Need help with thermostat replacement wiring


  #41  
Old 09-21-14, 01:26 AM
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normally you will have electric heat strips installed in the air handle
Would it have an extra wire going to thermostat?

than come on when the heat pump goes into defrost mode in the winter and also serve as emergency heat if the heat pump breaks down
Is it possible that I don't have it? We don't usually get get temperatures below 50 in the winter.


It appears that the heat and A/C is working properly now. I will test some more.
 
  #42  
Old 09-21-14, 01:29 AM
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That is what the white wire on W is for; auxiliary heating, usually electric heat strips. Glad to hear it appears to be working properly now.
 
  #43  
Old 09-21-14, 01:30 AM
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I think it's working now. Man, I owe you a beer keg!
 
  #44  
Old 09-21-14, 01:36 AM
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That is what the white wire on W is for; auxiliary heating, usually electric heat strips. Glad to hear it appears to be working properly now
That's where I get the heat from, the W wire. It' not a auxiliary heating, its the main and only source for heat in the house, but I could be wrong. Bottom line the only wiring in the air handler, is the actual fan and low voltage wiring and as far as I know, any kind of heating would require a nice thick wires.

Thanks again.
 

Last edited by igorek24; 09-21-14 at 02:03 AM.
  #45  
Old 09-21-14, 07:59 AM
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Actually the W wire is for auxiliary heating. On the majority of heat pumps the reversing valve for the heat pump is activated in cool. So when the thermostat is set to heat the O wire sends a signal to the heat-cool relay inside the condenser to move the reversing valve. At that point the outside unit becomes the evaporator coil and the inside coil becomes the condenser. When the outside temperature drops to a certain point the defrost cycle begins and the fan is shut off outside while the unit defrosts. That is when auxiliary heat strips come on to temper the air inside the house as the blower is actually blowing cold air from the vents. The heat strips are also utilized for emergency heat in the event the heat pump breaks down. At that point you can use the heat strips as the heat source until you can get the heat pump operational again. You can usually tell if you have heat strips by additional breakers inside the air handler or a larger than normal breaker for the air handler.

Your wiring is pretty much back to standard color code. The only one off is the other white wire on the O terminal and and the green wire outside going to the orange wire at the condenser.

I suggest you take several digital photos of the wiring at the thermostat and at the outside unit for future needs. Also, it would be a good idea to save a copy of the service manual I linked in this thread.
 
  #46  
Old 09-22-14, 12:50 PM
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Thanks firedawgsatx,
I have taken some pictures of the thermostat wiring as well as put flags that came with the thermostat on the wires. I think I'm going to replace the whole system. I just got a quot from Home Depot for $6100 and if I want to move the air handler to the attic (which I do), it would be $6900. It looks like its 20 years old and I think that the new one would be more efficient (13 SEER). I would probably have them replace the low power wiring too. So, my next question, right now i have a 3 ton system for 1300sqf. The HD guy said that I don't need that much and suggested a smaller one for my squire footage, should I stick to 3 ton or do you think it would be to much?

Thanks
 
 

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