I have recently purchased a Honeywell wireless thermostat
(YTH6320R1015). Manual is here, page 4 is key:
I have split setup: A gas boiler in the basement (2-conductor thermostat
wire). My relatively modern Bryant AC unit is in the attic. I therefore
have two transformers. (For what it's worth, I've made sure they have
the same phase.)
I would like to control both systems with my thermostat. Honeywell tech
reps all agree that this must be possible, but give me contradictory
instructions. After several exchanges they seem to come to an agreement
that I might need a third transformer just to power the unit
independently from the transformers in my systems.
Does that make sense or could there be an easier solution!
Many many thanks in advance!
I don't see an issue. The "EIM" needs power (24 volt). It could be powered
by either transformer. Choose one. If you locate the EIM in the attic, power
the R and RC and C, from the air handler. Remove the existing jumper, which
is between R-RH-RC, from RH, which will be powered from the heating system.
The two wires go to RH and W O/B. If you want to install the EIM in the
basement, you can power the device from that transformer by removing the RC
from the jumper.
I have a Honeywell wireless set up. Like wise needs only one 24V source
because it is present all the time. Just hook up control leads from both
neating/cooling properly. My unit is about 5 years old never was any
trouble other than replacing batteries on the 'stat/xmtr.
**My mistake, you do have to power the unit from the cooling system. C and
R, with jumper to RC, powers the unit and the cooling. Remove the jumper
from RH. connect the Y and G from your cooling system as well. Then the 2
wires from the heating system just go to RH and W o/b, and it doesn't matter
what order these two go in
Thank you for all the responses.
May I confirm that I understand something correctly? The reason why I
CAN'T power the unit via the heating system is because it doesn't
provide a hot. The two present conductors are responsible for the relay
Exactly, typical heating system series 80, two wire, consists of a hot and a
return, but no common.It isn't so much that you can't do it using the
heating system's transformer, it's just that finding and accessing the
"common" for the 24 volt power supply can be difficult on the heating
system, where as on the cooling system it should be clearly defined
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