100k btu heater worth it in cooler area?

beartoothweb

Well-known member
Aug 28, 2009
188
I found a nice 100k btu heater DSI for $200. My pool is 15x30 with a deap end, so I think I figured 13000gallons or so.

My primary heating method is solar, I have 7 panels active right now, and it's doing a great job on warm days with sunshine. It's starting to turn colder at night, sometimes in the 40's, so it's got me thinking about this part of the season.

I realize that a 400k btu would be better, and I believe the btu to cost relationship isn't totally linear (ie: 400 will not necessarily use more propane than a 100 for the same rise in temp.)

Ultimately, I'm trying to decide of adding a heat pump instead would be worth it, or to just use the propane heater as a quick way for the weekend or whatever. At $2.25+ gallon (ie: per hour), it's expensive, and electricity is cheap. We actually run a hybrid system for our furnace that runs heat pump down to 25 degrees, then switches to propane.

With the solar, we may only use the heat pump for the early 3-4 weeks and the late 3-4 weeks.

Anyway, can someone throw some advice to me?
 

Pool Clown

In The Industry
Sep 5, 2008
1,882
Silicon Valley, CA
I don't think you will be happy with the performance of the 100. You are right about the btu cost relationship, but what you may not realize, is that the 400 will also heat it faster.

Don't know about the heat pumps, other that they are more popular in the cooler climates. Someone should be around soon enough to comment on them for you.
 

bk406

Well-known member
Dec 3, 2009
2,690
Central Massachusetts
A pool heat pump wont really work that well once the air temp gets down to 52 degrees, give or take. They just wont generate that many BTU's to heat a body of water with any efficiency. I have a HP and use it in May, part of June, and September. Once the night time temp gets down to 50 degrees, i dont even bother to turn it on until the sun comes around the house and the air wrms into the high 50's. If your looking to heat the pool when the nights drop into the 40's, then gas would be the best bet, although it will be pricey. It really depends on the day time temps too. Where do you live?
 

beartoothweb

Well-known member
Aug 28, 2009
188
bk406 said:
A pool heat pump wont really work that well once the air temp gets down to 52 degrees, give or take. They just wont generate that many BTU's to heat a body of water with any efficiency. I have a HP and use it in May, part of June, and September. Once the night time temp gets down to 50 degrees, i dont even bother to turn it on until the sun comes around the house and the air wrms into the high 50's. If your looking to heat the pool when the nights drop into the 40's, then gas would be the best bet, although it will be pricey. It really depends on the day time temps too. Where do you live?
I live in Montana. We've had a pretty warm summer, but rainy, and the last week it's gotten pretty cool at night, 45ish. Soon enough, under 52 will definitely be the norm.

My main objective would be to extend the season a bit as needed. My daughter wants to have a pool party in September (labor day), which you never know, could be great, could be cold the week before, so it would be great to be able to heat it for stuff like that, even if it cost me $50 in propane. When it's 42 below in the winter for a couple of weeks, I don't think about the heating cost, it's just one of t hose things.

The advantage of living here though is due to our altitude (4500'), the sun intensity is very high, so I get great performance out of my solar water panels.

Thanks for the other comments on the 100k. I think I'll start shopping for a 400k or so.
 

beartoothweb

Well-known member
Aug 28, 2009
188
Pool Clown said:
beartoothweb said:
bk406 said:
The advantage of living here though is due to our altitude (4500')
I would call the manufacturer of the heater you choose, before you buy. Due to your elev. and the manufacturer, your heater may need to be re-jetted before it is shipped, to work properly.
Good advice. I'm only looking at ones that are in use "locally." Most that I've seen have a range of under 2500', then over 7000', so any in use up here should be jetted properly already.
 

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