Size of Heater

[jklym]

We are installing a 15x34 fibergl*** IG. It is about 17000 gallons. What size heater do we need? Will 200K BTU do the trick? Is there value in "bigger is better"?

Thanks-

Jeff

[SeanB.]

We are installing a 15x34 fibergl*** IG. It is about 17000 gallons. What size heater do we need? Will 200K BTU do the trick? Is there value in "bigger is better"?

Thanks-

Jeff

Ours will be just over 13,000 gallons and they are putting in a 250,000 btu heater, if that helps - not sure how they determined what size to use though.

[sjkader]

this is taken from the dept of energy website. Hope it helps.

Sizing a Gas or Heat Pump Swimming Pool Heater
You should have a trained pool professional perform a proper sizing analysis for your specific swimming pool to determine pool heater size.

Sizing a gas or a heat pump pool heater involves many factors. Basically, a heater is sized according to the surface area of the pool and the difference between the pool and the average air temperatures. Other factors also affect the heating load for outdoor pools, such as wind exposure, humidity levels, and cool night temperatures. Therefore, pools located in areas with higher average wind speeds at the pool surface, lower humidity, and cool nights will require a larger heater.

Gas pool heaters are rated by Btu (British thermal unit) output. Outputs range from 75,000 Btu to 450,000 Btu.

Heat pump pool heaters are rated by Btu output and horsepower (hp). Standard sizes include 3.5 hp/75,000 Btu, 5 hp/100,000 Btu, and 6 hp/125,000 Btu.

Calculating Approximate Size
To calculate an approximate heater size for an outdoor swimming pool, follow these steps:

Determine your desired swimming pool temperature.

Determine the average temperature for the coldest month of pool use.

Subtract the average temperature for the coldest month from the desired pool temperature. This will give you the temperature rise needed.

Calculate the pool surface area.

Use the following formula to determine the Btu/hour output requirement of the heater:


This formula is based on 1º to 1-1/4ºF temperature rise per hour and a 3-1/2 mile per hour average wind at the pool surface. For a 1-1/2ºF rise multiply by 1.5. For a 2ºF rise multiply by 2.0.

[tenax]

beyond the responses above..you have to ask yourself:

-how quickly you want the pool to heat up?
-will you use it to gain a longer swim season?


i have for 12,000 gallons a 125,000 btu natural gas. it will heat up about a degree per hour on a 70 plus degree day..but overnight right now for example with colder air temps, it only heats up about 1/2 to 2/3 a degree per hour.

i had no interest in extending my season beyond current (mid may to mid sept) as once the air temp is below 70 the kids have no interest in swimming even if the pool is hot (air feels too cold to them when they get out)

i would say my 125,000 btu heater for my pool size and situation is just enough. from what i understand a bigger heater will simply heat up the pool quicker the bigger you go..in turn, running for a shorter cycle.

the problem i ran into is heaters cost a fortune in canada compared to the us, so i bought from the u.s. even so, the difference in price for a 125,000 btu to 175,000 btu was about 50% more and i didn't feel i would get my money's worth for the bigger unit..frankly, when i reviewed prices at the places i was looking at to buy, for another 10% more cost going from the 175K to a 250K, i would have gone that route..

check the prices out carefully, do your research, figure the bang for your buck.

[thepoolman1]

When you buy a larger heater you are paying for convenience in the form of a faster heat-up. Just remember to size both the gas line AND the meter (if natural gas) to the heater or the larger heater won't work properly (if at all) and, if it does light, can be damaged by low gas pressure.