the problem is elsewhere.

I call this the OTHER PEOPLE'S MONEY problem and wax nauseous on that gripe over at https://inspectapedia.com/home_inspection/Other_Peoples_Money.php

Daniel

On 2018-02-07 by Ed

Thanks a lot for your response. I wasn't sure that anyone was stil monitoring this site.

I don't think that he knows the cause of the noise, but he feels that any noise should be dampened by pumping the water through the boiler first before it is circulated through the pipes to the rest of the house. I tend to doubt that. Regardless, we won't find out because I'm not giving him $1134 plus the $270 I have already paid for him to maybe fix the problem.

Even if the pump isn't located on the supply side, it has worked for over 7 years this way. Plus, the rattling noise does not happen when heat is called for again after reaching the thermostat set temperature. I

'm going to make sure that all the places that the pipes are hung have some isolation between the pipes and the hangers, which are steel chains in some cases. Wish me luck.

On 2018-01-31 by (mod) -

Ed

I agree with your service technician about the proper location for the circulator pump. B

ut I would sure be grateful if you could ask the electrician to explain why locating the pump on the supply-side would be cause of the noises that you have described.

On 2018-01-29 by Ed

When our circulating hot water heating system with radiators turns on after being off for several hours we get a rattling sound that we can hear through the radiators.

Once the system is warm and heat is called for again, the rattling is much less if at all. A technician replaced the Grundfuss pump with a Taco pump, but the noise persists.

He went back to the Grundfuss. Now he wants to move the pump from the supply line to the return line (for over $1100) he says that is how it should have been installed when the system was replaced 7 years ago. I am beginning to think that we are being taken for a ride and the rattling is just the pipes expanding from the hot water. Thoughts?

On 2016-02-29 by (mod) - replacing my Taco 007-F5 Circulator

Re-Posting:

2016/02/28 Bill said:

Sharing my recent experience in replacing my Taco 007-F5 Circulator. Perhaps it will help some fellow DIY’ers.
Existing Circulator started making noise. Decided to replace the entire unit.

Reasons:

(1) while possible to replace just the cartridge cost is ~ 80% of the entire unit,

(2) current install used the flat red ‘rubber’ flange gaskets and they had hardened up and

(3) there was some noticeable rust around the flanges. So for less than $100 had new Circulator + new Bolt Set with the flat red flange gaskets.

Note: the new Taco’s come with the ‘square’ rings, not the rubber gasket. And they do not come with new bolts. New pump also has square ring grooves in the flange face to accept the rings.

In researching found out that Taco changed to square ring due to fact that the red gaskets can ‘take a permanent set, and with the materials expanding and contracting, Taco decided to change over to the o-ring type…’ Square rings it is.
Disassembly straight forward and not covered here.

Clean up of boiler / pipe flange faces was accomplished with scrapper, wire brush and finally, do to some heaver scale, with an electric palm sander with 100 grit.

Cleaned and until nice and shiny but still had some very minor pits, and right on the surface where the square rings would seat. Stuffed small rag into pipes during cleaning to keep out debris. Don’t forget to take out!

Found lot of comments about using gasket sealant and how much to torque the bolts. Here is what I did.

I decided on Permatex non-hardening form a gasket due to a concern about the small pitting on the boiler flanges.

Used “a small dab will do ya’ on the side that seats into the Circulator, spun it around a turn or two to evenly spread. Then set up for install but putting one side’s flange bolts pushed thru the boiler flanges.

Idea is that will put a thin film of sealant on the square rings and need to get installed quickly before it sets, so with one side bolts sticking thru, can slide on the Circulator, stick thru the other bolts and it will stay put while you put on nuts , align and tighten.

Note about the nuts. These are against the Circulator flange that is a ‘slot’ not hole.

So I used washers under the nut (not bolt) because I believe it will help spread the clamping force better. Or perhaps I am just set in my ways and bolts need washers under.

For torqueing the bolts, did not use a set value. Instead I heeded the advice I found that aligned with my own experience that says in part:

‘one of the main design features of the thick square section ring gasket is vibration isolation, but if you crank it down until the flanges almost touch you lose that function plus you distort the gasket and it is more likely to leak’.

I tightened down the boiler side flange first since its flange is hard mounted so to speak. I tightened the left side nut a little, then the right side a little, back to the left side, etc. I made sure the gap between the 2 flange faces was even and had a visible gap.

I ended up with about 2 ½ threads showing and I measured the gap at ~ 0.056” Then did same on the pipe side.

Note: since it is more of a “snugged up” then torqued down, I did use Blue Threadlocker.
Filled it back up, fired it up and just perfect. No leaks.

On 2016-02-03 by owen mcdevitt - when pump starts tapping noise in boiler or pump

noise when pump starts tapping noise in boiler or pump which is mounted next to boiler on return piping just started making noise this winter suspect it is the pump have in-closed single loop system radiators don't seem to get real hot like before????

On 2015-12-07 by (mod) -

What kind of noise:

Gurgling - air in the piping system

Buzzing - a bad control or relay

Humming, shrieking, grinding - a failing pump motor

On 2015-12-07 by Jerry Warren

Noisy pump

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Continue reading at CIRCULATOR OPERATION CHECKS or select a topic from the closely-related articles below, or see the complete ARTICLE INDEX.

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• HEATING SYSTEM NOISE DIAGNOSIS

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

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