Leaks at Heating Circulator Pumps
Where do leaks occur at zone circulators, why we care, how to fix them? When is emergency repair needed?
CIRCULATOR PUMP LEAKS - CONTENTS: Leaks at heating boiler circulator pumps - where and why they occur. Circulator Pumps: Hot Water Heating System Circulator Troubleshooting & Repair Guide. Circulator pump relay switches & controls on heating systems: Troubleshooting & Repair. Video of a rapid leak at a circulator pump.
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Circulator pump assembly leaks on hot water heating systems:
Here we explain how to find and fix the common points of leakage found at heating system circulator pump assemblies.
This article series discusses Circulator Pumps: how to find, inspect, diagnose, and repair problems with Hot Water Heating System Circulator Pumps
or circulator pump relay switches and controls. This article series answers most questions about Heating System Boiler Controls on central heating systems to aid in troubleshooting, inspection, diagnosis, and repairs.
Small Leaks at a Circulator Pump - Mounting Flange Gasket Failure
A common spot where we find leaks on hot water heating systems (hydronic heating) is at the flanges mounting the circulator pump to the heating water distribution piping. Notice the white salt deposits on the circulator pump in our photo?
Note that the white deposits can be followed upwards to the upper circulator pump mounting flange bolt. More stains suggest leaks are active at the lower flange too.
[Click to enlarge any image]
Perhaps this is due to a failure to properly tighten the mounting bolts, or possibly because the flanges are supporting quite a bit of weight when larger (B&G type) circulator pumps are installed rather than the smaller (Taco type) pumps.
Because the heating distribution piping is normally hot you usually won't see water on the floor very often when there is a leak at the circulator pump mounting flange - only in extreme cases.
But if the circulator pump is leaking at the flange mounts, after even just a week or so of leakage you will see a build-up of mineral salts and corrosion at the flanges.
In our opinion a good time to fix this leak is at annual service at the end of the heating season, when it will be less inconvenient to shut down, cool off, and possibly drain the heating distribution piping.
At below left is a little leak at the bottom circulator pump mounting flange [Click to enlarge any image] where you can see rust stains that do not appear on the sister circulators shown in the picture.
At below right you can see things getting a bit uglier on a different circulator.
Below my ruler points to severe corrosion at the copper-to-cast-iron circulator pump flange.
Why do circulator pump leaks go un-repaired?
Well the little leak at the red circulator at above left may not even be dripping onto the floor. Those hot heating pipes may be evaporating the small quantity of boiler water that leaks and runs down the pipe.
So nobody cares, right?
If you allow a leak at a heating system circulator pump to continue for too long, the plumbing and pump parts may be so damaged that the repair is both more difficult and more costly.
In the photo (left) we show a leak that continued at the Taco™ circulator pump mounting flange for long enough that the plumbing parts are badly corroded.
Instead of a "bolt-on" repair, additional plumbing work, and thus additional repair costs will be involved.
While the leak above appears to be due to poor sealing at pipe threads connecting to the circulator flange, most leaks occur at the circulator flange gasket itself.
The replacement gasket shown above is not exactly expensive - probably less than a dollar. So why do circulator pump leaks weep for attention?
I suspect it's because we notice these leaks during the heating season. It's cold outside.
Nobody wants to go to the trouble to shut down the heat and maybe have to drain the system just to install this little gasket.
If you do need plumbing repairs when replacing a circulator pump or pump flange assembly, this is a great time to ask your plumber or heating service technician to also install a service valve right at the circulator pump - if one is not already there. Having these isolation valves in place makes circulator repairs a breeze - well a comparative breeze.
Our next two photos (below) show a service valve added at a circulator pump (below left) - with a leak needing repair, and a leaking circulator pump at the mounting flange ( below right).
A working shutoff valve on the heating distribution piping at the circulator pump can reduce the repair time, trouble, and cost the next time that circulator pump assembly repairs are needed.
