Diagnose Stuck or "Dead" Zone Circulators on Hot Water Heating Systems
Reader question: My heating zone circulator won't start-up
(Oct 29, 2011) Mark said:
I have a Weil-McLain furnace/boiler model no. CGM-5-PI. I just turned on the heat system two days ago and I noticed the circulator pump is not spinning its motor. I bleed all the valves on all the radiators.
The two upper levels get heat on the radiators, but the one on the entrance level is not getting heat. Is this caused by the pump not working? Is there any danger/risk of running the heat with the circulatory pump not working?
How much would it cost to replace the circulatory pump? Any information would be helpful. Thanks.
(Nov 24, 2012) annonymous said:
circulator pump goes on when heat called, runs thru cycle, but doesn't come again.....burners come on,but not circulator which in turn system goes off
Mark if the circulator pump won't start when the boiler temperature is sufficently high that it should, you would check:
1. the thermostat is calling for heat and the room temperature is below the thermostat set temperature
2. the boiler temperature is above the circulator cut-in temperature controlled by the aquastat
5. the circulator pump itself is not damaged, jammed, frozen
In answer to your cost question, Grundfoss & Bell & Gossett heating zone circulator pumps are typically in the range of $100. to $300. depending on the pump model.
Question: should the circulator pump come on right away?
(Oct 27, 2011) Steve said:
My daughter bought a house with hot water heat. I bled the radiators, oiled the circulator pump and turned up the thermastat in order to check the operation. The circulator pump did not start to opereate until the boiler temp read 150 degrees.
The pump is hooked up to an aquastat (the thermastat located against the pipe exiting the boiler) which is set at 140 degrees. The radiators do heat up. Shouldn't the pump come on right away?
Steve, on a very common hot water heating system installation the aquastat is a combination control that includes a HI LO and DIFF setting - the LO and DIFF settings control the boiler when no heat is being called for and maintain heat in the boiler to provide domestic hot water through a tankless coil - that might not even be present or not in use on some installations.
If that general control and approach are in use on your system and if your system is hooked up in the manner typically used in the U.S. (not in Canada) the circulator won't turn on until the temperature is sufficiently high in the boiler.
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"Instruction Manual, Bell & Gossett Series LR Circulators" P86101D, Mayu 2012, Xylem Inc. 8200 N. Austin Avenue Morton Grove, Illinois 60053 Phone: (847) 966-3700 Fax: (847) 965-8379 www.xyleminc.com/brands/bellgossett
"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.
Bell & Gossett Air Separators and other heating system components, 8200 N. Austin Ave., Morton Grove IL 60053, USA - Tel 847 966-3700 Fax 847 965-8379 . Air separators are discussed by B&G at http://www.bellgossett.com/homeowners/BG-airseparator.asp
Taco air scoops and other heating system components & controls: Taco Inc., 1160 Cranston Street, Cranston, RI 02920 / (401) 942-8000 / Fax (401) 942-2360 Taco (Canada) Ltd., 6180 Ordan Drive, Mississauga, Ontario L5T 2B3 / (905) 564-9422 / Fax (905) 564-9436 www.taco-hvac.com
Taco also has some helpful FAQs that are useful in diagnosing circulator problems - see http://www.taco-hvac.com/en/faq.html#
Sparco air purgers, air scoops, and other heating system components & controls:
"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
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
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