Quote:
Originally Posted by rhythmtone
Awesome thank you for the reply! This is getting a little heavy it but makes total sense, I'm going to think on it for a little while - I don't really want to open the chassis of the furnace, if that's what's necessary to do this, but maybe.
My furnace does use that wiring diagram I posted, 2 for power (for the fan motor I'm sure) and 2 for control (both blue wires). If those "control wires" are connecting the ground, to activate the unit, as you say is most common, then there should be no voltage between them, I assume, but I will check with a meter.
I don't want to mess with the power wires to the unit, obviously, because I'm sure that it's designed to warm up and cool down with "independent" thermostat control, which is why it takes a while to shut off even when you've disconnected the control wires, but your explanation of the solenoid function is great. It's a 2006 Suburban propane furnace if that helps, but believe that they do have several possible wiring diagrams, so I don't know exactly how it's set up.
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I'm pretty sure the Fan control was only applicable to the AC fan, not furnace. To the best of my knowledge the furnace fan is a constant single speed.
But I did a little more exploring for easiest way to rewire to Tstat.
What seems best is to jumper the two furnace wires back to the tsta via existing leftover wires in the umbilical cord. Two wire nuts is all it takes.
DETAIL:
Reflecting on your comments, I decided to take another look at Tstat wiring options to see if it might be possible after all.
Took a better look at the wire interfaces to the Cool Cat unit interface in the alcove.
All 7 Tstat wires (now unused), the 2 Green furnace control wires and a Red and Black pair carrying 12Vdc (bonus) were all in the single umbilical cord plug at the roof end.
So, chopped the plug end off of the discarded Cool Cat unit and jumpered some wires together (wire nuts) and plugged it back into the cable where it was originally.
Jumpered one of the Green furnace wires to White the other Green furnace wire to Tan (one of the 7 unused wires traveling to the Stat location above the bed. In the new scheme Org, Blu, Yel, and Tan are unused. Use which ever you want. I chose Tan. The others have a color coded terminal location and though still unused, are more astheticaly logical).
Went to the Stat location and shorted the White and Tan together, furnace worked fine. (This is all that is needed to do furnace)
>>>>>>>>>>>>>>>>>>>
Wanting 12Vdc at stat for future tinkering; Jumpered the 12Vdc Red to stat Red/Wh and Black 12Vdc to Green.
The white and tan are all that is needed to employ the 2 wire Battery operated Heat only Tstats (such as a Honeywell TH1100DV1000).
But I saw the Honeywell RTH111B stat at Lowes for $22. Cheaper than a heat only at Amazon; and available immediately in store and it had an 8 wire terminal so we could land all the wires (even though unused) into the termainal (neat freak thing).
Removed jumper from Rh, Rc terminals, landed Tan on Rh and White on W (for furnace connection).
landed Red/Wh on Rc and Grn on "not used" terminal (just for future availability).
Being not certain how the stat manages the G (fan control logic (previous use of G in this new stat)) did not want the risk of the (now grounded) Green wire to end up switched to Rh or Rc which would wipe out a fuse; or worse. (Yeah, I know; tape and tuck. But wanted availability; and the there is the neat freak thing.)
Orange to O, Blue to B, and Yellow to Y (these were previously for Reversal valving and Cool activation.)(All now unused and "open" at the alcove end up above.)
Now stat (battery powered) handles furnace and 12Vdc is available at the Rc and Green wire terminals if ever needed/wanted.
As a side note, I think the original Dometic stat could still be used by powering the +7.5V terminal with the +12Vdc by putting a 1K resistor in series to drop the voltage to the 7Volt level needed.
Would need to tinker with this to confirm.
If pictures are wanted/needed let me know..
Cheers
Toad
... Mayby A better way..2 wire nuts; 4 if you want fancy
Linear Mode
