Programmable thermostat wiring questions

General topics about all things heating, ventilation, air conditioning and refrigeration.

Programmable thermostat wiring questions

Postby jbshaffer » Sun Apr 21, 2013 12:34 am

Hi all just purchased a Honeywell RTH6350 5/1 prpgrammable tstat - problem is when I get to the wiring stage it tells me that if I have the following wires on my old tstat to call a contractor/ I have a heat pump with a gas emergency back up when the heat pump isn't enough.
Old tstat is a Lennox model 21J7101 and the wires are as -
Y1 - red
R - blue
L - brown
t - white
C - yellow
W1 - 2 wires red and Orange are connected
O - black

New tstat connections on I have 2 rows one for conventional and one for heat pump
conventional connections are Y2 - W2 - G - W - Not used - Y - R - Rc

Heat Pump connections are L - E - AUX - G - OB - Not Used - Y - R- Rc

any idea where I connect the Y1 and the W1 on the new tstat?
Posts: 2
Joined: Sun Apr 21, 2013 12:21 am

- Programmable thermostat wiring questions

Postby Freon » Fri Apr 26, 2013 3:58 pm

Go to the gas furnace and tell us what colored wire coming from the thermostat is connected to what terminal on the control board. Also when posting, don't use dashes, slashes or question marks.
Most Valued Contributor
Posts: 1011
Joined: Sat Jun 18, 2011 11:26 am

- Programmable thermostat wiring questions

Postby jbshaffer » Sun Apr 28, 2013 12:18 am

Hi Freon - sorry for my delay - I called Honeywell and they told me the RTH6350 would not work with my system - so I purchased the recommended TH8320 much more than what I was looking for. Now I need wiring for this one?? Geez never thought change out would be this difficult.
Old stat was a Lennox - 21J7101 - heat pump with gas back up
I forgot to include one wire in my previous post - so here is the wiring on the old tstat
Terminal wire Color
Y1 Red
R Blue
L Brown
T White
C Yellow
W1 2 wires Red and Orange
O Black
G Green

The new Honeywell tstat model TH8320 U 1008 connections on the back are as follows
Y2 L E AUX(W2) S1 S2 RC R O/B (W) Y G C the terminals marked with ( are codes listed on the inside of the terminal panel. In other words there is an outside row that has the codes and an inside row that has codes - both look to be the same terminals.

There is a jumper on the RC and R terminal

Hope that helps -
Posts: 2
Joined: Sun Apr 21, 2013 12:21 am

Return to HVAC General Forum