Trying to decide heat pump vs gas heater.

[Green Goblin]

Planning out my build.

I will be covering the pool with a cover star autocover, and am willing to get an ameri-dome too. I'm in the Nashville, TN area and wondering if anyone has experience with a heat pump in this type of climate.

I'd like to keep the pool over 80deg for about 10 months of the year.

Any thoughts?

 

[PoolGate]

Gas is instant heat. Heat pump is gradual heat. Degrees per hour vs degrees per day. Heat pumps get exponentially less efficient as the temps drop as well. What are the temps in the coldest months you want the pool opened? If 60s or below, the heat pump is going to barely produce. Heat pumps also cost initially twice what gas costs. Covers make a big difference but won't make the heat pump more efficient.

What is your criteria for choosing one over the other? Money? Time? You mention an auto-cover and Ameridome. Both of those will cost way, way more in the long run than the extra money you will pay in gas for a gas heater. My take is if you want heat, get heat. Nothing heats like gas.

 

[Green Goblin]

What is your criteria for choosing one over the other?

I am trying to figure that out! Money in the long term, ability to run at lower temps, long term reliability, ability to be reasonably serviced by local folks... Time isn't as much of an issue for me. No spa, so it doesn't have to be fast heat.

The autocover is happening anyway, regardless of heater, and yes it is ludicrously expensive. The cost for a heat pump installed by my pool builder is $1k more than a gas heater, so it's not twice as much in this instance, and probably I'd make up that $1k in lower operating costs, partly because I wouldn't be able to heat the pool for a period of time too.

You are right about the dome. I really hadn't thought that out as well as I thought I had. I can buy an awful lot of gas for the $5k cost of the dome.

I think some of this thinking has been more emotional than logical. Maybe I do better with something with higher installation costs and lower operational costs. What I don't want to do is get to the point where I don't want to run my heater due to operational costs.

Thanks for your help.

 

[CJadamec]

Its not an exponential loss of efficiency with heat pumps it more of a linear loss corresponding with outdoor air temp and humidity. If you have moist or humid air even at lower temperatures you will still get a good amount of heat out of a heat pump. Moisture in the air contains a lot of energy.

Heat pumps are more expensive up front for the unit. The other cost to consider is how much it's going to cost to run the gas line to the pool pad and if you need an upgraded gas meter to handle the additional flow. If it's a brand new pool install the extra cost to upgrade the wire size to handle a heat pump is far less than running a new gas line.

In the long run it is far less expensive to keep a pool at temperature with a heat pump than it is with a gas heater. If you plan on leaving the pool at the same temp all the time I would vote heat pump and definitely keep the pool covered when you aren't using it.

 

[BMK]

As stated above, if you want a "set it and forget it" type of solution, where the pool temp is pretty much constant no matter when you want to use it, a heat pump is your better bet. If you know when you're going to use the pool, or your usage is relatively routine, a gas heater may be your better bet. You can just ramp up your temp in advance to heat for that specific period.

I can tell you from experience that with an auto cover / heat pump combo, our pool was 88 degrees any time of day or night. Remember, once it gets up to temperature, it only ever has to adjust the water temp a degree or two, and with the auto cover, it will easily stay ahead of the outside temps...at least that has been my experience. In the fall, I would open the cover for my morning laps and the water would 'steam' against the chillier ambient air.

 

[Yev]

Look at historical temperatures for Nashville. I think that a heat pump can only raise 30 degrees above ambient. Lets assume you want to run March to December. I would look at typical Hi and Low temps for Mar and Dec, and then make a more informed decision.

 

[spatel95]

I just had a 140000 btu Hayward heat pump installed two weeks ago for a 20K gallon pool. I live in north Georgia. The temperatures are warm right now so I ran it for five-six hours the first day and after that, I only have to run it for an hour or two. I have a solar cover but I am not using it right now since the temp. is not dropping at night by much. Since you don't have a spa and Gas is expansive in your area like me, then you should probably go with a heat pump.

 

[d103]

In the Atlanta Metro, have an Aquacal Heatwave Heat Pump, since the pool was built in 2009, heats up the spa in about 15 mins to 90-105, have not used when temps have been below 70 for the pool and normally just set it for about 86 and forget about it, and have only used it in the months of Feb (temps permitting) to early June and than late Sept to beg of Nov. In July and August have used it in reverse to cool the water many times. Only repair that I had to make was put in a new display board about a year ago.

 

[Green Goblin]

Thanks for all the input gang.

@BMK-- that's great info. Being in Pittsburgh, you must close the pool for some period of the year though, right? How long of a season could you get up there with an autocover and a heat pump?

@Yev, thanks for the input, I have looked at some historical temps. Hard to know what to make of all of it. Since heat pump performance changes with temperature and humidity, and since my pool isn't built yet and I don't really know how quickly it loses heat typically, it's a bit hard to predict the swim season.

@spatel95. Congrats on the heat pump. I didn't know gas in our areas was considered relatively expensive, interesting. Thanks for your thoughts.

 

[BMK]

Thanks for all the input gang.

@BMK-- that's great info. Being in Pittsburgh, you must close the pool for some period of the year though, right? How long of a season could you get up there with an autocover and a heat pump?.

I generally closed late October and opened late April. I probably could have squeezed a few more weeks in the fall as water temps were not the issue. Ambient temps, yes, but though the HP had to work a little harder, the water temp still held fine. But, by early to mid October, the kids are up to their eyeballs in school activities, sports, etc. The pool gets abandoned, falling leaves get to be a pain, it's time to put it to bed for the winter and look forward to some cold snowy evenings in the hot tub.

Because of it's size and shape, our new build will not have an autocover. We'll see how that goes, but since I've already had one, I'll know what I'll be missing.