Is a heat pump with defrost function worth it?

[gsf4726]

I've been looking into switching to a heat pump from propane to heat my in-ground pool and spa. My main motivations for switching are the high cost of propane (delivered, $3+ per gallon) and the generally terrible customer service from propane suppliers in the area.

I've read that having a heat pump with a defrost function (either as an added feature to a heat-only pump or inherent to a heat-cold pump) allows the heater to function in colder temperatures below 50 degrees. What I'm not real sure about is, how *well* a heat pump would actually work in such a case. I can't imagine ever wanting to heat my pool in weather that cold, but we might want to use the spa. Would it actually work heat up my spa to 100 degrees if it's 40 degrees out?

I should also point out that I'm in central FL, and we're below 50 degrees only a few days a year, if that.

At this point, I'm thinking in my case that a defrost function isn't worth the extra expense. I also have no use for a cooling function as my pool is in a screen cage which prevents it from ever getting too hot.

Would love some feedback from the more experienced to confirm that suspicion or point out something I'm missing. Thanks!

 

[revitup]

Heat pump will not function below 50 degrees ambient by design (or actually 53 degrees in the case of our Hayward HP). If you want to heat in those cold temps you'll have to stick with the gas heater.

 

[swamprat69]

Heat Pump BTU output is rated at 80 degrees outdoor air temperature. As the outdoor air temperature drops the heat pump BTU output also drops. As to the defrost function, frost on the outdoor coil acts as an insulator to heat transfer of the coil. This would less important in a single digit low humidity enviroment like Las Vegas but more important in a higher humidity enviroment. Running time for the heat pump would also be a factor in coil frost buildup.

 

[Bama Rambler]

For a residence the defrost function is definitely worth the cost, however in a pool installation when it gets cold enough for the defrost to function you're not going to be heating the pool even if you're running the HP. So, I wouldn't pay any extra for that function.

 

[scottts]

You're in a much more humid area than I am, so your low-temperature performance will be better as you will have more energy in your air at any given temperature (enthalpy). In AZ when the temp is below about 56 degrees in the winter the heat pump I have will freeze up very fast as it drops the air temp a lot because there is no humidity.

 

[gsf4726]

Thanks all, really appreciate the info.

It seems like a defrost function on a pool heat pump really doesn't have much practical value then, which probably explains why there are not very many options with it explicitly.