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By Robert C. Herman
~Illustrations~
(Continued)
How long will it take to heat the water? That depends
on a number of factors, including the size of the collector, the efficiency
of the tub insulation, amount of sunshine, etc. On a sunny, mid-summer
day in Colorado, if I fill my tub with tepid water at 10 or 11 am, the
water temperature rises to 110 degrees within two hours.
After the initial heating, the collector only needs to
maintain the water temperature. From the second day on, your biggest concern
will be how to keep the temperature cool enough for comfort. With a reasonable
amount of sunshine and a well insulated tub, your water temperature can
become much too hot- more like a crock pot than a hot tub- and you'll
have to cool it down before you can climb in. You'll need to expiriment
with this, but I have found three low tech ways to control the heating
process:
- Cover the collector surface. I have used bamboo shades
to partially cover the collector, thus reducing its solar input and
its water heating capacity.
- Uncover the tub. Open the lid and remove the floating
insulation to allow heat to escape from the water.
- Partially close the "cold" side valve to reduce the
flow rate of heated water.
Of course, you can stop the circulation, thus the heating,
by closing both the "cold" and "hot" valves. This will prevent the water
in the tub from getting any hotter, but will increase stratification in
the tub, with the hottest water near the top and the cooler water at the
bottom.
IMPORTANT: Whenever the "hot" side
valve is closed, the manual safety (pressure release) valve must be open,
or an automatic pressure relief valve must be in place. Water + heat +
pressure = steam, and that steam must be released. An automatic safety
valve, replacing the human element, is better than a manual valve.
A good thermometer is needed to monitor water temperature
in the tub. Avoid the standard pool or spa thermometers, which only read
up to 120 degrees (If left "full on" my tub can heat up to 150 degrees
in two days). I recommend a chef's thermometer (about $5), with a dial
that read from 0 to 200 degrees F. If you use floating insulation in your
tub, simply insert the pointed end of the thermometer probe through the
styrofoam into the water. Otherwise, make a small raft out of foam, stick
the thermometer through it and float it on the water surface.
Ideal water temperature is a matter of individual preference.
I find that 102-105 degrees is good for prolonged soaking and meditation,
while 110 degrees provides the kind of deep therepeutic heat that turn
knotted muscles into putty. Above 110 or so, it's time to throw some carrots
and potatoes into the water.
Our household uses untreated spring water, which I haul
300 gallons at a time from a source several miles away. Since I have to
truck in every gallon I use, I like to optomize my water use. At the same
time, I am disinclined to add pool chemicals to my tub water, not will
I get involved in PH testing or any other slavish rituals. As a result,
though I hate to waste water, I have to change the tub water frequently.
My solution to this dilemma is simple. I dug a hole and
sunk a barrel in the ground just downhill from the lowest point in the
system. Into the barrel I dropped a small centrifugal pump with a float
valve. A length of garden hose runs from the collector's drain valve to
the barrel.
About once a week, I drain the water out of the system
and into the barrel. The pump sends the water to the various garden areas
to irrigate vegetables and flowers. Thus the water is used twice. Nothing
is wasted and no chemicals are used.
You can extend the useful life of your tub water by fitting
a filter of some sort to the cold water outlet n the bottom of your tub.
The neck and top section of an appropriate-sized plastic bottle, press-fit
into the outlet, will work. Cut a small piece of aluminum or brass window
screen material (steel will rust) and mold it into the bottle neck. Back
that up with a wad of filter material and you will catch much of the junk
that ends up in the water after a few soaks. Be sure to check the filter
frequently, and replace it as needed.
There is nothing like relaxing in your tub at the end
of a long day of hard work, or soaking for a half hour at midnight under
the milky way. The hot water relaxes your muscles, works out the knots,
and soothes the soul. A leisurely soak in the tub allows you to slow down
and remember why you chose this self-sufficient lifestyle in the first
place. Let other people pay thousands of dollars to the spa guy. Do it
yourself, for peanuts.
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