Lennox 13HPX - Heat pump reversing valve stuck on heat, ~3 years old.

Now if you are allowing or forcing the backup (Emergency) heat to kick in yeah that will blow your electric bill to the moon, even dipping down in the teens here in Atlanta I don't ever recall seeing my Nest calling for the backup heat strips to kick on. IDK your system though so just passing on what I know - your climate is prime for a heat pump though.

Some of the slack-jawed yokels that pass as HVAC technicians in some places think that the heat pump should be locked out below 40F and only backup emergency strip heat used below that temperature.

And I think some of them actually go as far as to add an outdoor thermostat to make sure only strip heat is used below 40F.
 
And I think some of them actually go as far as to add an outdoor thermostat to make sure only strip heat is used below 40F.
That is just wrong, as even at extreme cold, heat pump COP stays above 1.0. That means that running the compressor will still deliver more heat to the inside than the same amount of electricity used for resistance heat. The problem is that it won't be enough BTU to keep the house warm, so the resistance heat is also needed.

When the backup heat is a system other than electricity then the relative costs of the two fuels need to be considered.
 
That is just wrong, as even at extreme cold, heat pump COP stays above 1.0. That means that running the compressor will still deliver more heat to the inside than the same amount of electricity used for resistance heat. The problem is that it won't be enough BTU to keep the house warm, so the resistance heat is also needed.

That is true. At my house, because the thermostats (it's a zoned system) I have seem to be way too quick to turn on aux heat, I have it wired through a switch. One winter it got down to about 5F outside (rarely happens). Even with aux heat disabled it was still able to keep the house at 60F (my house is very "tight"). I was OK with that. Still didn't turn on the switch to enable aux heat.
 
Back
Top