Thermostat Replacement


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Old 11-25-14, 12:12 PM
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Thermostat Replacement

Hi, I am new here, I have spent many hours reading here, but cant find exactly what I'm looking for, so please forgive me if this has already been posted...

I currently have a Honeywell TH8320U1008 thermostat, it's acting all derpy, the lights go out when you try to change the temperature, the heat stays on for hours, etc. I have been told that I should start with the easiest thing to fix and go from there, so I went and bought a new thermostat, a Honeywell Rth221B1021, it is much smaller, much simpler and cheap.

My old thermostat is completely unnecessary in my house, it is too much thermostat for the house. I have heat and AC, no heat pump, no fancy accessories, it is hooked up with 5 wires. Yellow, green, white, red and blue.

Old thermostat is hooked up like so..
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The new, cheaper, easier to use thermostat has this...
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If what I have read here and a bunch of other places is correct, I can hook up the Yellow, Green, Red and White and just tape off the blue, right? The only function that I can find for the blue wire on my old thermostat is that the old one has a light up panel, the new one doesnt. Am I reading all this correctly?

Edited to add, the new thermostat has no "C" spot on it (which is what it was hooked up to on the old thermostat), so if I do indeed need the blue wire, where do I put it?

It has B and O, which are separate and I think they are used for AC units with heating capabilities? and the rest are G,Y,W,R and RC
 
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Old 11-25-14, 12:29 PM
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I can hook up the Yellow, Green, Red and White and just tape off the blue, right?
Yes, you are correct. The standard colors are:

Red=24V connect to R
Green=Fan connect to G
White=Heat connect to W
Yellow=Cooling connect to Y

Jumper between R and RC.
 
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Old 11-25-14, 12:33 PM
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Thanks! Now I just have to hope that this fixes it, because two days before Thanksgiving is NOT the time to have to call some poor guy to come fix my furnace. Thanks a bunch!
 
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Old 11-25-14, 12:41 PM
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Make sure you turn off power before switching the thermostat or you will probably blow the low voltage fuse. Also, make sure to check the manual as there is usually a jumper to set for fan operation.
 
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Old 11-25-14, 01:08 PM
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OK, the power at the furnace, correct? Or just flip the breaker off completely?

Also, as far as the fan goes, I dont see anything mentioned about a jumper for the fan, but the instructions have this...Name:  fan.jpg
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This is also confusing to me. I get billed Gas for heat, so I was thinking that I have a gas system, but then it says under electric "this setting is for systems that allow the thermostat to control the fan in a call for heat, if a fan wire is connected to the G terminal" So, is it a gas system, or an electric system? I will have a wire connected to the G terminal.

I know I sound like a freaking moron, sorry about that!
 
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Old 11-25-14, 01:17 PM
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If you have a gas furnace there is probably a service switch on or near it that looks like a light switch. You can turn power off there. As far as the jumper set that to the Gas or Oil setting.
 
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Old 11-25-14, 01:23 PM
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OK, thanks! Hopefully I dont blow my house up. You have been super helpful!
 
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Old 11-25-14, 01:30 PM
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You are welcome. Post back if you have any problems.
 
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Old 11-26-14, 08:17 AM
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Thermostat installed in less than 15 minutes, got it up and running and then the heat went off and wouldnt come back on. Went to the basement and realized that the pilot light was on, trying to light the burners and failing. Did a quick YouTube search and decided to take the ignition sensor dealie out and clean it up, it was a little funky, but apparently that all it takes. Cleaned it up, put it back in and worked like a charm all night! Thanks so much for your help!
 
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Old 11-26-14, 08:23 AM
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Glad to hear your were able to quickly troubleshoot and resolve your issue and thanks for the update.
 
 

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