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Trane Heat Pump Temperature Set

Posted by fairoaks8 (My Page) on
Sat, Dec 15, 07 at 12:16

I have a new Trane XL14i electric heat pump for my 1 1/2 story house. I live in northern California, so the winters are not that fierce.

When at home we set the thermostat to 68 degrees. When gone during the day or when we go to bed, we set it at 65.
Would it be more energy efficient just to leave it at 68 all the time? I wonder if the electricity would kick on less than going from 65 to 68?


Follow-Up Postings:

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RE: Trane Heat Pump Temperature Set

great question. I also had the same system installed recently. just wondering did you just have one unit installed?


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RE: Trane Heat Pump Temperature Set

If you have electric auxiliary heat strips that come on then that will add to the heating cost significantly. I'd just set it and forget it; that's what I do. I used to do setbacks but the electric auxiliary heat strips would run to assist the heat pump for some time.


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RE: Trane Heat Pump Temperature Set

There are setback thermostats specifically designed for heat pumps that raise the temp slowly during the recovery period to avoid running the auxiliary strips. Or you can do that yourself manually by raising it slowly, no more than 2F at a time, and allowing it to cycle off before raising again.


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RE: Trane Heat Pump Temperature Set

My heat strips don't come on....just trying to save energy costs.


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RE: Trane Heat Pump Temperature Set

A setback temp can indeed be used smartly with a heat pump and save operating $$. It takes a little experimenting to figure what works best for your home. Setbacks in frigid temps, however, are not recommended for a heat pump.

The recovery time of a heat pump is based on outside temps, heat pump btu output at the outside temp, home construction, insulation, ductwork, etc.

A fairly-well insulated home with a good heat pump should have a balance point of 32F. This means that the heat pump should be able to recover from a setback temp without bringing on the aux heat. The recovery time may be several hours based on setback and outside temps.

If its 15F out, the heat pump will be runing aux heat just to keep up, so a setback at this temp is useless.

I have a Honeywell 7500 programmable stat w/smart recovery.

My winter setpoints are currently:

Wake: 68
Leave: 64
Return: 69
Sleep: 66

Best to you.


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RE: Trane Heat Pump Temperature Set

i have the 14i with the Trane 602 tstat. i set mine as follows:

Wake 70
leave 63
return 68
sleep 65

i have yet to have the aux heat kick on. the adaptive recovery does start the HP up around 4-4:30 to be at temp by 5:15 set time. as long as your Tstat has adaptive recovery, you will save money by using setback. if your tstat does not have AR, it will likely turn on the aux heat and not save any money with a setback adn so should be set and forgot or changed out.


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RE: Trane Heat Pump Temperature Set

If the thermostat is set at 63, the air feels like 63. If the thermostat is set at 72, the air from the vents feels much warmer. Is this my imagination?


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RE: Trane Heat Pump Temperature Set

Setpoint doesn't directly affect supply air temperature. But think about it: warmer air (72* air) going across the coil will be warmer than 63* air going over the coil.


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RE: Trane Heat Pump Temperature Set

A follow-up question if you don't mind: Can I presume that it will be more costly to keep the house at a steady 68 than 63 at night and 70 during the day (I'm retired and staying in the house during the day)?


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RE: Trane Heat Pump Temperature Set

fairoaks

assuming your HP is sized correctly and that the idea of setback is operating savings, then it's my opinion that a setback of more than 3 degrees may be defeating the purpose. Obviously, you want your heat strips(or backup furnace) locked out at a certain temperature. My lockout is at 32 degrees. At or below that point, my backup nat gas furnace will come on.What would you say is an average time in your "winter" climate for a five degree setback to recover and satisfy your thermostat setting?

Of course, what is good for one home can be entirely different for another. I just don't like to see a HP runnning constantly for any extraordinary length of time.

IMO


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RE: Trane Heat Pump Temperature Set

Supermann,

Generally with heat pumps, I'd try to keep the setbacks to a minimum. You may consider just a 2 to 3 degree setback at the most, because heat pumps are not meant to recover large temperature setbacks, and when they can't keep up, they bring on the auxiliary heat strips if you have any. I have a heat pump myself, so that's my opinion on heat pumps. They're great for economical heating and cooling, but they're better at maintaining temperature than recovering temperature (air isn't as warm as nat. gas, oil, or propane furnaces).


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RE: Trane Heat Pump Temperature Set

if you really wish to use the setback method I would get a thermostat that allows an outdoor temp sensor to be wired to the t-stat so the stat can use the outdoor temp to help figure the time needed to be at the target temp close to the target time. If you want it 70 degrees at 5pm and it is 30 degrees out it will use the outside temp information to start bringing up the temp much earlier than if it is say 60 out. Same goes for the cooling season. One other additional bonus is you then get low temp cut-out settings that will automatically shut the HP off at temps anywhere below 15F to 35F depending on your preference and go to emergency. Also there is a heat strip cut-out that will not allow the strips to come on at any temp above 40F that can be activated.


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