How to tell if a heating circulator pump is working
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Here we discuss 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. Also you will see that
this website answers most questions about Heating System Boiler Controls on central heating systems to aid in troubleshooting, inspection, diagnosis, and repairs.
Leaks at heating circulator pumps: where leaks most often occur (circulator pump mounting flanges)
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.
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 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.
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.
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).
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.
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 (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.
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 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.
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 s/he was simply getting "bad parts" from the supplier.
The root cause of the bearing and circulator pump motor failure in this case 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 (left) shows the mounting assembly intended to support the electric motor that operates a hot water heating system circulator pump.
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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
Our recommended books about building design, inspection, and repair, and about indoor environment testing, diagnosis, and cleanup are at the InspectAPedia Bookstore.
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.)
InspectAPedia® Home & Site Map - Building & Environmental Inspection, Testing, Diagnosis, Repair, & Problem Prevention Advice: In-depth research & advice on diagnosing, testing, correcting, & preventing building defects & indoor environmental hazards. Unbiased information, no conflicts of interest.
The Mold Information Center: What to Do About Mold in Buildings, When and How to Inspect for Mold, Clean Up Mold, or Avoid Mold Problems
Environmental Inspection, Testing, & Diagnosis On-Site IAQ, Gas, Air Testing, Mold Investigation, Sick Building Diagnosis, Lab Services, & Remediation Plan Preparation - indoor air quality testing, problem source determination, supporting lab work, written remediation plan addressing removal of environmental and other hazards and prevention of their recurrence.