Opus007
Oct 9, 2012, 11:55 AM
I live in Ottawa, Ontario. I bought a brand new house 12 years ago. It is equipped with a high-efficiency gas-fired furnace with a tubular heat exchanger. The wiring module is a Honeywell THP9045 and it has five terminals: R, C, G, Y and K. The original thermostat was a programmable Honeywell T8132A. There are four wires coming out of the wall; they were connected to terminals W, Y, G, and R/RC. About two years ago, as part of a free program, an Ottawa Hydro technician replaced that thermostat with a Honeywell PeakSaver model T2060F. The four wires are now connected to terminals C, W, K and R/RC. Everything works great. But here's my issue.
I want to buy the new Nest thermostat. I contacted the company and described my current system in detail. They were puzzled by that K terminal and because of that they cannot guarantee that the Nest unit will be compatible with my system. I search the web for an answer and found a post (of unconfirmed reliability) stating that the K wire can simply be ignored.
If that is any help, here's a quote from the THP9045 wiring module manual: "The K terminal on the thermostat can be used to operate both the fan and compressor on a single wire, and the module is designed to receive the signal from the K terminal, split that signal and reroute it to operate the compressor, and/or fan for normal operation."
Also, when I provided Nest with my wiring configuration, they replied: "It really depends on what that K wire does, if your system can operate without it maybe the Nest will work but we would need to find out what it does first."
Can someone out there shed some light on this? My field of expertise is light-years away from HVAC. Thanks in advance!
Daniel
I want to buy the new Nest thermostat. I contacted the company and described my current system in detail. They were puzzled by that K terminal and because of that they cannot guarantee that the Nest unit will be compatible with my system. I search the web for an answer and found a post (of unconfirmed reliability) stating that the K wire can simply be ignored.
If that is any help, here's a quote from the THP9045 wiring module manual: "The K terminal on the thermostat can be used to operate both the fan and compressor on a single wire, and the module is designed to receive the signal from the K terminal, split that signal and reroute it to operate the compressor, and/or fan for normal operation."
Also, when I provided Nest with my wiring configuration, they replied: "It really depends on what that K wire does, if your system can operate without it maybe the Nest will work but we would need to find out what it does first."
Can someone out there shed some light on this? My field of expertise is light-years away from HVAC. Thanks in advance!
Daniel