Rheem furnace thermostat upgrade

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  #1  
Old 03-08-17, 09:56 AM
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Rheem furnace thermostat upgrade

I have a Rheem classic 90 plus multi stage natural gas furnace/ac/humidifier unit that was new in 2000. I would like to upgrade to one of the newer thermostats, something I can see in the dark and make changes in the settings from my phone. When I reached out to Rheem they would not tell me which thermostats will work correctly with what I have (even though they sell a few like this) , they recommended that I contact my local repair center. How hard can it be to to connect 9 wires to a Tstat especially when my background is electronics?
Any help is appreciated.
 
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Old 03-08-17, 10:52 AM
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Post the model number of the furnace and we can help you. 9 wires??
 
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Old 03-08-17, 10:58 AM
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Yeah... 9 wires is a little scary.
 
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Old 03-08-17, 11:12 AM
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Rheem Classic 90 Plus furnace
 
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Old 03-08-17, 11:14 AM
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That's the series name. You can find the model number in the burner section of the furnace.
 
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Old 03-08-17, 11:14 AM
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That's a trade name. The model number is behind the burner access door.
It's on an ID plate on the side wall near the burner.
 
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Old 03-08-17, 11:19 AM
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Will this help? This is the wiring in the current Contour Comfort control stat.

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Last edited by PJmax; 03-08-17 at 02:39 PM. Reason: enhanced picture
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Old 03-08-17, 12:08 PM
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The only terminal I don't recognize is V. I think the Honeywell RTH 6580 WF would work for you.
 
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Old 03-08-17, 03:00 PM
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The model number is RGFD-07EMCKS
 
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Old 03-08-17, 04:01 PM
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Correction the black wire is connected to SO not V. I think Pj could find more info on this model than I can. He should be along later this evening.
 
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Old 03-08-17, 04:14 PM
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With the WiFi stat you'll get wifi control but you will lose the variable heating rate. The V terminal stands for variable furnace modulation controlled by a modulating thermostat.

This would be the 6580 wiring......
Red = R/Rc (leave jumper in place)
Tan = C
Green = G
Yellow = Y
White = W
Brown/Black = may possibly go to W2 but if it does..... dip switches at the furnace will need to be changed for two stage heating.

Furnace manual........
/Installation_instruction_Rheem_RGFD_en.pdf
 
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Old 03-09-17, 03:59 AM
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Ouch, not sure I want to drop the modulating feature, that changes everything.

Thanks for the PDF, I have a car copy but its rough.
 
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Old 03-11-17, 06:13 AM
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I had sent a message to Honeywell regarding this and after reviewing the pdf you sent they thought these Honeywell thermostats should work correctly:

RTH6580WF
RTH9580WF
TH8321WF

They said
However the V terminal will go into W2 instead of V.
 
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Old 03-11-17, 08:13 AM
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Correct.... that's what I said. You lose the variable firing and it becomes two stage heating.
There are jumpers that will need to be changed.

The Honeywell stats don't offer variable operation.
 
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Old 03-11-17, 10:36 AM
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Bummer, I really want to keep it modulating.
 
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Old 03-11-17, 12:14 PM
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How about the Aprilaire 8920W, that looks like it will even make toast!
 
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Old 11-07-17, 04:25 PM
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It might do toast but according to the manufacturer it wonít operate the modulating furnace. Iím surprised that no one makes a thermostat for this.
 
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Old 11-07-17, 05:17 PM
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I’m surprised that no one makes a thermostat for this.
Not yet....... that I'm aware of.
 
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