I decided to replace my 6 year old digital thermostat (Honeywell), with a
new programmable thermostat (Hunter).

The wiring is the basic White,Yellow, Green, Red.

The new thermostat had the following connections:

G - RC - RH - Y/0 - W/B - Y1 (A jumper wire between RC & RH came
pre-installed).

I connected the wiring & ran the a/c, it worked fine.
I kicked on the heat, it ran fine & cycled off but, the flue purge motor
continued running after the furnace had shut off. (It never did this with
the old thermostat.). I had to shut off the motor with the rocker switch on
front of the furnace.
I double checked all connections & they were secure & correct.
I double checked that the switches on the back of the thermostat were set to
"STD" as opposed to "HP" & "HG" as opposed to "HE". I ran the furnace, same
thing, purge motor kept running.

I did some poking around on the net & came across several websites that said
to disconnect G, & if the motor continued to run, the problem was most
likely a stuck relay. I had an electrician look it over & he said he didn't
think it was a stuck relay & he suggested to re-connect the old Honeywell
thermostat & see if the motor continued to run.
It didn't.

I assumed I had a bad thermostat. I returned the Hunter & purchased a
Honeywell. I connected the new Honeywell, fired up the a/c, everything
worked fine. A few minutes later, I fired up the furnace, let it run, cycle
down & shut off...the purge motor continued to run.

Obviously, it wasn't the thermostat. I re-connected the old Honeywell, fired
up the furnace, let it run, cycle down & shut off, the purge motor also shut
off.

Can anyone shed some light on this. I'm not the most mechanical person but,
something that should be simple has me stumped.

Douger wrote:
I decided to replace my 6 year old digital thermostat (Honeywell), with a
new programmable thermostat (Hunter).

The wiring is the basic White,Yellow, Green, Red.

The new thermostat had the following connections:

G - RC - RH - Y/0 - W/B - Y1 (A jumper wire between RC& RH came
pre-installed).

I connected the wiring& ran the a/c, it worked fine.
I kicked on the heat, it ran fine& cycled off but, the flue purge motor
continued running after the furnace had shut off. (It never did this with
the old thermostat.). I had to shut off the motor with the rocker switch on
front of the furnace.
I double checked all connections& they were secure& correct.
I double checked that the switches on the back of the thermostat were set to
"STD" as opposed to "HP"& "HG" as opposed to "HE". I ran the furnace, same
thing, purge motor kept running.

I did some poking around on the net& came across several websites that said
to disconnect G,& if the motor continued to run, the problem was most
likely a stuck relay. I had an electrician look it over& he said he didn't
think it was a stuck relay& he suggested to re-connect the old Honeywell
thermostat& see if the motor continued to run.
It didn't.

I assumed I had a bad thermostat. I returned the Hunter& purchased a
Honeywell. I connected the new Honeywell, fired up the a/c, everything
worked fine. A few minutes later, I fired up the furnace, let it run, cycle
down& shut off...the purge motor continued to run.

Obviously, it wasn't the thermostat. I re-connected the old Honeywell, fired
up the furnace, let it run, cycle down& shut off, the purge motor also shut
off.

Can anyone shed some light on this. I'm not the most mechanical person but,
something that should be simple has me stumped.


Hi,
No trouble code from your furnace control board by way of blinking LED?

Douger,

Since it runs fine with the old thermostat, the problem has to be in
the new one. That's the only thing you've changed.

I recently switched to a six-wire, dual fuel (heat pump and gas forced
air) system from a standard three-wire one. The thermostat has a "set-
up" mode that controls a multitude of things (40+) as the system is
rather complicated. It is accessed by pressing a certain combination
of "buttons" on the display and then quickly gets rather cryptic (ie
code numbers and values). But, that should be covered in the manual
and I doubt you would miss it.

The other possibility is that you are getting the wrong kind of
thermostat (hence the six connections). Years ago when I did the same
thing I bought a programmable one that only had three connections.
However, I didn't have a purge motor as it was an 80% job. Maybe my
new system has one, as it is 96% efficient and I just don't realize
it.

Good luck.

dss

"dss" wrote in message
...
Douger,

Since it runs fine with the old thermostat, the problem has to be in
the new one. That's the only thing you've changed.

Yes, I came to the same conclusion.

I've had the old Honeywell connected & it works fine, save for the sticky
"down" button; which is why I needed to replace it to begin with. It's stuck
@ 71 degrees.

I guess I'll look for a thermostat with just the G - R - W - Y wires but,
it's hard to see the connections without opening the package.

Douger,

If you get one that says it doesn't work with heat pumps or multi-
stage furnaces it should just need the three wires. They are also
usually cheaper. If you have a multi-stage you may be hosed.

I'll probably be doing the same thing for my daughter when she buys a
new house, so let us know how it turns out.

dss

"dss" wrote in message
...
Douger,

If you get one that says it doesn't work with heat pumps or multi-
stage furnaces it should just need the three wires. They are also
usually cheaper. If you have a multi-stage you may be hosed.

I'll probably be doing the same thing for my daughter when she buys a
new house, so let us know how it turns out.

dss

I'm not following you.
Are you saying I only need to connect 3 of the wires?

On Oct 22, 5:01*pm, "Douger" wrote:
"dss" wrote in message

...

Douger,

If you get one that says it doesn't work with heat pumps or multi-
stage furnaces it should just need the three wires. They are also
usually cheaper. *If you have a multi-stage you may be hosed.

I'll probably be doing the same thing for my daughter when she buys a
new house, so let us know how it turns out.

dss

I'm not following you.
Are you saying I only need to connect 3 of the wires?

Typically you have 4 wires:

hot wire, ie current source
heat on
A/C on
fan on/off, ie so you can have the blower run all the time or only
when heat or AC makes it go on.

Your problem is very strange, because per above, nothing from the
thermostat should have an effect on the inducer fan. That is
controlled by the furnace contoller/logic board. The thermostat justs
connects the hot wire to the heat wire to tell the furnace to fire
up. From there, the furnace controller starts the inducer, turns on
the gas, ignites it, starts the blower, etc. When the thermostat
opens, the furnace starts the shutdown sequence.

How long have you let it just sit there with the inducer running after
the furnace shuts off? Does it just keep running indefinitely?

The only thing I can possibly think of is I think some thermostats
steal small amounts of power from the circuit to keep batteries
charged. I don't think most of them do that, but believe some do.
It could be that having that small current flow even when the heat
circuit is essentially open is somehow disrupting the controller in
the furnace. But that seems a long shot.

Might be time to get a HVAC pro.

Douger,

Forget my mention of three wires. I'm probably not remembering
correctly as it was 20 years ago when I installed the programmable
thermostat. The old one was one of the round analog models.

At the big box stores they have thermostats that work with heat pumps
and multi-stage furnaces, and those that don't. It's usually noted on
the back of the package in small print. I think you need the one that
can't control a heat pump. The simpler one should not have six
connections on the back. Although, from your first post it sounds like
you can get around that by setting some switches.

It's probably time to ask the people at Honeywell what thermostat you
should use to replace your existing model. The old one is either doing
something or not doing something that your replacements are not
replicating.

Good luck. Something this simple shouldn't be so difficult.

dss