((Wiring)) Ruud T874R Q674L to Honeywell 7500 - http://www.hvacmechanic.com/ Forums

Original message

cjones002

70.119.28.166

"((Wiring)) Ruud T874R Q674L to Honeywell 7400" , posted Mon 18 Aug 11:49:

Hello there. First of all, is this configuration accurate for a 2 stage? If so, do I need a jumper from the AUX to the E?

This is what I configured:

Y -> Y yellow wire)
G -> G (green wire
R -> RC&R (red wire)
B -> C (blue wire)
O -> O/B (orange wire)
X -> E (black wire)
L -> L (brown wire)
W2&E -> W2 (one white wire connected both originally)

I appreciate the help!

0170 set at 7
0190 set at 0

Thanks
Chris

[this message was edited by cjones002 on Mon 18 Aug 16:23]

Replies:

Houston204

98.196.66.53

"Re(1):((Wiring)) Ruud T874R Q674L to Honeywel" , posted Mon 18 Aug 18:57

Post the numbers after Q674L ????

Honeywell has about 12 subbases in that series.

Are you sure every wire was in use before?

Did you write down the old terminal = color combination or get that combo from the web?

"Tip of the Day" Remember to remove power first.

cjones002

70.119.28.166

"Re(2):((Wiring)) Ruud T874R Q674L to Honeywel" , posted Mon 18 Aug 19:50

The numbers are Q674L 1504-8602. Yes, every wire was used before as listed above. The original color combination is the exact combo that was used.

Thanks
Chris

Houston204

98.196.66.53

"Re(3):((Wiring)) Ruud T874R Q674L to Honeywel" , posted Mon 18 Aug 20:49

O is reversing valve to cool. (O/B)
B is reversing valve to heat. (O/B)
X is common (C) This should be verified at your fancoil but I'm confident that this is the case.

The new stat demands that you choose O or B.

Very few systems use both the O and B terminal.
The EWG zone system uses both the O and B terminals, but you would have at least 2 stats connected to one system...

Rheem and Ruud had a low ambient control that did this...

Coleman had a package unit that used both...

These were the only times that I have seen The O and B terminals both in use. It is usually B for Rheem, Ruud and Weatherking and O for every other brand.

Coleman uses the O terminal, I checked while at Johnstone (a Coleman dealer).

"Tip of the Day" Remember to remove power first.

cjones002

70.119.28.166

"Re(4):((Wiring)) Ruud T874R Q674L to Honeywel" , posted Mon 18 Aug 22:07

Well, strangely enough, my a/c seems to be working perfectly well. No apparent noises or issues. I was just making sure about the wiring just in case. Do I need to rewire it anyway?

However, I noticed a little tiny note that states: "caution "B" or "O" terminals: checkoutdoor units diagram. We have changed the wiring on selected units".

Perhaps is this why it is working?

Thanks
Chris

Houston204

98.196.66.53

"Re(5):((Wiring)) Ruud T874R Q674L to Honeywel" , posted Mon 18 Aug 22:43

If you indeed have common wired to E, it will pop a fuse or damage your transformer when you call for emergency heat.

You also risk running the heat strips with any demand.

I would remove the panel to your fancoil and find out which color wire(s) is connected to C.

I would expect 190 to be 1 if the outdoor unit is a Ruud.
Where was this note?

The decision is yours.

"Tip of the Day" Remember to remove power first.

cjones002

70.119.28.166

"Re(6):((Wiring)) Ruud T874R Q674L to Honeywel" , posted Tue 19 Aug 11:25

Okay, I do believe that black is the common. This unit was installed in 1976 and electric heat parts were added in 1995 as hand written on unit. Thermostat rewired:
X (black)-> C
B (blue) -> O/B
What is done with O wire? Tape it off?

Also, the tiny note was placed on the thermostat panel itself.

190 set to 1.

Outdoor unit is a 2 year old Ruud that was recently replaced.

Thanks
Chris

Houston204

98.196.66.53

"Re(7):((Wiring)) Ruud T874R Q674L to Honeywel" , posted Thu 21 Aug 20:51

"Tip of the Day" Remember to remove power first.