The output of a swimming pool heater is rated in a quantity known as BTU. To put this in perspective, a single BTU is capable of raising the temperature of 1lb of water by 1 degree (Fahrenheit). The higher BTU rating a pool heater has, the faster it will be able to heat your pool. There are two measurements that must be calculated in order to determine the correct heater for your pool: surface area and temperature rise.
- Surface Area: The more “surface area” that your particular pool has, the faster heat can escape from the water. Surface area describes the area on the surface of the water which is exposed to the air. Simple geometric calculations can be performed to determine the surface area of the pool. After the swimming pool heater heats the pool to the desired temperature, it must only add enough heat to compensate for the heat being lost to the air.
- Temperature Rise: Temperature rise describes the temperature difference between the ambient air temperature and the desired water temperature. The temperature rise will change throughout the year as the seasons change, but can be averaged to determine an approximate value. This value is used to determine an appropriately powered heater model.
- Heater Efficiency: The efficiency of a heater describes the amount of heat energy a heater transfers into the water for every BTU used. All heaters are required to have an efficiency rating of at least 78 percent.
Overpowered is Better:
It is prudent to select a heater which exceeds the minimal specifications as determined by your pool size. The bigger the heater is, the more rapidly it will be able to heat your pool. Buying one as big as you can afford will result in faster heating and a more enjoyable experience.
Types of Swimming Pool Heaters:
- Gas Heaters: Pool heaters are available which can run off of natural gas and propane. These gasses are burned within the heater to create heat. Selecting between these gasses is dependent on the availability and price of the gas, as well as the altitude of your home.
- Starters: All swimming pool heaters are equipped with a starter to ignite the gas. Two types of starters exist- the millivolt and the electronic start models. Millivolt starters consist of a pilot light which must remain lit at all times, similar to the starter in a gas water heater. Electronic starters are more convenient in that they do not have pilot lights which can be very dangerous to re-ignite. As such, electronic starters are more expensive.