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Here we explain simple procedures for determining whether the circulator pump is working on a heating system. 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.
Contact us to suggest text changes and additions and, if you wish, to receive online listing and credit for that contribution. © Copyright 2009 Daniel Friedman, All Rights Reserved. Information Accuracy & Bias Pledge is at below-left. Use links at the left of each page to navigate this document or to view other topics at this website. Green links show where you are in our document or website.
How to tell if the circulator pump is working - some circulators are quiet - which pipes to feel
First, before checking the circulator pump for proper operation, we need to be sure that the heating system controls are calling for heat:
1. The heating boiler must be turned on and able to run
2. The thermostat must be set up to call for heat
3. In response to the thermostat you should hear the heating boiler turn on and run;
4. You can then examine the heating system distribution piping leaving and returning to the heating boiler, identify the circulator pump (or pumps if there is more than one), and feel the heating water piping at the pump(s).
5. Identify the circulator for the heat zone where you have turned up the thermostat:
Checking the Operation of a Single Hot Water Heat Circulator Pump - a Single Heating Zone
If there is only one thermostat, one heating zone, and one circulator pump it's simple, there is nothing to sort out, continue with step 6 below. There will be no zone valves, just a single pump and its controls to turn the circulator pump on and off.
The heating distribution piping in a one-zone building may still be divided into multiple "branches" or sub-loops. If that is the case, you might be able to convert this system to individual zone controls by adding zone valves at the individual heating water piping loops - provided that the loops are arranged in parallel, not in series.
Checking out the Operation of a Multi-zone Heating System Using a Single Circulator Pump
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If there are multiple thermostats there may still be only one circulator (if zone valves are installed) and individual heat zones are controlled by motorized zone valves that open or close to let heating water flow through that heating pipe loop. In that case the same procedure as below for "feeling the circulator piping" is used but you feel the piping at the zone valve as well - since if a zone valve is not opening no hot water will flow. Our photo (left) shows a 6-zone hot water heating system using six individual zone control valves and a single circulator pump. See ZONE VALVES for details about how these devices work and how they are inspected and repaired. |
Checking out the Operation of a Multi-zone Heating System Using Multiple CIrculator Pumps
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In this case if you don't know which circulator pump and pipe loop supplies the zone for which you turned up the thermostat, just go to step 6 just below, but feel the piping at each circulator pump. Our photo (left) shows an 8-zone hot water heating system using eight individual Bell & Gossett™ circulator pumps. Notice those rust marks at the bottom pump flange at some of these units? All eight pumps had been installed in the previous two years - at a previous inspection we found the predecessor pumps leaking so badly that the floor of the boiler room was puddled with heating water. The installer needs to inspect, clean, and re-make the leaky connections on these new circulator pumps to avoid a repetition of the same problem. |
How to know if a particular hot water heating zone is working or calling for heat:
Feel the Hot Water Heat Piping at the Circulator Pump: You can feel the pipe at the circulator pump - doesn't matter which side - in or out flow - since if the pump is running the pipe will get warm, then hot.
If the circulator is on the pipes that are LEAVING the boiler and sending heat into the building (not the best location) it's better to feel the pipe on the outlet side of the circulator since the pipe at the inlet side might be hot just by convection heat rising from the boiler.
If the circulator pump is on the RETURN side of the heating piping loop (the usual and better location) then you can feel the pipe at the circulator pump - doesn't matter which side - in or out flow - since if the pump is running the pipe will get warm, then hot if it is successfully moving hot water out of the boiler and through the heating pipes.
Why Might Multiple Heating Zones All Run at Once When Only One Thermostat is Calling for Heat?
If all of the heating system's valves stopped working some time ago, someone may have latched them in the "open" position - so if any of the thermostats called for heat, every heating zone would receive heat even though only one thermostat is calling for heat.
See Zone Valves for details about zone valve operation, inspection, diagnosis, repair. There we include photos including a zone valve control lever on the side of a Honeywell valve - in the auto position.
If you see that the manual zone valve control lever is "latched" into the "on" position, try un-latching it and then watch to see if the valve operates (and the lever moves) in response to a call for heat at that zone.
See HEATING LOSS DIAGNOSIS-BOILERS diagnostic links if this is the case.
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Use links just below or at the left of each page to navigate this document or to view other topics at this website. Green links show where you are in our document or website.
BOILERS, HEATING
BOILER OPERATION DETAILS
BOILER CONTROLS & SWITCHES
Air Bleeder Valves
Aquastat Functions
BOILER LEAKS CORROSION STAINS
BOILER OPERATING PROBLEMS
BOILER PARTS LIST
Boiler Pressure Controls & Settings
Cad Cell Relay Switch Flame Sensors
Circulator Pumps & Relays
Circulator Pumps vs. Zone Valves
Circulator Pump Trouble List
Checks for Circulator Operation
Single Zone Heat Tests
Multi-Zone One Circulator Tests
Multi-Zone Multi-Circulators Tests
Individual Zone Tests
Un-wanted Heat in Some Zones
Leaks at Circulators
Circulator Motor or Bearing Failures
Where to Mount Circulator Pumps
Other Circulator Controls
Expansion Tanks
Gauges on Heating Equipment
Limit Switches, Boilers
Low Water Cutoff Valves, Boilers
Mixing Valves
Relief Valves - TP Valves
Reset Switch - Primary Control
Reset Switch - electric motors
Spill Switches
Stack Relay Switch
Thermostats
Water Feeder Valves, Hydronic Boiler
Zone Valves
WATER HEATERS
ZONE VALVES
- "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.
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More Information on Building Diagnostic Inspections and Repairs
- Carbon Dioxide Gas Toxicity
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- Dust from HVAC? An Investigation of Indoor Dust Debris Blamed on a Heating/Cooling System Reveals Carpet Dust
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- Home Heating System Should Be Checked [for proper venting and for CO Carbon Monoxide Hazards - DJF]
- Inspection Procedures for Oil-Fired Heating Systems Detailed step by step approaches for inspecting complex systems]
- Lennox Pulse Furnace Safety Inspection/Warranty Program: Carbon Monoxide Warning
- Oil Tanks - The Oil Storage Tank Information Website: Buried or Above Ground Oil Tank Inspection, Testing, Cleanup, Abandonment of Oil Tanks
- Oil Tanks Above Ground, UL Standards, guidance for home owners, buyers, and inspectors
- Plastic Heating Vent Pipe & Other Heating Safety Recall Notices
- Weil McLain Model GV Gas Boiler/gas valve CPSC recall/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 Steam Heating Systems", Instructional Technologies Institute, Inc., 145 "D" Grassy Plain St., Bethel, CT 06801 800/227-1663 [home inspection training material] 1987
- "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.)
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