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We are trying to install a new thermostat for our heating and ac. and the wiring colors are different.

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Heath Moyer

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Hello my name is Heath it will be my pleasure to assist you. Red wire to R terminal on the urnace and the thermostat. White furnace and the wire to W or w1 on the thermostat nd the furnace, Use the brown wire on the W2 terminal of the furnace and the thermostat., Yellow wire to the y or y1 terminal on the furnace and the thermostat, Green wire to the G terminal on the furnace and the thermostat, Use the black wire to common on the furnace and the C terminal of the thermostat, Use the blue wire on the Y2 terminal of the furnace and the thermostat if you have a two stage air conditioner.

Posted on Sep 11, 2011

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Wires don't match the new thermostat posts. The wires from the furnace are Red,Blue black and white The posts in new thermostat are B O G Y not used R and Rc Can't figure which to put


The wire colors are for the following functions ......red - 24 volts white - heat yellow - AC green/blue - blower (fan) red is connected to the R with a jumper between R and Rc What type of furnace/heat do you have ???? Electric. oil, gas .Forced hot air, baseboard, steam, heat pump, or ?????? Different systems use different connections and need a specific thermostat for that application !!!

Dec 13, 2014 | Heating & Cooling

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How to change a thermostat yourself


Choosing your new thermostat:
Firstly you have to ask yourself why you are changing your thermostat. Is your old thermostat simply broken? Are you wanting a simple upgrade from analog to digital? Are you looking to save on energy costs using a programmable? Are you attempting to integrate your central system into a smart home network? Whatever the reason your choice of thermostat should not be simply the cheapest on the shelf. Different system types may require different thermostat types.
Before purchasing your new thermostat you need to figure out what kind of system you have. The general idea is *H/*C, denoting the number of heating/cooling stages and options, and fuel type (heat pump, gas furnace, electric furnace, etc.). An example would be a typical heat pump- it has a single cooling stage and a dual heating stage (heat strips, compressor) making it a 2H/1C heat pump thermostat. I usually install the Honeywell FocusPro 5000/6000 series for non-programmable/programmable applications for it's ease of use and general reliability.

Before beginning the swap always make sure power is off to both the indoor and outdoor sections!

Determining which wires go where:
First off, you may not ever rely on wire colors to guide you to the proper terminal. We have standard practices for wire color to function, but this varies from region to region and sometimes if a wire shorts out a substitute in the bundle may be used. When removing the old thermostat physically writing down or labeling the wires is not an exercise in tedium- it is almost necessary and something which I do every single time. You will usually have these terminals on the new device:
Rc- Cooling Power (usually jumpered to R/Rh)
R/Rh- Heating Power (usually jumpered to Rc)
Y- Primary Compressor
C- Common
O/B- Reversing valve (activated in cooling/heating)(Heat pump)
W- Primary heat (Furnace or Electric heat)
G- Indoor Blower
E/Aux/W2/X2- Emergency/Secondary heat stage
Y2- Secondary Compressor (2 stage cooling)
L- Communicator for E-Heat (Heat pump)
If you do not have all of the terminals on the old as you have on the new it may not be the end of the world. Required terminals are an R, a Y (if AC is present), a W/W2/E/Aux/X2 (if heat is present), an O/B (if heat pump), and usually a G. Common is optional most of the time as it is used to power the thermostat only and batteries may be substituted. L is not commonly used. If you have any doubts as to which wires go where, stop now. Miswiring can destroy a system's low-voltage and potentially start a fire.

Replacement:
After labeling the old wires and removing the old thermostat, you must attach the new baseplate. Leveling the baseplate is not as important as it was with older mercury thermostats, but still applicable at least within +-5 degrees of rotation. If you are attaching the baseplate to drywall with no backing wood installing wall anchors (usually supplied) is key. Make sure you have a proper length of bare wire (not too long, not too short) before attaching to the terminals. Do not overtorque the screw lugs. Pull back on the wires after attaching them to ensure the connection is proper. It is a good idea to plug the hole through which the wires come with something (I use plumbers putty) to keep a draft from effecting the thermostats temperature. Many thermostats will require some pre-programming before hooking up (refer to installers guide)- I find this much easier to do via batteries before attaching the face to the baseplate. Once the face is on and the power returned to equipment, test the system. Keep in mind modern thermostats include a 3-5 minute delay for compressors as a protective layer.

