To
understand how much heat a pool needs, first you must
understand how much heat it loses.
A pool loses heat at
night or in inclement weather at a quantifiable rate,
this rate is then used to determine the amount and type
of heat needed to keep a pool at a given temperature.
Heat Losses Swimming
Pool heat loss occurs primarily at the surface
where the evaporation of water accounts for this
loss. This is the reason for the tremendous net
effect of a pool cover.
Inground
pools lose only about 10% of the total losses
through the wall of the pool into the ground or
through the lines removing and returning water to
the pool in the normal course of daily filtration
cycles.
Pool Covers
reduce most if not all of the evaporative
losses from the pool when in use. With
this component of heat loss being 70% a
cover with a small R value can achieve as
much as a 75% reduction in heating costs
when used.
Heat Gains Swimming pools gain heat naturally
during the day by absorbing the infrared radiation from
the sun. An open pool gains almost twice the amount of
the sun's energy than a screened pool due to the blocking
effect of the screen enclosure, very similar to an
umbrella with holes in it. The net result in the Central
Florida area is a pool that is 6-8 Deg. F. warmer than
it's screened counterpart.
Temperatures for Screened Unheated Swimming Pool
(Assumes Central Florida, Unshaded Pool with average 4.5 ft. depth)
Solar systems can be sized
to gain anywhere from as little as 4 Deg. F up to as much
as 16 Deg. F before cost effectiveness becomes an area of
concern. The dilemma being that sizing for extreme
conditions when the sun's energy is relatively weak and
the outside ambient air temperatures are low means that
the collector area required becomes cost prohibitive. On
a 58 Deg. F. day swimming may not even be desirable, or
said differently even if the pool is warm- is anyone
in their bathing suit.
Saturday July 05, 2008 - 12:44 PM
