One zone too hot

George_15

I got a building with a hot water gas boiler. It has 4 circulators.. one for each zone... and 4 Honeywell relays each controlling each respective circulator.

One of the zones is too hot... looks like the circulator pump never stops. Whats the best way to tell if its the thermostat or the relay? Perhaps disconnect the wires at the thermostat or the 2 thermostat wires at the relay? If i turn the thermostat all the way down, I assume I should have zero volts at the thermostat terminals at the relay? Seems those Honeywell T87 round stats are pretty reliable. I am wondering if the relay is just stuck.

brucewo1b

Disconnect at t-stat wires at realy if stays running is either a bad relay or bad wiringto relay, if it drops out hook it back up and unhook t-stat, if it drops out its t-stat but make sure the base plate is level and the antisipator is set right. if it stays running is a short in the t-stat wire.

Bruce

oil-2-4-6-gas_3

or if you shut off the pump and it still gets too hot--your flow check could be back