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Discussion Starter #1
I have a gas forced air furnace with 2 zones, upper level and lower level. The zones are controlled by a Honeywell mini zone controller EMM-3. My problem is that when upper level zone calls for heat, lower level zone lights up and also heats even when the thermostat is in the off position or set lower than room temperature. Any ideas? I tried moving the two zones to 2 and 3 on the board, but that did not help. In the photo one thermostat is off and as you can see both zones are lit up.

 

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Disconnect the zone 2 thermostat wire and see if it does it. Also, push the reset button and hold it in for a minute to see if it clears any corruption the board may have.
 

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I pushed reset button. Upper level came on and lower level stayed off just like it is supposed to. Unfortunately after the first cycle it is back to like it was. I think this would eliminate a wire short and put the blame on the EMM-3 board?????
 

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Did you have the second zones thermostat wires disconnected from the panel.
 

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Discussion Starter #6 (Edited)
OK, today I had a chance to disconnect the thermostat from the second zone(lower level), I left the damper wires hooked up. The first zone(upper level) called for heat and sure enough, the lower level, with no thermostat hooked up, lit up and heat was also directed there.

Another note: When the Lower level calls for heat and the upper does not, Just the LL led lights up and all heat goes to LL. That works properly.
 

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I would have reset the board also for the test. Then if the second zone still opened when the first zone called. I'd condemn the board.
 
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Discussion Starter #8 (Edited)
Well first of all beenthere, thank you very much for responding and helping me out. I redid the test by pulling all 5 thermostat wires from the EMM -3, then hit boot button, the zone came on again. I installed a new board(I had one here because living in a small town I stock a few parts for weekend no heat situations), the result was the same. Oh well, I gave it a shot. The only reason I wanted to keep the lower level cooler was my wife exercises in the AM and when she is done it is programmed to heat up. Last summer my fan quit and i had to call a heating company. They replaced the fan curcuit board in the furnace. Hopefully they hooked the wires correctly and did not cause this.

Thanks again,

Mike
 

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Might want to switch zone numbers. make the basement zone 1 and the other floor zone 2, and see if it still does it.
 

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Discussion Starter #11
Might want to switch zone numbers. make the basement zone 1 and the other floor zone 2, and see if it still does it.
I switched the zones but the problem follows the upper level. When it calls for heat, it also activates the lower level even if lower is off or set under present room temp. :furious:
 

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Sounds like the problem is in that zone, its wiring.
 
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