Z5T: 230
Z5B: 230
All zones are holding +/- 1 deg C EXCEPT Z3T which
after setpoint is reached, climbs very slowly (about 5 deg C/hour) and Z3B
at half that rate. Once this 5 deg deviation is reached, the system alarms
(as it should). I have confirmed the solid state relays are not "leaking"
(swapped them with good zone), the computer is setting the duty cycle of these
at 0% (once setpoint has been reached) , this has been confirmed
electrically, and there are no ground faults in the heaters, convection
fans are running. BTU has offered the customer little, if any
advice.
My theory is that "stray energy" from Z4 and
possibly Z5 are heating Z3 which, possibly due to inadequate ventilation, cannot
cool. I was hoping someone in the forum might have experienced a similar issue
and would share that experience. I haven't measured the exhaust flow rate yet,
as I didn't want to chase a "ghost", but it IS running.
It's not often I get stumped (Steve G. can attest
to that!) but this one really has me baffled.