pool heaters heat pool water to 80 to 85°F. Three types
of pool heaters are most commonly used-natural gas or propane
pool heaters, heat pump pool heaters and solar pool heaters.
Almost all conventionally fired pool heaters use natural gas
or propane. Gas pool heaters are most efficient when heating
a pool for short periods of time or for quickly heating a
pool, so they are best suited to pools that are not heated
on a regular basis. Unlike solar or heat pump pool heaters,
gas units can also maintain any desired temperature, regardless
of climate or weather. Solar pool heaters have very low operating
costs and are an effective use of available solar energy.
Heat pump water heaters can also cost less to operate, but
cost more to purchase than gas pool heaters.
Gas pool heaters are very much like instantaneous
water heaters. Water from the pool is pumped through a filter
and then the heater. Heat generated in the combustion chamber
is transferred to the water as it passes through the heater
and returns to the pool. In parts of California, NOx emissions
from pool heaters are regulated, which requires special low-NOx
pump pool heaters operate similarly to heat pump water heaters,
utilizing an evaporator coil, compressor and condenser to
extract heat from either indoor or outside air. As the pool
water passes through the filter and heat pump pool heater,
the extracted heat is transferred to the water and the heated
water returns to the pool. Higher efficiency heat pump pool
heaters use scroll compressors; standard units use reciprocal
compressors. The higher efficiency of heat pump pool heaters
is contingent upon outdoor temperatures above 45-50oF. Heat
pump water heaters can also draw heat from humid indoor air.
Some models also reheat the cooled air.
their water heater counterparts, solar pool heaters use collectors
to gather solar energy. As the pool water circulates through
the solar collectors, it picks up heat before returning to
the pool. An automatic or manual control valve can be used
to divert water through or around the solar collectors depending
on the temperature of the pool water.
Gas pool heaters are rated by Btu output. Outputs
range from 75,000 Btu to 450,000 Btu. Heat pump pool heaters
are rated by Btu output and horsepower. Standard sizes include
3.5 hp/75,000 Btus, 5 hp/100,000 Btus and 6 hp/125,000 Btus.
system contractors use worksheets and computers to size the
surface area of the solar collectors, taking into account
a number of factors including:
Length of swimming season
Average regional temperatures
Desired pool temperature
Solar resources at the pool's location
Collector orientation and tilt
Use of a pool cover