A friend of mine is considering adding a gas heater to his outdoor pool.
Without getting into too many parameters (size, location, usage etc) I just
want a few price points to get an idea of the magnitude of the cost others
are paying for energy (not the equipment).
To those who own heated pools:
If you would, please estimate how much more your energy bill is per month to
heat your pool and tell me what region you live in and if you heat it full
time or periodically so I can get a feel for the cost.
I assume he will also add an insulated pool cover at the same time if it
even gets done.
He is not a candidate for passive solar as he would like the option of
heating it in the winter if he wants (mild SF bay area winter)
NREL says 680 Btu/ft^2 of sun falls on the ground and 1050 falls on a south
wall on a 48.7 F SF January day, so a pool with an R1 cover with 80% solar
transmission would collect 544 Btu/ft^2 and lose 24h(T-48.7)/R1, which makes
T = 71.4 F. A reflective north wall might raise this to 90. And there's this:
That answer appeals to the engineer in me. Clearly under optimal conditions
Passive soalr is possible. Unfortunately weather is qute unreliable. A
couple days of rain followed by some cloudy days would cool the pool
significantly. I'll definately pass on the info
December is the worst-case month. That was an average December day.
An 80 F pool 6' deep might cool to (48.7x2+80x70)/72 = 79.1 after 2" of
rain. With a 6x62/R1 = 372 hour time constant, it would cool from 80 to
48.7 + (80-48.7)e^(-72/372) = 74.5 after 3 cloudy days.
Put them wherever you want them. Most people use a standard height
for resale value, but if you want to "personalize" your home, do
whatever you want. I dont think it would be allowed to put a switch
on the floor, and in wet locations (basements), there are limits
according to the code. But in a room, you can pretty much place them
any height on the wall.
The NEC is there to protect you from hazzards, but not from stupidity.
If you are happy with a wall switch being 6 inches from the floor, do
it. Your pets will be much happier when they can turn on the lights
The answer is a definite YES!, NO!, AND MAYBE!
Pool heat characteristics can be affected by a lot of things.
Surface area in relationship to depth.
When you run the filter.
Night time temperature.
Amount of sunshine into the pool.
Whether or not a blanket is put over the pool during night time or in windy
A pool can vary ten degrees a day considering a combination of these
So, to answer your question re: cost ............. A LOT! Gas prices
(whether propane or natural gas) is high. The heater would have to run a
lot during the winter to maintain a constant temperature. It would have to
be turned on hours in advance, depending on the heat gain rate of the pool.
As an example, my spa heats at 5 degrees an hour, and it is only 350
gallons. My pool holds 100 times that much water, so I can only guess how
many degrees per hour it would heat up, or how many hours per degree,
whichever is better.
Heating a pool is a losing deal. The heat will be lost to anything that is
cooler than the water.
How much does your friend want to pay? The only way to really find out is
to hook up the heater and go for it.
I use a solar heater, and that works great. It gives us a few extra months
of warm water, and during the summer, we have to turn it down, or the water
is not enjoyable to swim in. Don't discount solar, as it is free once it is
installed. The cost offset will be substantial, as a solar heater will cost
about $3k, and then after that there is no cost. If you burn $3k worth of
gas, you got nothing to show for it.
I live in Las Vegas.
"If you would, please estimate how much more your energy bill is per
month to heat your pool and tell me what region you live in and if you
heat it full time or periodically so I can get a feel for the cost."
Google yielded this DOE link that may help answer your question...
EERE Consumer's Guide: Estimating Swimming Pool Gas Heating Costs and
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