Heat Pumps-Need some splaining

[scrinch]

I should also acknowledge that at least one member who switched from gas furnace to heat pump was unpleasantly surprised at how much electricity that the system used. I have to say that part of the reason why I'm interested in a dual fuel system is as a hedge in case the heat pump uses far more electricity than expected. A second reason is in the case of power failure the gas furnace and blower can be run off of backup power, while the heat pump likely draws too much current for that. And of course heating while outside temperatures are below freezing is a third reason (unless I decide to spring for one of the new cold climate units).

 

[Music Lover]

We’ve had heat pumps in Texas border, 2 places in Tennessee, 2 places in NC and 2 places in Illinois.

If outside air is much below 20, they don’t work well. Below 32 - maybe.

As others have said, the newer units are different. I bought a Senville mini-split for our cabin (Canadian prairies). It's rated to -30C (-22F). US link:

https://senville.com/mini-split-ac/energy-star/

 

[Gearhead Jim]

We built our house NW of Chicago 42 years ago, all electric because ComEd gave a good rate for an all electric house. After about 10 years, they dropped the all-electric special rate; too bad so sad.

We use a simple air source heat pump for cooling in summer, and heating in winter (with resistance heat strips for when the HP can't keep us warm.)

Our first heat pump lasted 25 years, second one lasted 12 years, third one still ok at 5 years. Kinda like our first electric water heater lasted 30 years, second one now being replaced at 12 years.

Running on just the heap pump with no resistance heat, the HP can keep us comfortable down to about 10'F. Even at that temp, the HP is still more efficient than resistance heating. When temps below 10'F, the heat pump will run full time and resistance kicks in when needed. The HP is set to quit working at 5'F, it's still making heat but not much more efficient than resistance heating and it's putting a lot of hours on the HP. We can be comfortable at -30'F but that produces a big electric bill.

An oversize HP will help only a little with heating in winter, but oversize for summer cooling is nice to have. If you get one too small, not much you can do to improve it without spending big bucks.

Some friends have used groundwater source heat pumps, more complicated and expensive to install but seem to work pretty well.

 

[scrinch]

A year later... OP here. We've decided to go with a dual fuel (or as one company who gave us a quote put it, duel fuel) system. It is going to be installed next week. We ended up going with a medium efficiency variable speed unit from Lennox. The contractor that we're using is the local HVAC dealer connected to Costco, and we're getting a 15% discount through Costco, plus 2% back using the Costco Executive Visa card. The cost of this unit after discounts was about the same as two-stage units from other contractors that had no discount.

The contractor found a couple of ducting issues (undersized return in the attic and crimped duct beneath the house) so correcting those will be part of the job.