By Tom Soukup
When a facility is considering replacement of its standard efficiency pool heating equipment with new, high efficiency appliances, it is prudent to select a contractor who has a firm understanding of the unique challenges pool heating poses and knows the difference between conventional and condensing gas-fired appliances.
Mid-Atlantic and Northeast regions have variable shoulder seasons; and many pool companies serve major metropolitan areas, where it is common for facilities to keep outdoor pools and spas open for three seasons or even year-round. In such instances, the potential to reduce fuel consumption through heating appliance upgrades is tremendous.
What is a British thermal unit (BTU)?
Before diving into specifics, it is important to define what a BTU is. A BTU is the measure of energy needed to raise 3.8 L (1 gal) of water by 0.55 C (1 F), in one hour; 3.8 L (1 gal) of water weighs 3.8 kg (8.3 lb). To keep things simple, this article uses round numbers and accurate averages.
Relating the conversion to pools, it requires 833,000 BTUs to raise the temperature of a 378,541-L (100,000-gal) pool by 0.55 C (1 F). This does not account for evaporation or heat loss through the surface, shell, or associated piping.
Trying to determine the efficiency of a pool heating system by accounting for all the above is nearly impossible due to any number of variables, including outdoor ambient temperature, wind, ground temperature, etc. However, there is a much easier way to determine the efficiency of an existing pool heating system, and the potential energy savings that may be realized with a retrofit.
Calculating efficiency
Accurately quantifying potential fuel savings may weigh heavily into the decision of when to upgrade or whether to upgrade at all.
The following is to determine the actual fuel efficiency of existing heating equipment. This method works even if historic gas or liquified petroleum (LP) expenses are not known, which is often the case because the gas meter or LP tanks serving the system may also serve other portions of the facility for space heat, a commercial kitchen, domestic hot water production, etc.
