Heat pump vs Propane Heater

[RochesterMark]

What about BTU output? We are putting a new inground pool in September and the pool store said we should us a 300,000 btu gas heater. I would like to go with a heat pump but the largest I have seen is around 150,000 btu. I hope that it is ok to jump in on this thread like this. I'm new to the pool forum.

Thanks

Mark

[Poolsean]

Mark,

Welcome and yes, it's fine to jump in....the water feels great!

First, it's important to know that most gas heaters are approximately 80% efficient, so the 300,000 BTU gas heater is only putting out 240,000 BTUs, with the other 60,000 BTUs wasted out the top vent.
Heat Pumps are highly efficient and can do the job of maintaining the heat in the pool. Not sure about the 150,000 BTU rating on a heat pump though. They really don't put out that much. However, that's not what's important. It's a matter of maintaining heat, rather than introducing heat to the pool whenever you're looking to use it.
This is best done by using a solar cover and allowing the pump to operate long enough to keep the pool maintained. In the longrun, it will still be much less than running a gas heater.

How large is your pool going to be? Indoor or outdoor? Will you be using a dome in the winter or winterizing?

[RochesterMark]

We are putting in a 24' by 40' vinyl "free form" pool in the Rochester New York area. It 's a outdoor pool that we will winterize. Do you know the average time it takes to recover the extra cost of the heat pump? From what I have seen most heat pumps are about 2X the price of a gas heater.

Thanks

[Poolsean]

It really depends on how you're going to be using your pool. On average, although the initial cost of the heat pump is about 2x, the cost savings is about 50 - 70% less than running gas. Which means you're actually able to afford to heat your pool and spa.
The cost difference may take a few seasons, but after that, it's all savings. The other considerations are warranty, and typical replacement parts that typically take place with gas heaters (with Cupric-Nickle heat exchanger failures), whereas most heat pumps will offer a titanium heat exchanger (virtually impervious to chemical attack and most manufacturers offer lifetime warrantees on the titanium).

[Poconos]

With all due respect Sean, you're in Florida and this guy is in Northern NY. Big climate difference. 'Average' costs can be misleading in my opinion. One big factor in how long it takes to recover cost is the electric rates which vary widely around the country. Another factor is the air temperature (heat sink) when the thing is running which affects efficiency of a heat pump. I agree with you on the heat exchanger statement, but you have to also consider the other components which are about the same as a central air conditioner. I admit I don't know the answer to this one but 'efficiency' to me would mean overall cost efficiency which includes non-recurring and recurring costs figured over a multi-year time frame. I used to use propane until the price went through the roof and now I use solar. Just my nickels worth.
Al

[Poolsean]

Al, oddly enough, the Northeastern US happens to be our second largest area of Heat Pump penetration! We realize that homeowners are not looking to keep their pools opened all year around. Rather, they are simply looking to extend the swim season, and to be able to be the FIRST to open their pools, and the LAST to winterize it. This comes out to about March/April through Sept/October.
All heaters loose efficiency when the temps are cooler. Most standard heat pumps will shut down when the air temps fall into the low 60's because of ice build up on the evaporator coil. Hot Gas Defrost options will melt the ice and allow the heat pump to continue working down into the 20's and 30's...albeit, at a lower efficiency. I would admit though, not too many people will be using their pools or spas when it's that cold. AND if you do want your pool/spa heated at those temps, I will cede that chore to a gas heater!

When you maintain your water temperature, the amount of heat lost overnight mostly to evaporation will depend on if you use a solar cover (20% heat loss), liquid blanket (30 - 35% heat loss), or no cover (50% heat loss).
Basically, a heat pump that is allowed to maintain a temperature (as opposed to heating on demand) has less work to do. Although the same heat loss and recovery statement is true with a gas heater, it is just so much more expensive to maintain heat, therefore the task of the gas heater is not commonly left on to maintain heat.
So, it is asked to increase the temps from a lower water temperature, in a quicker time frame. This is the environment for a gas heater (IMO). Perfect for spas and a pool that is not used frequently when it starts to cool off.
The Heat Pump, again, allows you to maintain the heat, efficiently, so that the pool is always ready to use. No more waiting for it to heat up and watching that gas meter just spinning away!
(sorry for the sales pitch).

[CarlD]

If you have the space, do solar AND a heat pump/gas heater. With the solar heat, and a solar blanket, you should be able to go all summer and a little beyond--in both spring and fall, with zero operating costs. Solar DOES work, but only when the sun shines. The blanket (I prefer clear thicker ones) acts like a greenhouse.

Personally, if you have access to natural gas, rather than propane, that's a far cheaper choice. If you are talking a grill, the cost of plumbing NG doesn't pay in savings over propane. But in a 400K BTU heater, the cost savings are substantial.

Yet, despite that, if you are talking temp maintenance, you are best to go with a heat pump--it will still be cheaper than the NG, much less the propane. Combine it with solar and a blanket and you'll have a nice, extended season.

I just have a personal bias against gas heating--it seems there are SO many ways to recover heat cheaper and more environmentally friendly. I live in N-Central NJ and I have NO trouble keeping my pool between 85 and 95 solely with solar and a solar blanket.