An indoor pool — with this system — can
actually pay for itself in reduced utility bills!
by Rae Donaldson
Five years ago, when my husband and I installed a 16' X 32'
vinyl swimming pool in a room enclosed in translucent
fiberglass, we weren't being merely self-indulgent. I
needed that "luxury" for therapy, you see, since I'd
earlier developed a muscular/neurological disease that
only a daily routine of swimming and pool exercise
would help to control.
Of course, I'll be the first to admit that having a heated
pool was a real treat, because we live on the cool Oregon
coast where — during much of the year — the
ocean water is icy enough to turn swimmers blue. And
because the indoor facility was attached to our garage, we
could even get to it without braving our winter rains,
which occur often enough to dump 60" to 90" of moisture on
our part of the state each year.
At first, we were quite able to afford the extra energy
consumed by the pool's electric water heater, but —
little by little — the utility rates in our area
climbed. By January of 1981 we were paying 43% more for
electricity than we had when the pool was built . . . and
our city announced an upcoming 25% annual increase. Since
runaway inflation was already playing havoc with our
retirement budget, we simply couldn't handle those
increasing costs. Yet I didn't want to sacrifice my health
or take on the medical expense of outside therapy,
so I decided to look for an alternative way to heat our
A FORTUNATE MEETING
To my dismay, research soon revealed that oil heat was even
more expensive than electricity, and natural gas isn't
available in our area. Then, following the suggestion of
several friends, I investigated solar heating methods, only
to learn that we'd have to spend $4,000 to $12,000 for a
system that would still need frequent backup in our
commonly cloudy area.
In short, I was just about to give up when I was introduced
to a young man named Michael Lindsay, who — with his
father — owns the Lindsay Furnace Service (Dept.
TMEN, 1239 Andrew Street, Coos Bay, Oregon 97420). Mike was
intrigued by our problem . . . enough so that he offered to
come to our house to study the situation, at no cost to us.
Suffice it to say, we accepted his offer. Mike came out and
— after a lot of measuring and muttering to himself
— finally announced, "What you need is a heat pump."
That was an idea we'd never considered, so our expert set
out to explain what he had in mind.
"The heat pump concept dates back to the 1850's," he told
us, "but efficient, well-serviced models weren't developed
until after the 1973 oil crisis. The principle is basically
the same as that used in a refrigerator, where heat is
removed from inside the box and discharged into the room. A
home air conditioning unit performs in a similar manner, by
removing heat from the house and discharging it outside.
And if this operation is reversed — if heat is
removed from the outdoors, concentrated (in effect), and
funneled into the living space — you have what's
commonly called a heat pump.
"In your case, there's a considerable heat gain in your
fiberglassed enclosure, even on cloudy days, and that
warmth can be efficiently transferred to the pool. I
suggest, though, that instead of the conventional airsource
heat pump, we install a water-source model designed to
utilize the warmth stored in wells, lakes, and streams.
This type is approximately three times as energy-efficient
as an electrical heating system. It's similar in operating
principle to an air-source unit, but exchanges heat with
water rather than air. In fact, we can use the warmed air
in the pool room to heat your swimming pool, then —
while we're at it — we can use the water in your pool
to help warm your house!"
As you can imagine, that last bit of news really made us
sit up and listen, and Mike — seeing our interest
— went on enthusiastically: "Since the swimming pool
provides a perfect heat sink, with a good amount of thermal
storage capability, I'll design a reverse into the system.
Heat from the pool can then be extracted and transferred
— through air ducts — to your home. This will
cause the pool temperature to drop by only a few degrees,
and as soon as the house is up to temperature, you can go
back to heating the pool."
Mike's proposal was pretty attractive to us, especially
since we were depending on electric baseboard heat in our
house . . . and that cost, too, was getting out of hand.
After making a few more calculations, Mike came up with a
$5,000 estimate for the dual-purpose installation. We
thanked him and told him we'd be in touch. Then we talked
it over . . . juggled our budget a good bit . . . studied
brochures on heat pumps . . . and finally decided to
install the suggested system.
AN IDEA MADE REAL
Two days later, Mike and his assistant Bill arrived with
our heat pump. The 22" X 27" X 44" unit is similar to an
electric furnace in appearance. But before it could be
hooked up, holes had to be cut — through concrete
block — from the garage to the pool room. After that,
the return and supply ducts were mounted side by side in
the wall. Next, Mike designed a motor-driven damper and
installed it in the ductwork to direct the air.
"When the pool needs heat," he explained, "the flow pattern
will be such that heat from the air in the pool room will
be transferred to the water. Then, when the thermostat
signals that your living quarters require heat, the airflow
will switch to the house circuit, and water from the pool
will be delivered to the pump's heat exchanger, where the
house air will pass over it and warm up."
Finally, aquastats equipped with sensors were plumbed into
the pool under a deck board. These cut in the heater
whenever the water temperature drops below 80°F, which
I find a very comfortable temperature for swimming.
We were quite excited — and just a little nervous
— when Mike turned on the heat pump. Bill held a
thermometer in the pipe that began shooting the warmed
water into the pool, and the reading was 97°F. What's
more, the rate at which that water was being pumped
(recirculated) measured nine gallons per minute. The system
was a success . . . in fact, it exceeded even Mike's
FROM POOL TO HOUSE
With the first part of the plan functioning perfectly, it
was time to arrange for transferring heat from the pool to
the house. To do so, the men constructed ducts (heavily
insulated to insure efficiency and quiet) and strapped them
to the basement ceiling, using turning vanes at any 90°
Then Bill cut a large outlet in our entry hall, upstairs,
and covered it with an attractive grille. A return duct in
the wall of the stairwell leading to the basement allows
circulation of air. We can, anytime we choose to do so,
install more ducts to move warmth into the bedrooms and
baths. We can even add an attachment to the heat pump that
will preheat our domestic hot water supply, and —
budget allowing — we've decided to try that next. (If
you live in a sunnier climate than we do, you may be
interested in knowing that Mike is sure a system like ours
could be used quite effectively with a solariheated
It would be advantageous to have a larger pool . . . one
with the volume to store an adequate amount of heat for our
house during long periods of inclement weather. As it is,
we did occasionally have to fall back on our electric heat
last winter . . . but we're not complaining! After all,
this heating system decreased our utility bills —
compared with the previous year — by half during the
rainy winter months . . . and by two-thirds during