Flaky Furnace Thermostat

BFL13 wrote:
The Suburban gas furnace Installation manual should explain which wires to use with the thermostat. ( Any link to the manual on Google? We could check that out.)

Of the three wires you need two with this Tstat AFAIK, but which two? IMO you can find out by touching them together.

Yes, the Tstat is just a switch and has its own battery to power it, so it does not matter if the wire ends on W and R are 12v.

Do you mean to go without the air conditioner and heat pump now, and just have the furnace? (Where we camp on the Island here we never need air conditioning, but YMMV)

From the tstat manual, the only thing that makes sense is to connect the red (+12 vdc) to the white (Furnace) via the additional tstat. But this didn't work and you seem sure that it doesn't matter that the 2nd tstat is made for a 24 vac system. Maybe that means that the tstat that I bought from Lowe's is bad?

No, I don't intend to go without the air conditioner and heat pump. Everything works fine now EXCEPT the OEM tstat (which I have replaced to no avail) randomly jumps to its default setting of 72 degrees ONLY when using the furnace. That is quite uncomfortable when it does it in the middle of the night after we have set it to 66 and the bedroom (being the highest place in the 5th-wheel) gets up to around 75 or so.

My plan has been to move the furnace control from the OEM tstat to a new "heat only" tstat. My plan is not to replace the OEM tstat.

(All of this is documented earlier on in this thread.)

As long as the outside temps are above 40, we get by with the heat pump and fireplace, but the furnace is our only option when dry camping.