What's the Cost to Run A Pool Heater

Anthony10124

New member
Jan 4, 2021
1
Claremont
Hi,
I am trying to figure out how much it will cost to heat my pool for a weekend, to get a ballpark estimate. I have a gas heater (Purex Triton Minimax 250) and trying to see how much I am in for before firing it up. Here is my data:

pool size = 15' x 30'. Water temp = 70, would like to have it 90. From this website it says I need approx 108,000 BTU's to raise the water temp. 20 degrees for this pool:


I assume this means it takes 108,000 BTU's to get the temp up 20 degrees, at that point the heater turns off (and the pool starts to cool :)

From the below website it says there are 1080 BTU's per cubic foot of gas:
http://www.appleheating.com/heating/fue ... calculator

This gives a requirement of 100 CCF.

In my area gas prices are running about $0.7 / CCF from below:

http://www.centerpointenergy.com/servic ... prices/HO/

That would be a total of 100 * 0.7 = $70, to heat my pool by 20 degrees. Or to raise it 10 degrees, $35.

1. Does this seem legitimate? Am I missing any basic steps here?

2. Once pool is at 90, how much does it cost to maintain this temp for 8 hrs, or for 24 hrs?

3. My heater is rated for 250,000 BTU's per hour. How can I determine how long it would take to raise the temperature of the water - eg. 1 hour, 8 hrs, etc?


Thanks for any help you can provide. My next step is to research solar blankets :)
 

skimmerswimmer

Well-known member
Jul 30, 2013
401
Long Island, NY
My pool is much bigger at 33k gal and my heater is 335k btu which costs around $4 per hour to run. The heater will raise the water temp about 1 degree per hour, a little more if the sun is out and there is little to no wind. If I had to raise my pool by 20 degrees, it would cost about $80.

The pool will usually lose around 3-4 degrees overnight, sometimes more if it gets really cold.
 

jseyfert3

Silver Supporter
Bronze Supporter
TFP Guide
Oct 20, 2017
1,453
Southern WI
Pool Size
15000
Surface
Vinyl
Chlorine
Liquid Chlorine
@Anthony10124 how many gallons is your pool? Also welcome to TFP!

Something’s not right with your math, let me know gallons and I’ll plug a couple rough numbers after dinner.
 

Cluckr7

Well-known member
Jun 19, 2020
89
Texas
Pool Size
20000
Surface
Plaster
Chlorine
Salt Water Generator
SWG Type
Jandy Aquapure 1400
A heater's rating is in BTU per hour. One BTU is the heat needed to heat one pound of water by 1 degree F. A gallon of water weighs 8.34 pounds. A heater's efficiency is maybe 80%.

So you can estimate the BTU you need can be calculated as "desired temp increase * gallons * 8.34 / 0.8". For example, a 20k pool raised 20 degrees will need approximately 20000 * 20 * 8.34 / 0.8 = ~4.2 million BTUs.

You can estimate the time needed by dividing the BTU needed (calculated above) by your heater's BTU rating. This is in hours. For example a 400kbtu heater would take ~4200000/400000 = 10.4 hours. This is just an approximation as there's added complexities of heat xfer, but in my experience it gets you pretty close.

You can figure out the cost by converting BTU needed to cubic feet as you've already done. This is just to raise the temps, not to maintain. Maintaining temps depends on how much cooling you'd get (function of air temps, wind, humidity, etc), but you can probably assume a few degrees of cooling per day and use the same calculation.
 

Cluckr7

Well-known member
Jun 19, 2020
89
Texas
Pool Size
20000
Surface
Plaster
Chlorine
Salt Water Generator
SWG Type
Jandy Aquapure 1400
Also i'm guessing ccf means 100 cubic feet, not 1 cubic feet.
 
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1poolman1

In The Industry
Jul 14, 2014
66
Sacramento
What you are missing in your information is the volume of your pool. A 15 X 30 pool that is averages 3' in depth has much less water (10K gal +/-, 80k lb. of water) than one that averages 5' (17.5k gal +/-, 140k lb. of water).

Those old MiniMax heaters were about 80% efficient giving you 200k btu in the water per hour. That would raise your 10K pool about 2.5 degrees per hour or your 17.5k pool about 1.4 degrees per hour. Your heater will consume 250 cubic feet of gas per hour +/-. You can figure the cost from this.
 
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