2-stage thermostat

[avm]

I am replacing my old gas furnace with a new 2-stage furnace. The contractor tells me that I will have to replace my old thermostat with a new 2-stage thermostat and I should get an electrician to do it. My questions:

1. Do I have to replace my old thermostat? I do have a single stage central A/C unit.

2. Does the 2-stage thermostat use the same wiring used by my old single stage thermostat?

3. Do I really need an electricial to do the job?

[Senior Tech]

Yes, you really should replace it.

No, you will need more wires.

I would think the contractor could do it? We never use an electrician for low voltage although it could be required in the area you live.

[mayguy]

Two stage t-stat will make your furnace a TRUE two stage furnace, and will provide better COMFORT.

So, yes, you should replace the t-stat.

If there is an extra wire tucked into the wall, then a new wire is not needed. The installing dealer should be able to tell you this.

Why can't your dealer do the low voltage?

[smokin68]

1. yes, for best performance.
2. It can if the original t-stat had extra wires pulled, i.e. an 8 wire 18 gauge conductor.
3. nowhere that I know of for low voltage, your installer should do this, if they can't seek someone that can.

[beenthere]

Originally posted by smokin68
1. yes, for best performance.
2. It can if the original t-stat had extra wires pulled, i.e. an 8 wire 18 gauge conductor.
3. nowhere that I know of for low voltage, your installer should do this, if they can't seek someone that can.

On a post in pro tech forum, someone just posted that they must have an electrical license to run low voltage wiring in their area by local code.

[vzcooler]

Alot of new furnaces, do go both ways, depending on the make heil tempstar arcoaire, give you the option, you do have to move dip switch on sc1 on the circuit board to the off position, it will purge, ignitor comes on,pilot lights, burner comes on at low gas pressure, then runs to time out @ 12 to 15 minutes depending on model then goes to high fire at full pressure, these units even know they are now man by utc , are a pretty good unit very versitile you didnt mention what kind it was or did i miss that parts,

[avm]

I am thinking of the Goodman GMV8 series 2-stage variable speed furnace, which is a fairly new product for Goodman.

[BaldLoonie]

The great benefit of a 2 stage furnace in a cold climate is LONG run times on low. If you are in the car on a cold day, you never turn the heat OFF, you throttle it back to a low setting for gentle heat. A 2 stage furnace with 2 stage stat will do just that. Run long periods on low, switching to high only if necessary. Not possible with a timer. I put my furnace in during a very cold spell and didn't have the 2 stage stat the first few days. That poor furnace was all over the place, low for 10, high for a couple then off. Repeatedly all day long. With the 2 stage stat, low for long periods then cycling off.

[avm]

If I use a wireless 2-stage thermostat, like the Totaline 30403, would it make it simpler to install? Does any one have any experience with a wireless thermostat?

[amickracing]

Wireless possibly could make things easier, providing it's tough to pull new wire for a convential stat. Could be over kill.... but then again a wise man once said, Anything worth doing is worth doing in excess!

I've never used a wireless stat before, but I can't say I've heard bad things about them either.