On Oct 24, 9:41*am, "
wrote:
On Oct 23, 3:19*pm, Tony Hwang wrote:





Nate Nagel wrote:
Given this wiring diagram

http://www.patriot-supply.com/files/...atic%20(90-225....

there's no connection for a humidifier, is there...?

My brain is working slowly this morning and I'm annoyed at having to
search all over the place for part nos. etc.

this is for a Rheem RGEB-06EC-FS furnace which apparently uses a
47-22481-81 fan control board. The "Honeywell S-890G" has been replaced
at some point with a S8910U. The schematic on the actual cover is
slightly different from the PDF and labels the blower control as a
"Honeywell ST780C" (or maybe 788? I took a photo of it and reinstalled;
photo is not as clear as it could be) Also "IDM board" is not present on
schematic on cover.

thanks

nate

Hi,
No big deal as long as you remember humidifier comes on when blower
runs and if humidistat calls for humidity.(so called AND logic)
And is depending on what type of humidifier.- Hide quoted text -

- Show quoted text -

Actually, wired the way he proposes, the humidifier will come
on as soon as the thermostat calls for heat, ie before it's even
ignited or the blower has started. *I assume by blower we're
talking about the air handler, not the inducer.

Sorry, yes, I was referring to the big air handler blower, not the
inducer fan... I suppose it's possible to interlock it with that, but
I'm not sure why you'd want to.


I had my previous furnace done like that and it worked
perfectly. *I think there is even some advantage to doing
it that way, as it cuts off the humidifier as soon as the call
for heat ends. *The blower then runs another couple mins
giving it a little more time to take away some of the moisture
left in the media, instead of having it sit in the furnace plenum.

Actually if I got real fancy I could keep the humidifier blower
running after the water valve shuts off, but that might violate the
KISS principle

The real reason that I'm going through all this effort is that I had
to do similar work at my old house after one day I found that either
the A/C was running or the thermostat had been set to "Fan On" (I
don't remember which it was right now, but the heat was definitely not
on) and due to the A/C having been added much later than the
humidifier, no thought was given to interlocking everything so that
the humidifier wouldn't run when the A/C was running, only when there
was a heat call and the AH blower was running. So there was water
running straight through the humidifier and down the drain, which is
kind of wasteful and pointless. However, once I did my research, in
that case it was fairly easy as the humidifier was straight 120VAC and
the furnace control board had a 120VAC "HUM" terminal - for reasons I
don't understand, the receptacle for the humidifier was wired to a
120VAC terminal on the board that was given for an electrostatic air
filter instead of the "HUM" terminal (the air filter actually used a
DP switch to turn it on so that terminal was unused) in that case the
actual fix took about 1% of the time it took to figure it out. Once I
understood what was going on it was kind of a head smacker

SO... in the interest of getting this place set up so that everything
happens automagically, should someone set the thermostat to "auto,"
I'm trying to replicate that sequence but with different components...

nate