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AIR CONDITIONING & HEAT PUMP SYSTEMS
BACKDRAFTING HEATING EQUIPMENT
BACKUP HEAT for HEAT PUMPS
BANGING HEATING PIPES RADIATORS
BLOWER FAN OPERATION & TESTING
BOOKSTORE - InspectAPedia
BTU USAGE MONITORS
CARBON MONOXIDE - CO
CIRCULATOR PUMPS & RELAYS
DIAGNOSTIC GUIDES A/C / HEAT PUMP
DIAGNOSE & FIX HEATING PROBLEMS-BOILER
DIAGNOSE & FIX HEATING PROBLEMS-FURNACE
DIRECT VENTS / SIDE WALL VENTS
DRAFT REGULATORS, DAMPERS, BOOSTERS
DUCT SYSTEM & DUCT DEFECTS
ELECTRIC MOTOR DIAGNOSTIC GUIDE
FAN, AIR HANDLER BLOWER UNIT
FLOODED HEATING EQUIPMENT REPAIR
FLUE SIZE SPECIFICATIONS
GAS BURNER Flame & Noise Defects
GAS PIPING, VALVES, CONTROLS
GEOTHERMAL HEATING SYSTEMS
HEAT PUMPS, DIAGNOSIS, REPAIR
HEATING COST SAVINGS METHODS
HEATING OIL PIPING TROUBLES
HEATING OIL TANKS
HEATING SYSTEM NOISES
HEATING SYSTEM TYPES
GAS LP & NATURAL GAS SAFETY HAZARDS
MANUALS & PARTS GUIDES - HVAC
MIXING / ANTI-SCALD VALVES
MOTOR OVERLOAD RESET SWITCH
NOISE, HEATING SYSTEMS
ODORS FROM HEATING SYSTEMS
OIL FILTERS on HEATING EQUIPMENT
OIL FILL PIPE LEAKS
OIL SPILL CLEANUP / PREVENTION
PLASTIC Plexvent / Ultravent RECALL
PUFFBACKS, OIL BURNER
RELIEF VALVE LEAKS
Reset Switch - Heater Primary Control
RESET SWITCH - ELECTRIC MOTOR
Reset Switch - Stack Relays
SAFETY, HEATING INSPECTION
SAFETY RECALLS CHIMNEYS VENTS HEATERS
SOLAR HEATING SYSTEM DESIGNS
SOOT on OIL FIRED HEATING EQUIPMENT
STEAM HEATING SYSTEMS
THERMOSTATS, HEATING / COOLING
VIDEO GUIDES: Heating System Videos
WINTERIZE A BUILDING
WOOD, COAL STOVES & FIREPLACES
WOOD STOVE SAFETY
ZONE VALVES, HEATING
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.
This article series answers most questions about Heating System Boiler Controls on central heating systems to aid in troubleshooting, inspection, diagnosis, and repairs.
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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:
If there is only one thermostat, one heating zone, and one circulator pump it's simple, there is nothing to sort out, continue with INDIVIDUAL HEAT ZONE CHECK. 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.
[Click to enlarge any image]
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, HEATING for details about how these devices work and how they are inspected and repaired.
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 INDIVIDUAL HEAT ZONE CHECK 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:
Listen to the circulator pump: is it running? Bell & Gosset circulators are generally audible, making some electrical motor noise. Grundfoss circulator pumps are quieter but should be audible. Taco circulator pumps are often so quiet that you cannot rely on sound (or I can't), but it's easy to go on to the next step: feeling piping temperatures.
Incidentally if a heating zone circulator pump is very noisy or has become more noisy than when it was installed, there may be a problem with a failing motor bearing, pump assembly bearing, or pump impeller.
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.
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, HEATING 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.
Watch out: hot water may be circulating in a hyronic heating system even if no thermostat is calling for heat, for example if a Flow-Control check valve has stuck in the open position or has been left manually open. See CIRCULATOR PUMP WON'T STOP RUNNING for details.
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