I was thinking of the more complicated relay route, but how about breaking
the tied common side of the humidifier and the outside A/C unit with the
cutoff switch? Would that work?
The only helpful comment from the "professionals" at alt.hvac, one said that
the furnace condensate is acidic and per some codes, the pump should always
shut the furnace down. Since I am away usually only a few days, maybe the
risk of frozen pipes is minimal.
--
Rick

"john williamson" wrote in message
...

Condensate pump wiring

Group: alt.home.repair Date: Sun, Oct 19, 2003, 2:03pm From:
(Rick)
I have a newer Rheem RGRA gas furnace with a Rheem A/C controlled by a
Honeywell T8600D thermostat, and an Aprilaire 760A humidifier. I would
like to use the condensate pump's cutoff switch to shut down the A/C and
the humidifier water supply, but not the furnace, to avoid a freeze
condition. How can I wire the system to work? The alt.hvac guys were
less than helpful. Thanks.
--
Rick
++++++++++++++++++

John wrote:

No problem Rick, but you will need to add a relay or two. if you are not
comfortable doing this I would advise getting help. Make sure the
additional relays are installed on a small chassis or enclosure so as
not to likely short any wires or connections. I am just telling you how
it can be done.

I can not remember if the 760A water solenoid is 120vac or 24vac. If it
is 24vac you can use one SPDT 24vac relay, here are the connections:

+ (hot) side of the 24vac transformer that will be going to RH and RC
of the thermostat will go to one side of the pump safety switch.
+ The other side of the safety switch will go to the coil of the 24vac
coil relay.
+ The other side of the relay coil will go to the common of the 24 vac
transformer.
+ The existing wire at the thermostat terminal (Y) will need to go to
the common or switching contact of the relay. A wire from the (NO)
contact will go where the previous wire went from (Y) to the
compressor. Confusing I know but you are just putting the wire at (Y)
through the contacts and then to the compressor.
+ Put one side of the 760A solenoid through the other (NO) contacts of
the relay.

* If the 760A Solenoid is 120vac, use two 24vac coil relays and
parallel the two coils. Use the second relay contacts (common) and (NO)
to break the solenoid. I don't like to mix low and high voltage on one
relay, also label second relay as having 120vac on contacts.

John Wiliamson