How to Convert Solar Heated Water to Forced Hot Air

Solar energy can be captured and converted to useful household energy. Photovoltaic cells directly convert solar energy to electrical energy, but these systems are expensive. One of the most economical and efficient solar-energy collectors is a system that heats water with solar rays. The heat energy is transferred from the water into the homes' HVAC ventilation system, where the warm air can heat the home.

Solar energy collection system that heats water
3/4-inch copper water plumbing pipes and fittings
Extruded foam plumbing pipe insulation
Water-to-air heat exchanger
40-gallon electric hot-water heater tank.
Water circulation pump
12-3 ROMEX® electrical wire
Assorted hand tools, such as wire cutters, wire strippers, and screwdrivers
Propane torch
Plumbing solder

Instructions

- 1
  Construct a solar heat collection system on a home's roof, or southern facing exterior wall. These systems are available commercially or can be constructed from DIY materials and plans.
- 2
  Connect the plumbing line that leads out of the solar collection system to a secondary hot water tank in the home. The line out of the solar panel leads to the line into the hot water tank. The water for the solar collector is self contained, separate from the home's potable water.
- 3
  Mount a heat exchanger into the warm-air supply ducts in your home's HVAC system. Located in the basement or crawlspace, the furnace pulls cool air from the home, then uses a fan to blow the air back into the home once it is heated. The hot water to air heat exchanger, which looks like a car's radiator, is mounted into the HVAC system just above furnace, so that the fan blows air through the exchanger coils as the air head back into the home.
- 4
  Connect the water line out of the hot-water tank to the input of a hot water to air heat exchanger. New copper plumbing must be used to connect all the devices in this system.
- 5
  Connect the water line out of the heat exchanger through a water pump, and then back outside to the input side of the solar heat collector on the home's roof. The water now has a closed path, which travels through the system.
- 6
  Insulate all the copper plumbing lines inside the home with extruded foam pipe to prevent heat loss.
- 7
  Connect the thermostatically controlled circuit on the hot-water tank to the on/off switch on the water pump. The thermostat on the hot-water tank will close an electrical circuit when the water in the tank drops below the specified temperature. At this point, the pump will circulate water through a heat collector on the outside of the building, and return the heated water into the hot water tank. When the furnace kicks on due to cooling temperatures in the home, the fan will blow air through the heat exchanger, and transfer heat energy from the solar-heated water to the air to heat the home.

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