My t-stat went bad on my HVAC unit so I bought a new one. Problem is, the two t-stats don't have the same letters where you wire it coding what it controls. I don't know if there are "typicals" when wiring a t-stat eg red is common white is cooling transformer etc. If there is a universal way that's cool and that would help greatly. If not then I would need to know how to distinguish what each wire is ran to then I can look at the owners book to see how to wire it in. Thanks in advance for your help.
An expert who has achieved level 2 by getting 100 points
An expert that got 10 achievements.
An expert that got 5 achievements.
An expert that has over 500 points.
Re: wiring in a new thermostat
On the usual 24v gas heat and cool system, the red is the 24v, or power from the transformer, the white is the heat, the green is the fan (the ON setting on the thermostat not the auto) and the cool is either yellow or blue. You can connect the red to rh or rc, if the new thermostat has this, just put a jumper wire between them. If your new thermostat has a c and o connections, you may have the wrong type.
- If you need clarification, ask it in the comment box above.
- Better answers use proper spelling and grammar.
- Provide details, support with references or personal experience.
Tell us some more! Your answer needs to include more details to help people.You can't post answers that contain an email address.Please enter a valid email address.The email address entered is already associated to an account.Login to postPlease use English characters only.
Tip: The max point reward for answering a question is 15.
The terminals on the old stat should be basically the same as on the new stat...with a couple exceptions anyway. Note the color of wire on each terminal before removing them and reconnect to the new stat on the same terminals. 8 wires typically indicate a heat pump, so in the configuration menu you'll have to tell it whether to energize the O terminal in cool or not. If you have individual wires on Rc and Rh terminals, you must remove the factory jumper between those two terminals on the new stat. If not, you'll burn out one of the two control transformers or possibly damage your new stat.
In the configuration menu, you'll have to tell it whether its a gas furnace or electric furnace, select the way the fan operates and possibly limit the cycles per hour on both heat and cool modes. There's a lot of subtle entries that need to be done to 'tailor' the new stat to your likings also.
I think it would be best to rely on someone thats a bit familiar with HVAC to change out your stat for you..... as once it is changed, all possible functions of the stat need to be verified as correct in operation.
First things first. What type of system? Heat only, boiler or furnace? Central cooling. Do NOT take wires off the old thermostat yet, or mark the color wire, to the terminal letter. Most times W,Y,G,R, terminals and maybe even a C terminal.
Your new thermostat should have the same letters. Sometimes they mix up color wire with terminal letters...... example (yellow wire to w terminal) Also turn off power to equipment it is controlling. It is not high volts but you can short out the transformer. Hook uo wire color to same letter terminal on old stat, to new stat. Thats it.
He needs to put the old stat back on...... The old stat is a Millvolt stat and the new Digital ones won't work. And I don't know if they make a digital for Millvolt.... The old floor furnaces used a power pile like a oversize thermocouple for the power to operate the gas valve.
Remove the cover to the thermostat to get to the control wires. Now remove the red wire from the stat. If it shuts off, the stat is bad. If it continues to run, the 24 volt hot wire from the stat to the unit is touching the cooling or heating wire somewhere from the stat to the control section of the unit. You can also disconnect the stat wires at the unit to prove this. You will need to pull a new set of stat wires to your unit, or if you have a extra wire not used , find the bare one that is touching, and use the spare wire in its place. Shastalaker7 A/C, & Heating Contractor
The red does go to RC, but the yellow should go to the W terminal, in HVAC W=heat Y=Cool, so aslong as the same wire is on RC on the t-stat, and RC on the unit, and same wire to the W on the t-stat as to W on the unit it should work!
If unit worked before you tryed changing t-stat then its possible the t-stat wires are shorting each other out.take t-stat back off cut back wires a good 6 to 10 inches or if you dont have that much wire to play with just cut back as far as you can and make sure there is no bare wire touching each other ,then just to test unit to make sure its working ok twist yell.,red,green together this should bring both units on and should blow cold.if this works up to this point on the new stat read directions closely there might be a jumper wire in the stat that needs connected usually from y1 to w1 you would install a jumper wire .see if this helps if not write back i have 1 other solution.i hope this helps
On the Goodman control panel each wire is marked (on the PCB board) Y, R, B, W, Br etc. These should also be letters next to the screws for the wires on the thermostat. match the letters/colors to both sides.