Not many in the US, vs our Canadian friend's. That's another mistake.
Another mistake is to imagine that it takes less heat energy to humidify
a house than the energy saved by turning the thermostat down 2 F for equal
comfort. That only works if you live in an airtight house without much
insulation, eg an old oil tank in Barrow, Alaska :-)
Winter humidification typically consumes 10X more energy than it "saves."
Nick (again repeating obvious truths to people who will not listen.)
Hello Again to all,
After doing a bit of detective work, here's what additional information
that I've gathered:
The cenral air conditioner is a Ducane AC10B30, the thermostat is a
White-Rogers thermostat (model 1F80-261), the furnace is a Keeprite
high efficiency central forced air furnace (model PS-90), and the
humidistat is a Broan knob-type switch which controls the furnace's
blower through an air flow pressure switch.
The R, W, G, and Y terminals of the thermostat is connected to the R,
W, G, and Y terminals on the control board of the furnace,
The humidistat pressure switch is connected to the R and G terminals of
the control board on the furnace.
And the central A/C is connected to the Y and C terminals of the
As shown below, disregard the periods, they're just used to line up the
letters (sorry for the poor diagram):
Whenever the humidistat turns on, it is turning on the A/C as well. It
seems to be backfeeding the Y terminal through the thermostat (the Y
and G terminals of the thermostat seem to be internally jumpered
together from my ohmmeter readings).
Any more suggestions on this problem?
Jumping into to this late, but when the thermostat fan switch is set to
"Auto" there is a jumper inside the thermostat, that jumps 'G' (which
starts the furnace fan) to 'Y' (which starts the outdoor condensing
You will have to add a relay.
Hopefully I am not double posting.
KJ, when you say the 120V control connections, it sounds as if you are
talking about the line voltage to run a humidifier.
It sounds to me like 'Winterpeg' is not running a humidifier but trying
to reduce high winter humidity by ventilating with cold dry air. Its a
Canadian thing, tight homes and high winter humidity.
I think the installers wired it up so on a rise in humidity, it would
start his fan. Probably a fresh air intake to the return. Sucking in
cold dry air will bring humidity down so you do not get window
Except with the fan switch in "Auto" position, everytime he puts 24
volts to G, to start fan, he is also starting the condensing unit.
Setting the fan switch to 'Auto' is a switch inside the thermostat that
'jumps' Y to G. So the dehumiditat sends 24 volts to G on the furnace
but the power goes back to the stat, through the jumper to Y and starts
the AC in the winter.
Have the dehumidistat 'take' power from R. On a rise in indoor
humidity, it will power a coil of a 24 volt DPDT relay. The return from
the relay coil goes to C.
One set of NORMALLY OPEN (NO) contacts will close to send power to G
and will start your furnace fan. A set of NORMALLY OPEN (NC) contacts
will open to break Y and prevent your outdoor condensing unit from
You will need to add an on/off switch between R and the dehumidistat.
The switch is turned ON in the winter and OFF in the summer. Otherwise
the dehumidistat will prevent the air conditioner from coming on in the
summer. You need to remember to flick the switch back on the next
You may have to look and see if there is some motorized damper that
opens to let fresh air into your return air duct work. You may need to
power that motor the same time you power G.
Sounds like you are in Manitoba. Call Ecco Heating Products and see if
they know some one with a brain to come over and wire this up for you.
Thanks for all your great responses.
Abby, you hit the nail on the head, in Manitoba, high humidity becomes
an issue in the wintertime due to the "tightness" of the house
...the relay solution sounds like it will do the job.
Peg, I grew up about 7 hours drive east of you. To figure out how cold
I would be 'tomorrow', I just looked at what Winnipeg was 'today' and
added 5 degrees.
HRV is really the way to go, have it cycle on/off with a rise in
humidity. Maybe even get a cheap one from Beaver Lumber (is it Ace now?
left Canada 7 years ago)
You can try the relay like I said, and maybe you only have to break
'Y'. Instead of a switch you could also set the dehumidistat up to max
like 80 in the summer so the damper never opened, and then set it back
down in winter. How low you set depends on how good your windows are.
Ecco Heating Products will know of someone who can fix you up, else buy
me a Westjet return ticket and I'll do it this summer when I go back
For the time being, open the breaker to the outside unit so it does not
run. After you rectify the problem and at least a day before you ever
run the Air conditioning, turn the power back on to the outdoor unit.
You need to let the crankcase heaters in the compressor heat back up
before you start it. Otherwise I would say to never shut the power off
to the outdoor unit.
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