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Hello i just moved into a new home with an old honeywell round…

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Hello i just moved into...
Hello i just moved into a new home with an old honeywell round thermostat with 4 wires, red, black and what looks like 2 copper with no shielding? i purchased a lux tx1500 automatic thermostat. i have both heat and central air, so i need to connect it accordingly, my problem is that the wires were really short, i had to unscrew the wire holding screws before i could remove it from the wall, i dont know which wire R, R(something unreadable) but next to the G, the G wire and the Y wire? Can U assist?
Submitted: 7 years ago.Category: HVAC
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Answered in 18 minutes by:
5/8/2011
HVAC Technician: BillyHvac, Journeyman HVAC Tech replied 7 years ago
BillyHvac
BillyHvac, Journeyman HVAC Tech
Category: HVAC
Satisfied Customers: 23,154
Experience: Endorsed for unlimited heating, cooling, oil burners, boilers, refrigeration, hydronics
Verified

 

Hello,

 

Odds are you had a R and a Rc but they were connected with a short jumper wire.

 

On your new thermostat do you have just an R or an Rc or Rh also?

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Customer reply replied 7 years ago
i have 4 wires and to get it off the wall i had to remove 4 little screws inside the round unit. those had little tiny letters which i couldn't see until it was off and the wires had been removed, thus the problem. it looks to me that the ones on this unit were connected to the R, R with something little, G, and Y, they were connected separately to the 4 screws. the new unit has G, RH, RC, Y, W, O, B, C. The RH and RC on the new unit are jumper-ed together
HVAC Technician: BillyHvac, Journeyman HVAC Tech replied 7 years ago

Thank you,

 

so the issue is we dont know whic wire went where?

 

Hold the red wire in one hand...one at a time touch the other wires to the red.

 

Red is going to go to the rc/rh...but we need to know the others.

Touch the black to the red and tell me what turns on...blower, heat or outdoor unit.

 

 

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Customer reply replied 7 years ago
i have touched and held the red to each of the other 3 wires and nothing happens, the heat and ac both worked with the old round thermostat. now i am really worried that i screwed it up totally!
HVAC Technician: BillyHvac, Journeyman HVAC Tech replied 7 years ago

Is the furnace turned on?

 

 

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Customer reply replied 7 years ago
Yes i had shut off the circuit breaker but turned it on after you last request. the old round one had simply and off, cool or heat setting along with fan on or auto switches thats it.
HVAC Technician: BillyHvac, Journeyman HVAC Tech replied 7 years ago

 

What is make/model of furnace?

 

 

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Customer reply replied 7 years ago
hold on i have to look and it now appears that further inside the wall was a 5th wire which also if i touch the red to nothing happens. Furnace is Power Oil/Power Gas Furnace, Model CMF2
HVAC Technician: BillyHvac, Journeyman HVAC Tech replied 7 years ago

Thank you,

 

Did the old thermostat have a "C" terminal that could have been hooked up?

 

 

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Customer reply replied 7 years ago
No C that i can find. there are two sets of numbers inside the old if that helps. under the upper section under the plastic knob to set the temp, there is a little placard with T87F 2873 3 and below that 0025. on the top of the underside there is Q539A1147 something unreadable tiny, and under that 0018 thats all the writing aside from the letters at the screws
HVAC Technician: BillyHvac, Journeyman HVAC Tech replied 7 years ago

 

 

Ok,...oil or gas version for furnace?

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Customer reply replied 7 years ago
gas
HVAC Technician: BillyHvac, Journeyman HVAC Tech replied 7 years ago

 

 

The only other option is to open the furnace and check thermostat connections there. If nothing at all happens when wires touched together is a sign of a bad transformer.

 

To check would require a meter to see if unit is making 24 volts.

 

I apologize but it is now time for hands on checking with a meter.

 

Billy

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Customer reply replied 7 years ago
the furnace is brand new, and was running fine until i removed the thermostat from the wall. if i knew where the wires where i could just put that one back on the wall
HVAC Technician: BillyHvac, Journeyman HVAC Tech replied 7 years ago

If the wiring were shorted it can burnout the transformer.

 

The method of bypassing the thermostat did not activate any function thus I am concerned about the thermostat power.

 

Something should have happened when we touching wires together...the fact that nothing happened means our control power is missing.

 

I will opt out to let the others have a look for you and see if there are any suggestions.

 

 

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Customer reply replied 7 years ago
It seems i have 5 wires, the colors are very difficult to see, there is one red, the others ? however if i touch the red to one the heater starts, if i touch the two others the ac systems starts, the fifth wire i dont think was hooked up but i am not sure? please advise. i have a new lux tx1500E which wires to use and connect to which connections please advise. i was told by billy from your group that if i touched the red to other wires things would happen that isn't the case, 2 wires start the heat, 2 start the ac system, the 5th? Please advise!
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