Honeywell RTH8500D installation not working


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Old 01-19-13, 12:14 PM
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Honeywell RTH8500D installation not working

I have a Lennox G803-120-1 forced air gas furnace (circa 1985) with an old Honeywell rectangular thermostat (model/year unknown but the kind with a mercury filled tube) that has only 2 wires: black and white. The thermostat has no wire/letter labels as far as I can tell. Fortunately, I have the furnace schematics showing a R and W for the thermostat, but when I hook up the wires to the new RTH8500D (black to R, white to W) I get nothing. The breaker is on, the furnace power switch is on, and the batteries are freshly charged, so I don't think that's the issue. Even if I switch the wires (black to W, white to R, as I've read that it shouldn't matter) I still get nothing on the new thermostat screen. Is there something obvious that I'm doing/not doing?
 
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Old 01-19-13, 01:46 PM
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The stat should give you a display when it is removed from the wall when batteries are functioning and properly orientated.

You probably got a dud.

In my opinion Honeywell is the best option for thermostats but they are not perfect.
 
 

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