Greetings all!

I have never had a pool or spa before, but am considering getting one
of each , so I could use some advice regarding energy efficiency/cost
of two different paradigms we are considering.

The pool woul be an in-ground fiberglass pool like the Viking Freeport.
It would be covered with an automatic cover except when in use, and I
don't think we will be heating it all that much, really. We live in
Southern California, USA, and will probably use the pool mostly in the
summer-ish months when it is pretty warm anyway. In any case, my
question really concerns the spa; in either paradigm below, assume the
spa would be used about 15 nights month, and that the spa would have a
fully insulated cover:

One paradigm is to have the pool installer also put in a fiberglass,
in-ground spa which would be (a) connected to the pool's
heating/filtering system; and (b) heated with propane.

The other paradigm is to get a portable spa like the Marquis Mirage;
this would (a) not be connected to the pool heating/filter system; and
(b) would be heated with electricity.

The cost advantage to the first paradigm is that we would use propane.
The cost advantage to the second paradigm is that the spa water would
tend to stay pretty warm since it would not be mixed with the cooler
pool water during filtration.

We like the looks of the in-ground spa much better (it would be raised
up around 18 inches, so it isn't totally in the ground). We have
gotten conflicting estimates as to how much it would cost to heat the
spa in either the (a) "heat up with propane prior to each use" model
or the (b) "pretty much alway keep hot with electricity" model. Can
anyone suggest any rules of thumb for calulating the costs of heating
the spa? If anyone is roughly familiar with the relative pricing of
propane vs electricity in California, that would be particularly
helpful. Is it the case that...regardless of the relative cost of
propane vs. electricity...one of these two paradigms is universally
regarded as significantly more cost/energy efficient?

Any illumination or opinion on this matter is greatly appreciated!

Chuck

I have a small outdoor self contained spa. I tend to keep it set low,
at around 80 or so in winter, maybe 95 in summer, then turn it up to
104 or so prior to using it, which might be a couple times a week. I
haven't measured what it costs to run, but I don't think it;s really
noticeable in the average home electric bill, meaning it's dwarfed by
the electric used for air conditioning in summer or even electric for
running the furnace blower in winter, etc. If I had to guess, I'd say
it may average $15-20 a month or so here in NJ. In CA, it obviously
would be even less. A bigger spa kept at operating temp all the time
of course would use somewhat more.

With the propane/inground system, I would be concerned about two
things. The first would be mixing the spa water with the cold pool
water that you indicated. I've never seen one of these, but I would
think you would want it so that did not happen, as it sounds like it
would waste a lot of heat, especially in winter. The other concern
would be how well insulated the inground spa is. Never saw that
either, but it should have some kind of decent insulation against the
earth. Those two would have to be weighed against the typical lower
cost of propane heat vs electric. Another factor that might favor
propane is that I'm sure that type of heater will put out a lot more
heat in a short period. That would allow you to keep it set low if
you wanted, yet turn it up and have it hot and ready to go quickly.
With 240V systems, a 6KW heater is typical. To get mine from 80 to 105
would take at least a couple hours.

chuck wrote:

stuff clipped


One paradigm is to have the pool installer also put in a fiberglass,
in-ground spa which would be (a) connected to the pool's
heating/filtering system; and (b) heated with propane.


Update: I did not fully understand an element to the above paradigm
when I initially posted my query, but have cleared things up after
meeting with our pool contractor yesterday. I thought the hot spa
water and cool pool would be freely mixed with each other during
filtering, but of course what really happens is that a three-way valve
in the piping system essentially keeps the spa water and pool water
mostly separate (except for whatever water happens to be in the pipes
when the valve is shifted from spa to pool or vice versa). This makes
more sense, and I am now more sanguine about the in-ground spa which
shares the pool's heating/filtering system.

Still, I am always interested in absorbing more advice and opinions!

Chuck