# Thread: How long does it take to heat a pool?

1. ## How long does it take to heat a pool?

So i've owned a non-permanent Intex pool in the past but we've recently bought a house with a permanent above ground pool which has a gas heater. I did not plumb the heater in when i opened the pool because the thought of heating a pool in WI climate rings \$\$\$\$ in my mind. But after a somewhat chilly dip into the pool this past weekend, i'm reconsidering my thoughts.

The pool is a 24' Dougboy that's around 45" of actual water depth.
The heater is a gas Hayward unit ( i think the model is a 210).
Temps lately have been around upper 70's during the day and upper 50's through the night.
I do have a blue solar cover on the pool at all times.

So the question is, how long does it take to raise the pool temp say 5 degrees and what sort of money does it cost to do this with the gas units? I know there are alot of variables but just trying to understand what i'm roughly looking at...is it \$20 bucks every time i flip the heater on the night before a pool party or is it more/less?

Thanks
Matt

2. ## Re: How long does it take to heat a pool?

3.14159 * (24/2)^2 * (45/12) cubic feet in gallons is 12690 and in pounds of water (8.33 pounds per gallon) is 106,000 pounds. The Hayward H210 is 210,000 BTU/hr input and I don't know it's efficiency but let's say it's 85% for 178,500 BTU/hr output. It takes 106,000/178,500 = 0.59 hours or 36 minutes to raise the water temperature by 1ºF if there were no heat losses (i.e. starting from equilibrium temperature with the air). 5ºF would take 3 hours.

As for cost, Wisconsin gas rates are 21 cents per Therm (100,000 BTU) so running the heater for 3 hours would cost 3*(210,000/100,000)*0.21 = \$1.32

3. ## Re: How long does it take to heat a pool?

Note - If Chem geek replied, ignore mine!

Rough Math = 1 btu will raise 1 pound of water 1 degree. Your pool = 6,423 gallons x 8.34 lbs/gallon =~53,500 lbs of water.

I assume the 210 model is 210,000 btu's. That means the heater will add ~210K btus per hour. And you will 53,500/210,000 = 3.9 degrees per hour or ~1.3 hours for 5 degrees. Of course that is considering 100% efficiency (closer to 80%) and no heat loss through evaporation. Which would be limited by the cover. That's actually a large heater for the pool, which is nice.

Your cost would be around: 210,000 X 1.3 (hrs) = 273,000 btus or 2.73 therms. There are 100K btus per therm of gas. Just look at your recent gas bill and multiply your cost/therm * 2.73 therm to get your approximate cost. Dont forget to add both gas cost and delivery costs.

4. ## Re: How long does it take to heat a pool?

I think your pool size is off. Even PoolMath with 24' wide (diameter) and 45/12 = 3.75' deep gives 12700 gallons (I used 12690 in my calculation).

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