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Old 12-05-2007, 11:05 AM   #1
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Oil Furnace - Swapping out to Programmable Thermostat

I am a relative novice with all things HVAC. I wanted to switch out a couple of my thermostats (the manual mercury type) to programmable ones for energy savings.

My home has heat only, no A/C. I have three zones, each with its own thermostat. They are connected to a Burnham oil furnace with baseboard/register heating (not forced air). When I removed my old thermostat, there were two wires: one red and one blue. The old thermostat didn't have labels on the leads, so I couldn't tell which one was power and which was the heat signal (I even studied the old thermostat to see if I could make an educated guess). Well, I've tried hooking it up both ways and the furnace doesn't seem to be getting the signal. It keeps heating to around 72 degrees (at least that's the reading on the programmable thermostat). I have the thermostat set to manual override at 60 degrees.

Between the time that I removed the old thermostat and installed the new one, I turned the furnace back on to heat the other two zones, leaving the third zone with two bare wires hanging out of the wall. Did this reset something at the furnace? I'm wondering if the furnace has a default setting when a zone has no signal? Any suggestions?


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Old 12-05-2007, 01:47 PM   #2
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The two leads are jsut an on/off switch. Connect them together the boiler is on, take them apart the boiler is off and really that's all the thermostat does, connect and separate those two wires. There is really not that more to a standard programable thermostat and the boiler isn't smart enough to know when there is no thermostat hooked up.
I can only guess as to what the problem is, but if I were to guess, you have the thermostat set to manual override vs. auto.


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Old 12-05-2007, 03:57 PM   #3
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Thanks for the reply clutch. I do have the thermostat set to manual override so that I could test it. So, the program is off and I have the thermostat set to 60 degrees. Room temp is around 72 degrees, so it should stop heating. However, it keeps the temp constant at 72-73 degrees. I would expect the radiators in that zone to go stone cold if I have it set that low. No such luck. I guess I could have a worse problem and have NO heat, but the point of the programmable thermostat was to save energy when we're not in that part of the house. Could I possibly have anything else wrong?
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