Honeywell Thermostat C wire question

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  #1  
Old 10-27-15, 09:29 PM
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Honeywell Thermostat C wire question

Hello,

I am trying to connect my new Honeywell RTH6580WF Thermostat to my old gas furnace. The Current Thermostat only has two wires but there are two more unused in the wall. I took some pictures of the wiring at the furnace and the wiring diagram posted there. My question is whether or not any of the available terminals will be an acceptable "c" wire terminal?

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thanks,
Brandon
 
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Old 10-27-15, 09:33 PM
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Welcome to the forums.

There may be hope. Post the exact model number for that control. It will be letters and numbers.

Gas boiler..... right.... not furnace ?
 
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Old 10-27-15, 09:45 PM
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i thought it was a furnace but clearly I'm no expert.

Looks like it used to burn oil but was converted to gas?
these are from the outside of the case:

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This is from the inside:

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is that the right model number?
 
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Old 10-27-15, 09:57 PM
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Aha!

I believe the control model # is:

RA89C 1007
 
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Old 10-27-15, 10:25 PM
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Wow... an oldie there. Both the furnace and the control.

Unfortunately you cannot get a C connection from that control but you can still use that stat if you want. You'll need to purchase a 24vac 15-20va transformer. You would send the transformer voltage up on the two unused wires.

You'd use a plug in adapter like in the link.

24VAC 20VA Transformer
 
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