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Dekuyper 06-25-2008 06:39 PM

Thermostat Question
 
Hello all,

I replaced an old mechanical thermostat with a digital one. I was happy to find that when I disconnected the old one it had the standard 5 wires that I needed for the new one. Red RH, Blue RC, Green, White and Yellow.

I connected the new one and got erratic behavior out of it. The fan always seemes to work. When switched to "heat" the pilot does not light the furnace. When switched to cool, the outside unit sometimes comes on, sometimes doesn't. When switched to auto, the fan refuses to come on at any temperature.

I know the wiring is good, because I can use the jumper wire and touch the RH to any other wire and the appropriate device will kick on. I just can't get it all to work with the faceplate of the thermostat installed.

Any help would be appreciated.

Thanks!

chris75 06-25-2008 06:45 PM

When you removed the old t-stat, were the the wires going to the same terminals that you used on the new t-stat? in other words, was green actually the "G" terminal?

Also, if you are actually using RC & RH, make sure you remove the jumper between the two at the t-stat.

Dekuyper 06-25-2008 11:18 PM

Wires are right. Again, I can touch the contacts of the Rh and W with a spare piece of wire and the unit will kick on. Same works by touching the contacts of the Rh and G to turn the fan on.

And the jumper is removed from the RH and RC terminal.

Right now, Its working on Cool - on, and Cool - auto, but the heat setting doesn't fire up the furnace.

chris75 06-26-2008 06:42 AM

Quote:

Originally Posted by Dekuyper (Post 133772)
Wires are right. Again, I can touch the contacts of the Rh and W with a spare piece of wire and the unit will kick on. Same works by touching the contacts of the Rh and G to turn the fan on.

And the jumper is removed from the RH and RC terminal.

Right now, Its working on Cool - on, and Cool - auto, but the heat setting doesn't fire up the furnace.


So when you manually jump out RH and W it works perfect, but as soon as the t-stat is installed it wont? I would try replacing the t-stat with a new one.

gregzoll 06-26-2008 08:49 AM

What is the Manufacturer & Model of the Thermostat. Some like the Honeywells have to be programmed through the settings section to work correctly.


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