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Upgrade our 2 wire thermostat to digital?

Asked Oct 23, 2006, 05:10 PM — 26 Answers
We have a thermostat that only has 2 wires, red and white coming out of the wall, and we want to change it to a digital thermostat with slots of W2, G, E, why, C, B O, are or we also have a unit that has slots W1, G, why, C, B, O, R

So my question is this: Are we able to use either of the 2 new thermostats in place of the current ugly one we have?

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26 Answers
NorthernHeat's Avatar
NorthernHeat Posts: 1,457, Reputation: 699
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#2

Oct 23, 2006, 07:02 PM
If you only have two wires it means you have heat only, no fan on/auto or cooling. Hook up the red wire to are or Rh and the white to W1. That's all you need to do.
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labman's Avatar
labman Posts: 10,673, Reputation: 3050
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#3

Oct 23, 2006, 07:47 PM
Read the directions. Some may require the common side of transformer to be connected to the C or B terminal. Many don't
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NorthernHeat's Avatar
NorthernHeat Posts: 1,457, Reputation: 699
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#4

Oct 23, 2006, 07:50 PM
Quote:
Originally Posted by labman
Read the directions. Some may require the common side of transformer to be connected to the C or B terminal. Many don't
Just C (common) Blue is for Rheem/Ruud/Weatherking heat pump reversing valve, Orange for about all other makes of heat pumps
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fish4brew's Avatar
fish4brew Posts: 2, Reputation: 1
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#5

Oct 23, 2006, 10:49 PM
Well, I hooked the red wire to the are terminal, and the white wire to the W1/W2 terminals on both units and no luck. However when I hooked the Red to are, and the White wire to C, OR the Red wire to B and again the White wire to C, it displays, BUT the heater doesn't turn on? The instructions don't tell how to hook up a two wire(red/white) thermostat. Anyone know where to put the red and white wires into the terminals? On another note, the instructions kept mentioning that multi stage thermostats shouldn't be used on single stage units....maybe this is the problem..how do I know if I have a single versus multiple stage unit?
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labman's Avatar
labman Posts: 10,673, Reputation: 3050
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#6

Oct 24, 2006, 03:20 AM
Chances are, if only had 2 wires originally, you have a single stage furnace. Look at it. If it just has a W terminal and no W1 or W2, it is a single stage furnace. Even if like mine, it could be wired as a 2 stage furnace, you will have to continue to run it as a single stage unless you run a cable with more wires.
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jeepiz's Avatar
jeepiz Posts: 1, Reputation: 10
Junior Member
  
#7

Oct 15, 2010, 05:32 PM
NorthernHeat, you rule! I just struggled for about 2 hours wiring and re-wiring my new thermostat--didn't work until I read your simple R/Rh and W1 instruction above. The Honeywell directions and website were about as useful as a cookbook would've been. Thank you!
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JD2883719's Avatar
JD2883719 Posts: 1, Reputation: 10
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#8

Nov 21, 2010, 09:27 AM
+1 for NorthernHeat - THANK YOU! Worked perfectly!
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Hannnydad's Avatar
Hannnydad Posts: 1, Reputation: 10
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#9

Dec 11, 2010, 09:23 PM
+2 for northernhear --- Got two thermostats in my house working. Thank you for the help
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douglasvb's Avatar
douglasvb Posts: 1, Reputation: 10
Junior Member
  
#10

Dec 25, 2010, 08:28 AM
I also have a 2-wire setup. Do I need a battery powered thermostat? Because Rh and W1 don't seem to work for me on the new tstat.. Screen is blank.. No lights.. Are and W1 work on the old tstat, but its battery powered. Thanks!
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