# Dual Fuel Calculator (Trane)

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#### MooseMan

##### New Member
Picking up off a previous thread: System is a Trane: XC95M Furnace, XV20i Heat Pump, and XL1050 Control. I'm trying to understand how heat pump to propane cutover works.

-By default, Compressor Heat Lockout was disabled. At 20 degrees, it sounds like an airplane.
-In activating Compressor lockout I can manually set the cutover or automatically
-When choosing automatically calculated I entered \$.126 (cost / kwh), and \$3.2 / therm (rough conversion from propane to NG)

The "Auto" method spits back a 5 degree cutover, which I don't think it could ever keep up with. So I selected 25 degrees simply because it is quieter. Does this make sense? Any real-world guiding points here?

#### Fitter30

##### Well-Known Member
What sounds like a airplane? There's 3.41 btu's per watt resistance electric is 100% efficient
Electric 3412 btus kw
Lp 91,502 btus per gallon
Ng 100k therm
Have to cost by if there's delivery charge, taxes and efficiency
What manual are u looking at?

#### MooseMan

##### New Member
What sounds like a airplane? There's 3.41 btu's per watt resistance electric is 100% efficient
Electric 3412 btus kw
Lp 91,502 btus per gallon
Ng 100k therm
Have to cost by if there's delivery charge, taxes and efficiency
What manual are u looking at?
The air source heat pump. At lower temps, it spins harder to produce heat. So when dealing with a heat pump the BTU's / kw equation becomes less efficient as it gets colder out. At 22 degrees the heat pump is quite loud trying to move the volume of air needed to extract heat. I ended up saying screw it, and cutting it off at 30 degrees. Below 30, it shifts over to propane. I could push it down to 25, and in the right conditions I believe it would choose to operate at lower temperatures. But it was annoyingly loud.

#### Fitter30

##### Well-Known Member
The spec on sound 54 - 76 DbA unit won't be any quieter in the summer under full load. Supposed to be one of their quite units.