Also, if flow balancing valves are not already installed on the system, a valve at the circulator pump can permit balancing of hot water flow among multiple heating zones when all of the zones are calling for heat at once.
Our photo (above left) shows a valve at the inlet to a circulator pump on a hot water heating system. As the valve is leaking, this control valve will speed the repair process.
Video Example of Rapid Circulator Pump Leak
Our photo above, taken by our field inspector K.K. sports a blue circle around a rapidly-leaking older style B&G circulator pump on a Northern Minnesota home. [Click to enlarge any image]
Click on the circulator pump image below to view K.K.'s video recording (1MB file, MP4 format) of what we consider a serious circulator pump leak.
What should you do about a rapid circulator pump leak like the one in the photo and video above?
Our on-the-scene field consultant K.K. took the following steps:
Determine that the boiler leak rate is significant - rapid dripping that fills a coffee can in a half hour is in our opinion a fast leak. A rapid heating boiler leak needs prompt repair by a trained heating service technician.
We needed to decide if we could leave heat-on and we needed to decide if we needed to make an immediate emergency-heat-repair call (more expensive than normal service) or if we could wait until morning of the following day.
Decide if it is safe and desirable to leave the heating system in operation.
We discussed the state of repair of the heating system, confirming that the service company had just recently installed a new automatic water feed valve. An automatic water feed valve will feed make-up water into the system if the system pressure falls below 12 psi - a condition that occurs normally when the system is cold (that is, heat has been off for a time) or at any time if so much water leaks out of the boiler that its internal pressure drops below that setting.
We decided that in this case it was safe to leave the boiler turned-on, a desirable choice considering that the home, located in Northern Minnesota, was facing high winds and low temperatures, risking both uncomfortable occupants and damage from freezing pipes if heat were turned off and if we could not obtain very quick repair service.
Watch out: Most residential hydronic (hot water) heating boilers in North America don't have an automatic low-water-cutoff valve (LWCO) though that control can be added, and it's found on virtually all steam boilers.
A heating boiler that is not shut off when it has lost its water supply is unsafe, risking a BLEVE EXPLOSION or permanent damage to the boiler. So if we thought that the boiler water level would not be maintained, or if we saw steam coming out of the boiler's temperature/pressure relief valve, we would have had to shut down the heating boiler immediately - by turning off its power switch.
Avoid water damage to the building. While this boiler leak was in a garage with a concrete floor and a working floor drain, our on-site field inspector decided to place a bucket or container to catch leaking water - see photo and video above
Call the heating service company for repair. A call to the local heating service company the following morning led to a prompt service call. The heating service technician agreed that the circulator pump was leaking - most-likely around the pump bearing, a leak that is not field-repairable. He replaced the circulator pump with a new one.
Circulator Pump Bearing and Circulator motor failures on hot water heating system pumps and what causes them: circulator pump mounting and support errors
On some circulator pump models, including older B&G circulator pumps, we have found leaks at the pump shaft seal that connects the electric circulator pump motor to the actual water pumping assembly.
Several causes for leaks at the circulator pump shaft bearing or pump seal
Age, wear, long-usage of the pump; these pumps often run perfectly for decades, but the additional troubles listed below can shorten pump life
Failure to lubricate the pump shaft and bearings - something that should be performed at annual service.
Worn, sagging circulator pump motor support causing torquing and wear of the bearings - elaborated below
Overheating pump motor, possibly from a lubrication failure can cause bearing failure and leaks. A pump itself can fail and can also damage the motor if mineral crud or corrosion in the pump assembly causes the impeller to jam. A bad starting capacitor can also cause pump motor failures but that probably doesn't cause pump leaks. (CAPACITORS for HARD STARTING MOTORS)
Possibly: leaks from above, dripping water into the pump motor or bearing shaft assembly from the outside. (Specluation on my part)
Possibly: improper electrical wiring, routing wires around a pump or other hot heating system component can cause an electrical failure at the pump or elsewhere, risking a short circuit or failure - source: https://www.emergencyplumber.uk.com/plumbing/central-heating-pump-problems/
At a heating system inspection we found a pile of five or six circulator pump motors in the corner of the boiler room.
