We installed a new FA gas furnace, a Rheem 2 stage model. The contractor
installed a Honeywell digital, programmable Focus Pro TH6220 2-stage
thermostat.

We hate this Honeywell T-stat: When it comes on in the morning, the
temperature at the t-stat rises much more quickly than the room temperature.
Because the thermostat is usually 4 degrees ahead of the room temperature it
shuts the furnace off too quickly. The actual room temp may be 70 but the
t-stat reads 74. Since the t-stat was set to shut off at 74, the furnace
stops, although the room temp is only 70. It then keeps cycling on/off and
high/low until it reaches 74 degrees 2 hours later.

Honeywell has a good reputation. But, when I called them, the tech said that
it is normal for their t-stats to vary as much as 5 degrees from the actual
room temperature. He said this is normal for all Honeywell digital t-stats.
I told him this was ridiculous. The thermostat should show the correct temp
and it should not take 3 hours to bring my heat from 65 to 74. He said that
Honeywell digital t-stats do not have a heat anticipator.

Anyway, I was wondering if I can use my old single-stage thermostat with
this 2-stage furnace. I read somewhere that 2-stage furnaces have their own
circuit board and switch automatically from high to low heat, with or
without a 2-stage thermostat.

If this is correct, I could just pop in my old single-stage thermostat,
which worked fine with the old furnace. Why would anyone pay more for a two
stage thermostat for a 2-stage furnace, if the furnace will work fine with a
single stage t-stat?

Any input sincerely appreciated

--
Walter
www.rationality.net
-