Question: One of the zones on my
hot water heating system is not working properly. How do I test a zone valve to
see if it is working?
Hydronic zone valves are used in hot water heating systems. Zone valves work in
conjunction with the thermostat, a transformer, a circulator pump and the
boiler. When the thermostat is turned up higher than the temperature in the
room, the zone valve normally turns ON and hot water is circulated through the
heating elements in that heating zone.
To test a zone valve,
first turn up the thermostat to its maximum level and feel and hear for hot
water circulating around the heating elements. If you do not feel or hear any
hot water circulating around the heating zone, pull down on the lever on the
zone valve to force the valve open. If the lever goes down easy, without any
resistance, chances are the problem is not with the zone valve. If the lever is
difficult to pull down then the zone valve is likely a problem.
With the zone valve lever in the down position, and little
resistance was felt when pulling down on it, hot water should begin to circulate
around the heating elements associated with the particular zone. If hot water
does not begin to circulate through the heating elements then chances are there
is a problem with the zone valve, circulator pump or boiler.
If there is one common circulator pump driving all of the
heating zones, and the other zones are working properly then you can rule out
the circulator pump and boiler as a problem.
If you have a multimeter handy you can also test a zone
valve to see if it is being properly powered by the transformer that
supplies a 24V voltage to it. Set the multimeter to read DC voltage up to 50
|Then measure the voltage across the wires
coming from the transformer that connect to the zone valve. If you do not
measure a 24V voltage then chances are the transformer is bad. If you do
measure a 24V voltage and there is a common circulator pump feeding all the
zones, and all the other zones are working then chances are the thermostat
or zone valve is the problem.
If after evaluating the hot water heating system and testing the zone valve
you determine that there is indeed a problem with the zone valve, call a
Photo by Mark Donovan
Do not attempt to remove the zone valve head
yourself. Removing a zone valve head while still powered by the transformer or
while it is still hot could lead to electrocution, scalding and other injuries.
For information on
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Hydronic Zone Valves from Amazon.com