[HVAC] Thermostat C wire on Honeywell RET97B5D Wireless
Schematic for the AC /Heat control
I purchased a Honeywell RET97B5D thermostat and i have a problem with the lack of the C" wire. Currently my thermostat has 4 wires. I measured between RH (red) and the each of the other wires and i measure about 29 vots AC. (Based on the 29, i am not sure if i can use any of these wires as the C wire.
I checked my heat and AC control and i noticed that the C terminal is hooked up to the condenser so i can not do who Honeywell recommends which is to use the G (green) as the future C. I currently have 2 zones and i would like to the replace the current thermostats with wifi Honeywell RET97B5D can someone help me in guiding me what to do with the missing C wire? Thanks John Medeiros
There is a way to add a C wire with just a regular power outlet. I have not tried this, but was researching options after my Nest was not compatible with a new HVAC system I had installed. Was considering going with a Honeywell but decided to just stick with the Talking Thermostat that the HVAC company installed.
These types of online instructions can be helpful for those with some HVAC wiring knowledge, but the uninitiated invariably only see a jumble of wires no matter what. Many will want to try to do this work on their own and we get those guys/gals asking for help with their personal rats nest, since each one is a little different. -- ~Help Find a Cure for Cancer~ ~Proud Member of Team Discovery ~
I can't believe that relinquishing fan control has become an acceptable solution just to install a fancy thermostat. I would be 100% unwilling to settle for such a hoakey solution.
Thermostat companies should be ashamed at providing such a ridiculous "solution" just to keep people from returning their over-priced product. Why don't they incorporate a multiplex solution into the thermostat? Why don't they put a plain English notice on the box that it will require a 5 wire cable?
Run a new t-stat wire or buy a thermostat wire multiplexer. -- If someone refers to herself / himself as a "guru", they probably aren't.
I agree 100 percent. The fan option is to valuable to give up just for an overpriced fancy thermostat. When I upgraded my Heatpump system 2 years ago I had them change out my digital programmable thermostat and install a plain digital one. We never used the programmable as we just keep the same temp all the time.
However sometimes we do run the fan on manual mode and to not have that would be a problem.
there is a simple solution but people seem to be too lazy to do this, its called pulling a new wire through. if your gonna wanna use a high end thermostat, u might as well pull an 18-5 or better yet 18-8 wire, your wire looks too inadequate for thermostat, it looks kinda thin.
The Nest can run off of a 4 wire system without a C wire on most furnaces - they charge their battery whenever the fan is powered on.
Otherwise, you're either running a new cable with enough leads for a C wire from the furnace, running a 24V AC adapter's output to the thermostat, or using one of those add-a-wire adapters along with your existing wiring.
These types of online instructions can be helpful for those with some HVAC wiring knowledge, but the uninitiated invariably only see a jumble of wires no matter what. Many will want to try to do this work on their own and we get those guys/gals asking for help with their personal rats nest, since each one is a little different.
Let's just agree to disagree and leave it at that, okay?
Thanks to all that have provided input. So far, i followed Honeywell recommendations which is (at the thermostat ..G goes to C & @ the furnace ,,g-c and the jumper)., but it doesn't fully work. Somehow the heat works but the AC only stays on for a couple minutes and then it shuts off. It appears that the voltage isn't strong enough. If am run the 5 wire conductor, where does the 5 wires go at the furnace? I am getting ready to undo what i did, please advise if you can Thanks John