Common Pitfalls:
Zone system wiring can be confusing and is not as standardized as it should be. If you have a zone system and plan to purchase new thermostats it is highly recommended to call in an experienced service technician.
High SEER and IQ drive systems use very different types of thermostats than conventional systems. For now the newer technology has yet to be perfected in the public market and these changeouts are best left to an experienced professional.
Some older thermostats use B as common (Trane Weathertron for example) This is not to be confused with B as a heating changeover valve and if it is can blow out a fuse,transformer, and/or your brand new thermostat upon startup.
Most face to baseplate interfaces are pin based- if one is not quite careful bending one of these pins during attachment can be irreparable.
Common is the least standard color across installers. Most use either brown or blue, but I've seen some use green and black, usually used for blower and secondary heat respectively. Never assume wire color as a standard.
Most of the service calls regarding thermostats I receive come from homeowners who have purchased and self installed incompatible thermostats. This is something I do everyday for a living, not so for the average homeowner. Take your time and do your research.
Save your manuals- all of them. Many cheap offbrands can be next to impossible to find manuals for online.
When in doubt, call in a pro. Most of us charge around $70-100 to install a thermostat (plus cost). This is almost always much cheaper than a service call to diagnose and repair a low voltage problem.

on Sep 25, 2011 | Heating & Cooling

1 Answer

Which thermostat to use 4-wire Goodman gas furnace


blue is common. never let that wire touch any other color or you will short the transformer. Use a thermostat for single stage gas heat. R=Red W=White Y=Yellow which should go to the outdoor ac contactor and C=Blue which should also go to the outdoor ac contactor. If in doubt call a qualified Heating contractor to help you install. It can get quite expensive letting the smoke out of your parts.

Aug 21, 2014 | Heating & Cooling

1 Answer

I installed a new thermostat on my hvac system and the heat is not working anymore.


On that thermostat there is an R and an RC wire connection, the R is the power wire for heat and RC is the power wire for cooling. If you connected the power wire (normally red in color) to the RC only the fan control and AC control will work, there has to be a jumper wire between the R and RC terminals (assuming there is only one control transformer) for both the heat and cool functions to work.

Jan 21, 2014 | Honeywell Programmable Thermostat Heater

1 Answer

Hooking up a new thermostat honeywell rth7600 from a honeywell t8411r. we hooked up the wires as shown in the installation manual- we have fan but no cold air blowing out or it feels like the heat is...


apparently who ever did the wiring installation did not use the Proper color coding when they did the install. Now you must trace the wiring to the appliance and wire accordingly.

Oct 10, 2013 | Honeywell Programmable Thermostat Heater

1 Answer

Havc thermostats


I will assume you did not write down what color wire you took of each letter on old thermostat? Sometimes color of wire doesn't matter as some installers will use whatever color. If you noted where each wire was on old thermostat, just put same color wire to same letter on new one. Under normal situation. y is for compressor (cool) G, is for fan (on AC) , RC is 24 volts from transformer for AC side, RH is 24 volt transformer from heat/furnace, and W is for other wire from furnace, is furnace is only 2 wire system. Was there any wire connected to A on old thermostat?

Apr 11, 2012 | Heating & Cooling

1 Answer

Three wires not marked for new Thermostat!


You will need to go to the heating system and see what color wires are hooked to that. Typically the black and white wires will be used unless they used another color due to a bad wire. Hook the colored wires to the R or RH terminal on the thermostat and the other wire to the W terminal. You can also try taking the wires you have and one by one twisting them together and have a second person inform you when the heating system turns on. Take those two wires and hook them to the terminals I mentioned above.

Jan 14, 2010 | Honeywell Programmable Thermostat Heater

2 Answers

Honeywell RTH230B works on AC not on Heat


check wiring to furnace check wire hook ups on board match letters and colors sometimes installer use what ever wiring they chose on letters

Oct 16, 2009 | Honeywell Electronic Programmable...

1 Answer

Newly installed Goodman GPG13 gas/electric package unit installed. Cannot get AC to cycle on. Unit produces heat at all thermostst settings.


new unit and old thermostat/wire? thermostat could be bad or bad thermostat wires. try putting in new of anything old. do this wiring practice with the terminals being the letters.

r- red (24 volts)
w- white ( heat)
y- yellow (cooling)
g- green (fan)

Sep 21, 2008 | Goodman Heating & Cooling

1 Answer

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Don't assume the wires at the thermistate are correct.

I had similar and had to go all the way back to the heat/AC controller board. I found the colors weren't attached per spec so was fighting the origional installation at the new thermistat.

Also some digital won't control mutizones proerly

Dec 15, 2007 | Honeywell Programmable Thermostat Heater

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