Question about Honeywell Programmable Thermostat Heater

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Mr. no tv 4 you

I have a wall T stat with 2 wires black and white I would like to hooK it up to a 7 day programable t stat. But were do I hook up the wires to. "W" "Y" "G" "R" or "RC" The furnace is a gas furnace.

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Re: Mr. no tv 4 you

Show me the steps (short ones) to get this Machine" working right!

Posted on Jan 16, 2008

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Re: Mr. no tv 4 you

Don't quite understand the first post.
W is white or heat
Y yellow is cool (or B for blue) either will do
R is red or 24v
RC is the same as R, unless you have separate transformers for heat and cool, place a jumper from the 2 R's
Your old wires, though are 1 white and 1 black, usually this indicates line voltage. 120v or a milli-volt @.750v. Either case, you have the wrong type of thermostat for this application.

Posted on Jan 10, 2008

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Bought new thermostat model ct87k but old Honeywell model I have was hook up by black and white wire not red and white , so how do I hook up.

The two wire Honeywell T87 and CT87 is nothing but a switch in a control circuit. Wire color is not important at all. What is important is the TERMINAL DESIGNATION those wires are hooked to. Soooo....take the wire off of the sub base of the old stat terminal marked 'R' and attach it to the new sub base terminal marked 'R' and so on. Wire COLOR means nothing at all in your case.

Oct 04, 2014 | Honeywell CT87K1004 Round Heat Only...

1 Answer

I just installed a new Honeywell thermostat on Saturday and it stays on for about 60 seconds and shuts off. I have the heater on 90 and it is 48 in my home. The heater does not kick on. What should I do?

Th e first thing I would recommend doing is to remove the cover from your thermostat and the three or four screws that secure base to the wall .Check to see that all wires are hooked to proper terminals. On most t-stats the R.c and Rh should have a jumper wire And red hooked to R.
To make sure you did not get a bad t-stat I would dissconnect all wiring from t-stat after noting how it's wired now. Then I would hook red and white wires together.This should
turn your futnace come on and run. If it does then I would just get t-stat exchanged.Hope this works for you. Good luck and thank you.

Jan 24, 2011 | Honeywell Programmable Thermostat Heater

1 Answer

I have a red and a blue wire coming out of the wall. I am not sure what I need to hook them up to in terms of O/B Y R G W. Help!

Hi, if this is just a forced air gas fired heat only heater, put the red wire on the R terminal and if no white wire, use the blue and connect it to w for heat. Normally for heat only, with 2 wires, they will be R for hot and White for heat. First, take the 2 wires and hold them together to see if the heater will start. If it is wired correctly at the unit it will fire up if all is working. Don't be afraid of shock, as this is very low voltage. Hold together and give it a couple of min. to see if it fires. If so connect as I have said. If not, replace the stat with a heat only stat that has only 2 terminals. If its a wall heater, you will need a heat only milivolt stat to replace the 24 volt stat you have. You can use it and it will work, but you may have problems in the future. Please rate me on this, and if you need more help just comment by my user name below. Keep me posted.
A/C, & Heating Contractor

Oct 21, 2010 | Honeywell Programmable Thermostat Heater

2 Answers

Do i need a low voltage transfomer to hook up my

what kind of thermostat to you have, did you purchase the thermostat with the unit are you upgrading to a electronic thermostat, If you are using the mechanical thermostat that comes with the unit you will not need a thermostat. please see the link below and page 11

Jan 17, 2010 | Honeywell Programmable Thermostat Heater

2 Answers

I am trying to install a fahrenheat f2543 heater with a fta2a double pole thermostat. there is a 12/2 wire coming into where the heater is being installed. how do i connect the red and black to the white...

Hi, this is very easy for you to do.The 12/2 Romex wire coming in is the power which you know. What you do need to know, is the voltage coming in? Sometimes they will use 12/2 Romex with ground for 220, 240, operation. You need to know if the T-stat is Line voltage 220, or 240 volt. You have to have the same voltage for both for it to control. Reguardless of the voltage, lets say it is in the 220 and up range. You take one of the 12/2 wires, white or black and hook it to the black or red on the T-stat and the white to the other one, red or black. Thats it, you are done! If the T-stat is 2-pole I am sure it is a high, Line votage T-stat. Best of Luck,

Nov 09, 2009 | Fahrenheat Built-In Baseboard Thermostat...

1 Answer

My problem is....On my new Honeywell RTH230B thermostat the color code is Rh, Rc, W,Y and G. My wire colors are red, orange, blue, white and black. I can obviously match up 4 of them but where the heck...

First you are using abnormal wire colors for a furnace. Second.... if you have an air conditioner hooked up to this furnace, you will need to install a jumper wire between rh & rc. I am assuming this is a natural gas furnace. Usually the red wire to R terminals. Usaully the white wire to the W terminal. Take the door off of the furnace. Find the thermostat wire connection in the furnace. What ever color wire is on the R terminal in the furnace should hook to the R terminal on the t/stat. Whatever color is on the W in the furnace goes on the W on the t/stat. Whatever color is on the G terminal in the furnace goes to G on the t/stat. And the Y in the furnace to the Y on the stat. and the G in the furnace to the G on the stat. Most applications use only the R, W, G, & Y ( always put the jumper wire between Rh & Rc)
Good Luck
Hvac Teacher

Mar 26, 2009 | Honeywell Programmable Thermostat Heater

1 Answer


Well, it's an be only one of three things then (in order) -

1) Bad wiring connection, particularly the middle pair of white and black wires connected to the supply wiring, or
2) One of the breakers or fuses has tripped or blown, or
3) Bad thermostat.

If 1 is OK, check 2 (double check if breakers, sometimes they don't look tripped when they are), and lastly, take the stat back and get another one.

The ground is secondary, and it is assumed your living in a house where 14-2, 12-2, or 10-2 with ground was NOT used. If it was, hook up the ground. If not, it's OK. The grounding requirement was added to the NEC after your house or whatever was built. It is not electrically active or needed for this circuit.

Reply back what your findings are. Will be glad to help!

Feb 01, 2009 | Honeywell Programmable Thermostat Heater

1 Answer

RTH2520B Honeywell Programable Thermostat wires

Hi soozankrayg!
Your problem should be pretty simple. (assuming that it is a typical 24volt system) you should hook up the black wire to the "RH" terminal and the white wire on the "w" terminal. Make sure that you turn off the power to the furnace at the breaker or the furnace itself before attempting this. The reason for this is that you can cause a short and either break the fuse at the furnace or burn up the circuit board. This can happen very quickly and is very common when a thermostat is removed.

Jan 28, 2009 | Honeywell Programmable Thermostat Heater

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