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T-Stat Replacement I am trying to replace an old t-stat with a new Ranco ETC-111000-000. The old t-stats have no idea what they are they are old and rust can't read. The old ones are hooked up with only two wires, (where i used to work and bought these from we used 4 wires so im lost) The old one has a red, yellow, and blue dot on them. Yellow is on top, blue middle and red bottom which is common. I have a Blue wire hooked up to common and a orange wire goint to yellow dot(?) on my new t-stat where do i put the orange wire at? I know blue will go to com. Thanks Brenda

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Re: T-Stat Replacement

You will have to trace the wires from the source, unfortunately, the colors may not be accurate. Do you have a 24v heat and cool system? I am going assume the answer of yes, as this is the most common. If you have something different, we will need to go over this again. According to the new thermostat, the red is the power, it will come from the low output side (24volt) of the transformer. Green is blower fan, it will go to a relay that turns the fan on when the thermostat is set from auto to on. The white is heat, this will go to the pilot/ gas valve etc. Last is yellow or blue, either color is for the cool. This goes to the control for the compressor, usually the contactor.

Posted on Jan 07, 2008

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need full model number of w/r thermostat for other wires

Jul 02, 2011 | Air Conditioners

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Hi there We had a powercut overnight and now the ST7100 will not run. I can hit set and set the times etc but when I hit Run the screen goes blank. Any ideas greatly appreciated. thanks

Hi, when you lost power, it may have taken out a fuse to the indoor unit if this is the kind of system you have, I don't know. As far as the stat going blank when you hit run, it may be the 24 volt circuit board fuse, I would need more information on the system you have. See if your stat has batterys also.If nothing is running at all, check all breakers, fuses and so on. If you do have a split system, the indoor unit will have a circuit board where the stat wires are terminated. The fuse looks like a auto fuse, 3 to 5 amp. This may be blown. If so, replace and your back in business. Like I said, if I new what kind of unit you have, it would be very easy to trouble shoot. It may have taken out the transformer also. Just make sure all power is restored, no breakers tripped and fuses blown at the indoor unit. This should be very easy for you to take a good look at this unit. The display on the stat runs off batterys most of the time, but some are powered from the transformer. Try what I have said, as you will need to have 24 volts to the stat to fire up the unit, and if you do and the stat still goes blank, you have a faulty stat board. Keep me posted. Best of luck to you.
A/C, & Heating Contractor

May 12, 2011 | Air Conditioners

1 Answer

I replaced an old mercury T-stat (York with model number 2TH11704024) installed a new T-stat (RTH6350). The wires that I I have are O (orange), G (green), Y (yellow), T (gray but not used in new T-stat),...

Did you shut the power off to the air handler/furnace...... before you installed the new thermostat??? You may have shorted out the transformer or blown the transformer fuse...... If you try to put the Fan switch on the stat to Fan ON does the fan come on ..... if it does the transformer is OK.. On the new thermostat did you program it to tell it that you had a heat pump system ???? Looks like you had it wired right. Here is a pdf manual for a RTH6350

Its on page 13 Advance setup for tell the new stat that you have a heat pump....There is also a Honey well Hot line on page 2 Hope this helps.

May 01, 2011 | Air Conditioners

1 Answer

Can you change out reset buttons on hot water heaters

Yes, by replacing the thermostat.

The reset is a part of the t-stat.

Disconnect power to the heater.
Remove the wires one at a time and place them on the same terminals for the new T-stat.
When all wires are changed to the new t-stat, remove the old one and install the new one. (Usually a clip and one screw)

Dec 23, 2008 | Air Conditioners

1 Answer

Have an old honeywell room stat (type with round temp knob) and have taken off wall to allow for decoration. Now heating does not work. Any ideas on whether it's broken or alternatively can it be bypassed.

jumper red to white and it should bring on a call for heat. if it does then you probably damaged stat on reattachment. do you self a big favor and go to a digital stat. you probably have a red white yellow and green wire. hook them up same way on new stat. if you have an extra wire you can pull a common and power the new stat off the transformer, if not you can get one that uses batteries. robertshaw makes some good ones 9400 9401 etc. you need straight cool with gas furnace. they are great. no need to get to fancy and avoid the ones with programming and all. they are way to complicated unless your into lots of programming and tech details. plus those old honeywells are almost impossible to get perfectly level on the wall and if they are not level they will perform way out of whack

Oct 28, 2008 | Honeywell Air Conditioners

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Carrier heat pump

fuse is usually a small resetable breaker on the side of the transformer, or a traditional screwin fuse with a plastic cap on one end that is a specialty fuse and is available at most motor shops or elec supply houses. or its a auto type plug in fuse on the circuit board usually 5 amps or three amps. first turn the fan switch on the stat from auto to on. does fan run? if it does you have high and low voltage and your wired wrong. if it is in the stat you are usually looking at red connects to red . yellow to yellow, green to green , orange to orange, white usually to white, that leaves a common power wire to operate the stat, usually connected to the common term on the new stat . this can be any color and is necessary for the new stat to think and work, if it has batteries it will have a display but it needs a red and a common to think and work. this wire can be any color and if your old stat had no common which a lot didnt then youll have to add one. carrier also has a emergency heat strip wire sometimes labeled x2 etc. you can usually jump white over to x2 to perform function if needed. good luck.

Oct 22, 2008 | Air Conditioners

1 Answer

I have a coleman evcon t-stat that is using 7 wires. I want to switch to a honeywell th3110d non-programmable t-stat but don't know where the wires should go.

The most common wiring is: This sometimes varies as to installers preferance.
Red wire is your supply power to the T-stat. R terminal
Green wire is the blower fan. G terminal
Yellow wire is compressor contactor Y terminal
older units used a blue wire to Y
White wire is heat auxilary or black wire W terminal
Orange wire is reversing valve O terminal
Blue wire is the common C terminal
Black wire can be emergency heat E terminal
Best thing to do is replace wire for wire from t-stat to t-stat
or write down the colors to which terminal on the old t-stat and match to the new. make sure you SECURE POWER to the Air Handler, furnace and condenser before replacing any t-stat.
It is very easy to short the wires out if the power is left on and take out your A/H low voltage fuse or transformer.

May 18, 2008 | Air Conditioners

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