How long does it take to heat a pool?

[willie1280]

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

 

[chem geek]

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

 

[Pool Tool]

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.

 

[chem geek]

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).

 

[willie1280]

Since i finally got the heater to actually work, i'm reviving an old thread!

My heater is actually a H150 model, so it's 150k BTU.

So based on Chem Geek's equation, at 85% efficency i'm running 127,500 BTU/hr. This would take 50 minutes to raise the pool temp by 1 degree.

My current gas rate per therm is $0.85 ($0.26 per therm for distribution and $0.59 for the actual gas).

With all that, it looks like i calculate it to cost $1.28 per hour that i run that heater.

So to get the temp up say 10 degrees it's gonna cost me roughly $13. But once it reaches temp, the cost per hour should go down to maintain temp....right?

 

[PoolGate]

Since i finally got the heater to actually work, i'm reviving an old thread!

My heater is actually a H150 model, so it's 150k BTU.

So based on Chem Geek's equation, at 85% efficency i'm running 127,500 BTU/hr. This would take 50 minutes to raise the pool temp by 1 degree.

My current gas rate per therm is $0.85 ($0.26 per therm for distribution and $0.59 for the actual gas).

With all that, it looks like i calculate it to cost $1.28 per hour that i run that heater.

So to get the temp up say 10 degrees it's gonna cost me roughly $13. But once it reaches temp, the cost per hour should go down to maintain temp....right?

Depending on outdoor temps and whether you put a solar cover on the pool every night you'll lose heat at night. With no cover and the heater off and outside temps in the 60s, I lose around 5 degrees overnight.

 

[CJadamec]

Overnight heat lose can vary drastically based on local weather conditions. I can lose anywhere from 2-10 degrees overnight and that's with my cover on. With the cover off its between 2-20. So the questions of how much it takes to maintain the pool is very dependent on your local weather.

If I had to average your costs out I would say 5-8 dollars a day to maintain your pool temp based on losing 5 degrees a night with a cover on. Some days it will be more some days less.