Return to the Heating & Air Conditioning Forum | Post a Follow-Up

 o
Combining Thermostats - Wiring Help

Posted by rumrunner9 (My Page) on
Tue, Sep 17, 13 at 17:53

I'm trying to combine two old round style Honeywell thermostats into a new single Honeywell 7600D thermostat. One of the old thermostats controls the central forced air cooling, while the other old thermostat controls baseboard hydronic/boiler heat. All components are 24V. Each sheath has 3 wires only (R,G,W).

The heating system has 6 zones controlled by Honeywell V8043F1051 valves. I'm interested in only merging one of those zones with A/C into a single thermostat. The cooling is conventional compressor/air handler (no heat pump).

Current wiring is as follows:

Heat Thermostat to valves
R/RC --> red wire --> THTR
Y --> white wire --> not connected
W --> green wire --> TR

Cooling Thermostat to Compressor/Air handler
R/RC --> red wire--> switch/power
Y --> white wire --> cooling
G --> green wire --> fan

On the Honeywell 7600 thermostat can I connect as follows?
From heat:
red wire --> R
white wire --> leave unconnected
green wire --> W
From cooling:
red wire--> R
white wire --> Y
green wire --> G

In this case I'd be combining R to the same post which I'm assuming is not correct. Can I use the R from the cooling system to send current for heating (w) switch? Is there a way to wire these up to this or any other thermostat? Any guidance would be greatly appreciated.

Thanks!


Follow-Up Postings:

 o
RE: Combining Thermostats - Wiring Help

So would this thermostat wiring work?

From heat valve control wire:
red wire --> R (remove jumper)
white wire --> leave unconnected
green wire --> W
From cooling system wire:
red wire--> Rc (remove jumper)
white wire --> Y
green wire --> G


 o
RE: Combining Thermostats - Wiring Help

I assume you have separate transformers for heating and cooling systems. If that is the case then remove the jumper between the R and Rc terminals. Connect the red wire for heating to R and the red wire for cooling to Rc.

I think the rest of the wiring will work as long as you don't mix your similar color wires. You also have to program the thermostat for the correct heating and cooling system.


 o
RE: Combining Thermostats - Wiring Help

Mike,

Isn't that what rumrunner9 said? ;-)


 o
RE: Combining Thermostats - Wiring Help

Salti,

You are right. I didn't read his second post carefully.

At least we are in agreement.


 o Post a Follow-Up

Please Note: Only registered members are able to post messages to this forum.

    If you are a member, please log in.

    If you aren't yet a member, join now!


Return to the Heating & Air Conditioning Forum

Information about Posting

  • You must be logged in to post a message. Once you are logged in, a posting window will appear at the bottom of the messages. If you are not a member, please register for an account.
  • Please review our Rules of Play before posting.
  • Posting is a two-step process. Once you have composed your message, you will be taken to the preview page. You will then have a chance to review your post, make changes and upload photos.
  • After posting your message, you may need to refresh the forum page in order to see it.
  • Before posting copyrighted material, please read about Copyright and Fair Use.
  • We have a strict no-advertising policy!
  • If you would like to practice posting or uploading photos, please visit our Test forum.
  • If you need assistance, please Contact Us and we will be happy to help.


Learn more about in-text links on this page here