Original message
| mdiaddez
 |  "York T874R Sub Q674L to Honeywell RTH7400"
, posted Sat 25 Mar 20:18:  
Like many I am looking to upgrade my heat pump to a programmable thermostat and am having issues with the wiring...Honeywell is of no assistance.
The current base: Q674L has the following connections (no jumpers):
W, B, G, R, X, O, Y
I am fairly confident of the following connections to the RTH7400:
R --> R
G --> G
W --> Aux
Y --> Y
I am unsure of B, X, O ? From the York manual, B and X both appear to be related to EM Heat. While O is the "Cool Changeover Valve".
Any idea where these wires connect to on the RTH7400 with OB, C, L, E as available terminals?
Thank you for any assistance!!
MattyD
[this message was edited by mdiaddez on Sat 25 Mar 20:19] |
| Replies:
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| Xenos
| "Re(1):York T874R Sub Q674L to Honeywell RTH74" , posted Sat 25 Mar 20:44
What thermostat is on the subbase? the combination will make a differece.
Xenos.
The best way to escape a problem is to solve it.
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| | Xenos
| "Re(2):York T874R Sub Q674L to Honeywell RTH74" , posted Sat 25 Mar 20:47
Common is either B or X, I just need both numbes to look it up. I would think B is common and X is the light but I just want to make sure as X could be common and B heatswitchover.
Xenos.
The best way to escape a problem is to solve it.
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| | mdiaddez
| "Re(3):York T874R Sub Q674L to Honeywell RTH74" , posted Sun 26 Mar 06:38:
...sorry must have been removed from post heading.
The original thermostat is a YORK T874R (appears to be same as Honeywell version) with Subbase Q674L. I am upgrading to Honeywell "RTH7400". I did wire it up and this is how it is set.
R-->R, G-->G, W-->Aux, Y-->Y, B-->C, X-->E, O-->O/B.
Setup Options = #170 = 7 , #190 = 0.
The unit appears to be working...it just kicked on per schedule and warm air is blowing...I don't smell smoke :) I also want to make sure AUX second stage heat is being used everytime the unit turns on...wouldn't think it would be an issue though as that is controlled by the W-->Aux lead which appeared to be a straight forward connection?
Thanks for responding and your assistance!
MattyD
[this message was edited by mdiaddez on Sun 26 Mar 06:55] |
| | Xenos
| "Re(4):York T874R Sub Q674L to Honeywell RTH74" , posted Sun 26 Mar 08:50:
According this this link, tape off the X terminal as it's no required.
Xenos.
The best way to escape a problem is to solve it.
[this message was edited by Xenos on Sun 26 Mar 12:42] |
| | mdiaddez
| "Re(5):York T874R Sub Q674L to Honeywell RTH74" , posted Sun 26 Mar 10:51
I am sorry Xenos but the link within Honeywell that is provided will not resolve. So are you saying that everything should function fine with the wiring and function settings that I have made, except the X terminal should be taped and not connected?
Thank you so much for your assistance!!
MattyD
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| | Xenos
| "Re(6):York T874R Sub Q674L to Honeywell RTH74" , posted Sun 26 Mar 12:43
Yes.
Xenos.
The best way to escape a problem is to solve it.
|
| | mdiaddez
| "Re(7):York T874R Sub Q674L to Honeywell RTH74" , posted Sun 26 Mar 13:46
Thanks!!!
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| | ewright
| "Re(8):York T874R Sub Q674L to Honeywell RTH74" , posted Fri 22 Feb 15:35
I think I am about 1 year down on changing my thermostat as you did.
Did this 'X' tape off solve your installation? With X on, the blower seems to run all the time.
Do you have a 'single-stage' gas furnace with a heat pump like myself, and live in a cold climate?
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