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Phil, Mechanical Engineer
Category: HVAC
Satisfied Customers: 6022
Experience:  Retired HVAC/ Electrical & Boiler contractor. Industrial
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I'm trying to replace my thermostat. From my old thermostat

Customer Question

Hi, I'm trying to replace my thermostat. From my old thermostat the wires were connected to G, W, O, RH. My new thermostat Honeywell focus pro 6000 (TH6110D1021)... it has G, W (o/b under it but same port), C, Y, R, RC. My problem is where do I connect the O wire in my new thermostat?
Submitted: 2 years ago.
Category: HVAC
Expert:  Brian HVAC Guy replied 2 years ago.
Hi I'm Brian and I'm here to help! I'm sure I can help with that! You say: "From my old thermostat the wires were connected to G, W, O, RH". Were those the ONLY wires connected to your old thermostat? Was there a connection at Y on your old thermostat? Can you please tell me what type of system you have and are trying to hook up the Honeywell to? e.g. gas furnace, ground source heat pump, boiler with zone control, etc...? Thanks, -Brian
Customer: replied 2 years ago.
Yes there's a connection to Y but no wire was connected to it and we have gas furnace
Expert:  Brian HVAC Guy replied 2 years ago.
So you have a gas furnace with NO cooling? This is a heat only application?
Customer: replied 2 years ago.
We have a central cooling system. A few months ago there was something wrong with our heat. It wasn't turning off. The fan kept going. We called an HVAC tech to come in. He said it was our thermostat (only 3 years old) so he replaced it with theirs it looked like an older version of our 3y/o thermostat. Anyway, ever since he changed it to their thermostat the cool option doesn't work. So, I bought a new thermostat which is the Honeywell brand.
The thermostat that came with the house is an Emerson digital led brand. The one he replaced it is not even led display.
Expert:  Brian HVAC Guy replied 2 years ago.
Ok, thanks for that additional info! Since there is currently no connection at Y on your existing thermostat, that would explain why the cooling is not working. Can you tell me what color wire is(was) attached to the O terminal please? Do you by chance have the ability to take a digital picture of your old thermostat and the wiring attached to it, and upload them here using either the paperclip icon or the Attach Files button in your reply dialog box? Basically we have to figure out where and what color the wire that should be wired to the Y terminal is. Thanks, -Brian
Customer: replied 2 years ago.
Hi, I don't see any attached or paper clip button. Just reply to expert button.
Expert:  Brian HVAC Guy replied 2 years ago.
Once you click the button to reply to me, in the window that opens (depending on which type window opens) there will either be 1) a toolbar for editing text and such with a paperclip icon as one of the buttons or 2) a button in the lower left of the the dialog box labeled "Attach Files". Click whichever one of those you see and then use the browse button to navigate to the file on your computer and select "open". This is similar to attaching a file in an email. Thanks, -Brian