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Heating zone circulator pump bypass: how to circulate hot water in a hydronic heating system if the circulator or zone valve is not operable: bypassing the heating circulator pump or latching the zone valve open can get heat into the building even if the circulator pump itself is not working - maybe.
Our page top photo shows that a heating circulator pump motor has been removed completely while waiting for replacement. How can we get heat to flow in this building?
This article series describes how to diagnose & fix circulator pumps on hot water or hydronic heating systems.
Bypass the Circulator: Question: OK to run the boiler if the circulator is not working right?
(Feb 8, 2012) Kelly said:
Can you continue to run the boiler if the circulating pump is not working properly? The house is heating but I'm concerned about how safe this is.
The pump tries to turn on but is not and i believe it may be the coupler and will have someone out to fix it but in the meantime; i just don't want to cause any more damage by keeping the heat on.. it's only 25 deg's today so i'm hoping it's not dangerous.
In general (which means we don't know a thing about your heating system so this may be wrong for you), heating boilers are controlled by one or more temperature-sensing devices - aquastats - as well as other safety controls. If a circulator pump is not working but the boiler is heating up, the boiler should not get hotter than the upper safety limit set by its HI LIMIT control.
Hot water will still circulate in some heating systems that use circulator pumps or even zone valves, even if the circulator pump is not working. Hot water will rise out of the boiler by convection and cooler water will return to the boiler's return side by the same process
In some heating systems one can over-ride a check valve at the boiler by manually turning a lever, and similarly one can manually open some heating zone valves.
In my photo at above left, push the metal lever all the way to the left then down to latch it in the "OPEN" Position.
The result is that heat will be delivered to the building by convection - more slowly than if the circulator were running - but still effectively.
In fact more than once I found this situation in homes that had hot water heat but no working circulator. The home would heat to a satisfactory temperature, but more slowly than occupants might have preferred.
This is also a stop-gap or backup method of keeping a building heated while waiting to replace or repair the circulator or circulator relay.
Watch out: in many but not all hot water heating systems that use a circulator pump, flow-control or flow-check valves and zone valves, you can get hot water to circulate by natural convection using the steps above. The thermostat calls for heat and provided that the boiler temperature is below the CUT IN setting on the boiler primaruy control or aquastat the boiler will cut-on, heating its water. Heated water will then rise in the heating distribution piping above the boiler and into the building.
Heat delivered by these methods will arrive more slowly than if a working circulator pump were in operation
It may be necessary to manually open the flow-control valve or check valve (shown above) in for hot water to flow.
If a zone valve lacks a manual open feature OR if the zone valve head has jammed and won't operate then a heating system with zone valves won't circulate heat through that zone.
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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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