Getting HEAT in Z1 when furance comes on for Z2 & Z3

[2eggsandtoast]

We have a three zone systems (Zone 1: 1st Floor Bonus room, Zone 2: 1st Floor Dinner Room, Zone 3: 2nd Floor Bed Room). We have oil heat (Thermidor Furnace) and an EWC-ST-3D control unit. Our main control is the bonus room Zone 1 that has the on/off switch for the entire house. For many years, we were able to keep the thermostat in the "On" position and set it to 50 degree in Zone 1 to keep the heat off in the bonus room and zones 2 and 3 would go on and off as required by the thermostat in their respective rooms. Currently, we are not getting heat in zones 2 or 3 unless the thermostat is going on in Zone 1(This has been corrected). We are now getting heat in Zone 2 and 3 when the thermostat calls for it in Zone 2 and 3 but the heat is also coming out in Zone 1. It sounds like a door is not closing in the duct to stop heat from traveling to Zone 1. Any idea how to trouble shoot?

[Erik W.]

It sounds like you damper motor may not be closing properly, to know for sure you would have to test it electrically with a volt meter. if the motor should be open than there should be 24 volts between 1 and 4 on the motor. if the motor is closed than the motor should have 24 volts between 1 and 6.

Erik Wnoroski
EWC Controls, Inc.
385 State Route 33
Englishtown, NJ 07726
800-446-3110 ext 483