Help Needed with a Suburban Furnace and new Digital Thermostat

[AlmostGood]

My RV has a Suburban furnace with 2 blue control wires and old analog thermostat,
One blue went to the (R)red and the other blue wire went to the (W)white of my old thermostat.

I know the old thermostat handle the blue wires like switch, open/close.

But with my new digital thermostat the manual said connect the (W)white wire to the furnace and the (R)red to +12vdc.

So do I just connect one of the blue wires to the (W)white wire on the thermostat, which doesn't make sense?

Or do I need to add a relay or something.

Any help would be appreciated.

 

[Lynn1130]

Is there a help line or 800 number with the thermostat instructions? I am sure the help desk/customer service could probably help.

 

[jbeletti]

For powering your new thermostat, is it self-powered (batteries in it) or does it require external power?

My understanding of the Suburban furnace signal is...

One wire has constant +12 VDC on it and the other wire is the return back to the furnace to turn it on. That is to say, when those 2 wires are tied together, the furnace turns on. When they are broken, the furnace turns off.

In my current coach, that circuit closure is performed by a relay on the control board of my rearmost air conditioner. That said, I am considering using a separate thermostat to control only my furnace.

So back to your new thermostat, use a volt meter to determine which of those 2 control furnace wires is the constant "positive" 12 VDC wire. Connect that to the +12 VDC wire (red) of the thermostat. Connect the other furnace control (+12 VDC return) to the other thermostat wire (white).

The risk is all yours friend, but you asked, so that's how I'd try it. Please let us know how it works out and if it does work out well, please supply the brand and model of thermostat you used as I might want to copy you