honeywell 7400

brianb

connecting a honeywell 7400 to a rheem rbhb-25j21suea heatpump
old stat
yellow-y
blue-b
red-r
labeled x(looks pink could be brown)-x
green-g
white-w2
w2 jumped to e

dac122

What was the old tstat?

brianb

old stat honeywell with mercury
it says heat pump themostat
i can't find a number on it

dac122

What type of heating and cooling are we dealing with here: furnace, A/C only, Heat Pump, boiler, etc?

brianb

rheem heat pump

dac122

Here's what I think so far:
color old new
yellow y Y
red r R/RC (jumpered)
green g G
white w2 Aux/E (jumpered)

The other two wires b and x I cannot be sure of without knowing the old tstat model. My guess is one is the common/neutral (wire to C) and the other for your reversing valve (wire to O/B).

Under these circumstances I recommend a staged approach to wiring up. First get power to the tstat with R and common/neutral (try blue/b), and test. Next wire up G and test your fan is working. Next get your Aux heat to work. Finally wire up the reversing valve and test both heat and cool.

You also need to configure the RTH7400, so read the manual carefully.