When we purchased our house there were two separate thermostats - one for heating (a honeywell mercury - a red and white wire) and one for cooling (a LIPA Edge EM/ Thermostat - four wires - white, blue, green and red). We have gas and central A/C.

I purchased the Honeywell Vision Pro 8000 (TH811OU1003) to run both systems off one thermostat - hearing many great things about this thermostat. I am having trouble getting the A/C to work. The heat works. In my attic coming off my central air unit the wires are connected as seen below:

RH - empty
RC - Red wire and a jumper to a 24VAC
C - Blue wire
Y - white wire
G - green wire
W - empty
Y2 -empty
W2 -empty
H/A - empty
B - empty
O - empty
24VAC - jumpered to RC (see above)

How do I run the wires in the back of the new thermostat (what goes where)? Do I need a jumper? Do I need to reprogram the thermostat?

Are all 6 wires available at the new thermostat? If it requires a connection to the transformer at the C terminal to power it, you will need 5 wires. See the thermostat wiring section in the sticky at the top of the forum. You can't have hot and common at the thermostat plus heat, cool, and fan. If you must get by with 4 wires, you could leave the G at the thermostat empty, and connect the yellow wire to Y at the thermostat and Y and G at the furnace. That would give you heat and cool, but not fan. The thermostat would also need to be in the correct mode for your system.

You need the red wire connected to both RH and RC

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Originally Posted by jreingold

When we purchased our house there were two separate thermostats - one for heating (a honeywell mercury - a red and white wire) and one for cooling (a LIPA Edge EM/ Thermostat - four wires - white, blue, green and red). We have gas and central A/C.

I purchased the Honeywell Vision Pro 8000 (TH811OU1003) to run both systems off of one thermostat - hearing many great things about this thermostat. I am having trouble getting the A/C to work. The heat works. In my attic coming off my central air unit the wires are connected as seen below:

RH - empty
RC - Red wire and a jumper to a 24VAC
C - Blue wire
Y - white wire
G - green wire
W - empty
Y2 -empty
W2 -empty
H/A - empty
B - empty
O - empty
24VAC - jumpered to RC (see above)

How do I run the wires in the back of the new thermostat (what goes where)? Do I need a jumper? Do I need to reprogram the thermostat?

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Your close Remove the jumper from RC and RH if you have one, the two wires from the heating system will go to RH and W. You have a two transformer system. Red to RH and white to W. Make sure to set the thermostat up for Gas and or Electric heat but not Heat-pump. Good Luck

If this was a 2 transformer system, which I'm pretty sure it was. If you tried to run them with Rc and Rh jumpered you probably burnt out a transformer.