The "beginner" heating tech had replaced each circulator pump motor after less than a year of service, thinking that she was simply getting "bad parts" from the supplier.
The root cause of the bearing and circulator pump motor failure in this case was not "bad parts" - rather it was that the bracket holding the circulator pump motor was not properly mounted and was slightly askew.
This out-of alignment of the circulator pump motor mean that the motor shaft was "torqued" through its sleeve bearing, leading to early circulator pump bearing failures, leaks, and noises.
Our photo above shows the mounting assembly intended to support the electric motor that operates a hot water heating system circulator pump.
Hot Water (Hydronic) Heating Boiler Circulator Articles
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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.
Anon in Article Index found at More Reading above see
CIRCULATOR PUMP WON'T STOP RUNNING
that may help
Question: noisy circulator bearing
(Feb 4, 2015) Anon said
My Grundfos 15-42fr circulator was recently moved from a vertical position to horizontal. It was quiet for a weak or so and began to make a noise just like the Taco circulator in this video. Is this noise a bearing failure? see video belink below.
Sounds like a bearing failure to me. Sometimes changing position of an electric motor combined with worn bearing(s) will display a problem that has been developing for a time.
But watch out: While I wouldn't expect a misalignment between motor and pump impeller on a Grundfos Grundfos UP15-42FR, a warning for other readers: I have seen circulator pump failures (more often with older B&G circulator pumps) due to a misalignment of the pump mounts.
(Feb 20, 2015) Donald Fletcher said:
Thanks ..., I'll try to hold out till spring, then will replace the circulator. All the talk about pulling away made me decide to place it on the hot side when I put the new indirect in. When I replace it I think I'll put the new back on the return side. I will also place a Spirotop vent in to make sure the pump don't run with air for any length of time.
Sounds right to me.
Question: air in the hot water heating piping
(Mar 10, 2015) Mark said:
I woke up this morning to the sound of air in my hot water baseboard system. When the pump is not running there is water leaking from the area between motor coupling and the pump. I have four heat zones but only one is getting heat. Then the relief valve blew. I shut the system down. How do I fix the leak?
I neglected to inform you that my pump is a B&G that is close to 40 years old.
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"Installation and Operation Instructions, Raytherm Residential Boilers," courtesy of Raypak®, and technical advisor Wayne Hoffman, personal communication 5/11/2009. Mr. Hoffman is a technical advisor with more than 30 years experience in the heating field. Raypak is a Rheem company that provides hydronic heating boilers for residential, pool, and commercial use. Raypak can be contacted at 866-583-0664 for technical support or for assistance in selecting the proper heating equipment for a specific application.
Rheem Corporation is a manufacturer of water heaters and heating equipment including Ruud heating and cooling products.
Books & Articles on Building & Environmental Inspection, Testing, Diagnosis, & Repair
Domestic and Commercial Oil Burners, Charles H. Burkhardt, McGraw Hill Book Company, New York 3rd Ed 1969.
National Fuel Gas Code (Z223.1) $16.00 and National Fuel Gas Code Handbook (Z223.2) $47.00 American Gas Association (A.G.A.), 1515 Wilson Boulevard, Arlington, VA 22209 also available from National Fire Protection Association, Batterymarch Park, Quincy, MA 02269. Fundamentals of Gas Appliance Venting and Ventilation, 1985, American Gas Association Laboratories, Engineering Services Department. American Gas Association, 1515 Wilson Boulevard, Arlington, VA 22209. Catalog #XHO585. Reprinted 1989.
The Steam Book, 1984, Training and Education Department, Fluid Handling Division, ITT [probably out of print, possibly available from several home inspection supply companies] Fuel Oil and Oil Heat Magazine, October 1990, offers an update,
Principles of Steam Heating, $13.25 includes postage. Fuel oil & Oil Heat Magazine, 389 Passaic Ave., Fairfield, NJ 07004.
