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Situated in the unheated garage, a thousand gallons of water
is a challenge to heat and keep warm during the cold winter
nights! Electrically there would have to be about 4-5kilo
watts worth of heaters. During the hot summer days with all
the lightings on full the challenge is opposite, keeping it
cool! Chillers to handle this kind of volume are very expensive
as well as crippling to run.
We installed a gas boiler rated at 80,000BTU together with
a titanium heat exchanger to provide the heating power. The
heat exchanger provides the thermal contact between the tank
salt water whilst acting like a radiator to the boiler on
the other side. The Titanium core is the only contact of the
tank water ensuring no contamination from the copper pipe
work of the boiler, and isolating the boiler from the corrosive
salt water.
This is what the heat exchanger looks like. The ports on
the sides are where the tank water passes through. In the
middle of the container is a block of titanium with holes
bore through. The ports on the top provide the connection
to the heating/cooling water
A little more design work, one 3-way valve, coils of thin
copper tubing burried 4-5' deep in the ground later... and
we converted the heating loop into a cooling loop via the
same heat exchanger. Cheap to run too!
How does it work? As it happens, the ground temperature a
few feet down stays at a constant 15deg Celcius all year round.
All we need to do is pass water through a conductive coil
(in this case we used about 20m of thin copper tubing) and
you dissipates the excess heat to the ground.
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The three-way valve directs the water through the boiler
for heating or through both the boiler and the ground
loop for cooling. The pump in the boiler provides the
circulation. A set of relays switches the boiler on (flame)
to provide heat and turn the valve to cut off the ground
loop - these relays are powered from one socket to call
for heat. |
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A second set of relays in the cooling mode to turn
on the boiler's pump but not fire up the boiler, and allow
the water to cycle through the ground loop. |
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