Hooking up a Pool or Spa
A heat exchanger should be used to transfer heat from the outdoor wood furnace to the
pool or spa. You don’t want old dirty furnace water mixing with nice clean pool water!
Never use a brazed plate heat exchanger for a pool as the chlorine will destroy it in
short order. ALWAYS use a Stainless Steel shell and tube heat exchanger for this
purpose.
If the spa isn’t too big and you are NEVER going to use the built-in domestic hot water
heat exchanger to heat your hot water, you can utilize that for your spa or hot tub.
We have tried many different ways of hooking up pools with different systems;
thermostats, etc., where the pump goes off and on to control the water temperature.
The main problem is that when no heat is being extracted out of the furnace, the water
can boil. It is best to utilize a system whereby the pump runs all of the time so that the
water can’t just sit stagnant in the furnace, overheat and boil.
The thermostat is connected so that it controls a 3-way valve. When the water needs to
be heated up, the circulating water is routed to the heat exchanger. When the water
reaches a preset temperature, the 3-way valve bypasses the heat exchanger and sends
the water back to the outdoor furnace, keeping the water circulating. This system works
the best. A kit is available with complete instructions and every bit and piece needed
(including wiring for the controller), to make the installation super easy! Diagram by
Alternative Heating & Supplies.
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