The Lost Art of Steam Heating, Dan Holohan, 516-579-3046 FAX
Principles of Steam Heating, Dan Holohan, technical editor of Fuel Oil and Oil Heat magazine, 389 Passaic Ave., Fairfield, NJ 07004 ($12.+1.25 postage/handling).
"Residential Hydronic (circulating hot water) Heating Systems", Instructional Technologies Institute, Inc., 145 "D" Grassy Plain St., Bethel, CT 06801 800/227-1663 [home inspection training material] 1987
"Warm Air Heating Systems". Instructional Technologies Institute, Inc., 145 "D" Grassy Plain St., Bethel, CT 06801 800/227-1663 [home inspection training material] 1987
Heating, Ventilating, and Air Conditioning Volume I, Heating Fundamentals,
Boilers, Boiler Conversions, James E. Brumbaugh, ISBN 0-672-23389-4 (v. 1) Volume II, Oil, Gas, and Coal Burners, Controls, Ducts, Piping, Valves, James E. Brumbaugh, ISBN 0-672-23390-7 (v. 2) Volume III, Radiant Heating, Water Heaters, Ventilation, Air Conditioning, Heat Pumps, Air Cleaners, James E. Brumbaugh, ISBN 0-672-23383-5 (v. 3) or ISBN 0-672-23380-0 (set) Special Sales Director, Macmillan Publishing Co., 866 Third Ave., New York, NY 10022. Macmillan Publishing Co., NY
Installation Guide for Residential Hydronic Heating Systems
Installation Guide #200, The Hydronics Institute, 35 Russo Place, Berkeley Heights, NJ 07922
The ABC's of Retention Head Oil Burners, National Association of Oil Heat Service Managers, TM 115, National Old Timers' Association of the Energy Industry, PO Box 168, Mineola, NY 11501. (Excellent tips on spotting problems on oil-fired heating equipment. Booklet.)
Carson, Dunlop & Associates Ltd., 120 Carlton Street Suite 407, Toronto ON M5A 4K2. Tel: (416) 964-9415 1-800-268-7070 Email: firstname.lastname@example.org. The firm provides professional home inspection services & home inspection education & publications. Alan Carson is a past president of ASHI, the American Society of Home Inspectors. Thanks to Alan Carson and Bob Dunlop, for permission for InspectAPedia to use text excerpts from The Home Reference Book & illustrations from The Illustrated Home. Carson Dunlop Associates' provides extensive home inspection education and report writing material.
The Illustrated Home illustrates construction details and building components, a reference for owners & inspectors. Special Offer: For a 5% discount on any number of copies of the Illustrated Home purchased as a single order Enter INSPECTAILL in the order payment page "Promo/Redemption" space.
TECHNICAL REFERENCE GUIDE to manufacturer's model and serial number information for heating and cooling equipment, useful for determining the age of heating boilers, furnaces, water heaters is provided by Carson Dunlop, Associates, Toronto - Carson Dunlop Weldon & Associates Special Offer: Carson Dunlop Associates offers InspectAPedia readers in the U.S.A. a 5% discount on any number of copies of the Technical Reference Guide purchased as a single order. Just enter INSPECTATRG in the order payment page "Promo/Redemption" space.
The Home Reference Book - the Encyclopedia of Homes, Carson Dunlop & Associates, Toronto, Ontario, 25th Ed., 2012, is a bound volume of more than 450 illustrated pages that assist home inspectors and home owners in the inspection and detection of problems on buildings. The text is intended as a reference guide to help building owners operate and maintain their home effectively. Field inspection worksheets are included at the back of the volume.
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The Horizon Software System manages business operations,scheduling, & inspection report writing using Carson Dunlop's knowledge base & color images. The Horizon system runs on always-available cloud-based software for office computers, laptops, tablets, iPad, Android, & other smartphones