Friends,

Okay here it is:

I have a Carrier Weathermaker 8000 (installed in 2000), and it has a standard thermostat. I want to put in a programmable thermostat with it, but... first I need to find out if my furnace is a multistage or not. Is the Carrier Weathermaker 8000 multistage? I know that it is 2 speed, but is that the same as multistage?

If it is, how does it do so with only one Y wire and one W wire (though the marking on the terminal, in the thermostat for each is Y/Y2 and W/W1)?

Detail of all Wires terminated in inside my Carrier (non-programmable) thermostat, the wires are

Do Not Use
R (Red Wire Connected)
Y/Y2 (Single Yellow Wire Connected
G (Green Wire Connected)
W/W1 (Single White Wire Connected)
C (Black Wire Connected)

The blue, orange and brown wires are just pushed back into the wall.

Now, I just bought a Honeywell Single Stage Programmable Thermostat (RTH6300B1056 - Took back the Hunter). Everything seemed to work okay, except that the furnace fan wasn't pushing as much air as it normally does. It made me think that my furnace was possibly a multi-stage unit.

If I get the RTH7500D (which is made for multistage units), I don't have two Y wires nor do I have two W wires. Does the thermostat (says Carrier on the outside) have some sort of built-in ability to change the fan speed, that I don't need two Y/W wires or am I just SOL and I can't use a programmable (Do it yourself) setup?

Is there some other thermostat that will be programmable/multistage with the existing wires I have?

Thanks so much,
Eric

My Bryant system is 2 stage controlled by a basic 4 wire thermostat. The little switches inside it are set so the furnace decides which stage to fire. If you have a multistage system set up the same way, I would leave well enough alone and install the new thermostat as a basic 4 wire or 4 wire plus common if needed.

labman,

Thanks for the reply.

I had it setup that way with the Honeywell programmable 5-2 (RTH6300B1056), and the furnace wasn't pushing as much air as with the old thermostat (I didn't believe it myself so I simply re-installed the old to check.

Do you think I should do the Honeywell RTH7500D (with multi-stage) capable?

Thanks,
Eric

If it will work in a single stage mode, go with it.

?? Even if my system won't blow hard as it used to? Will it still manage to keep my house warm, and do it efficiently? Today in Indianapolis it's like 18 degrees.