How to Use a Car Radiator for a Solar Water Heater

Written by eli laurens
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How to Use a Car Radiator for a Solar Water Heater
(Hemera Technologies/ Images)

Solar water heaters can dramatically reduce the energy required to heat water in a home. While most home-built systems use pipes or PVC tubing, using an automotive engine radiator can reduce build time. The concept is the same: by running water through a series of pipes exposed to the sun, the water is heated. Several units can be coupled together for increased water volume. The average backyard builder can turn a radiator into a solar water heater in about an hour.

Skill level:

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Things you need

  • Automotive radiator (without leaks)
  • Rubber radiator hose (universal fit x2)
  • Hose clamps
  • Screwdriver
  • Black spray paint
  • Soft hammer (rubberised mallet)

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  1. 1

    Gently tamp the radiator's heat fins with the hammer or mallet, so that they lay flat and close the gaps between them. In normal use, these fins would cool the water as it passed through the rows of tubes inside. All of the fins must be pounded flat, front and back.

  2. 2

    Spray the radiator with black paint, completely covering both sides, and allow it to dry. Several coats may be required for total coverage.

  3. 3

    Attach the radiator's inlet and output openings to the house's plumbing system using the universal radiator hose and the hose clamps. Tighten the hose clamps with the screwdriver by turning the screw clockwise. The pipes for the home will be close to the same size as the hoses coming from the radiator, and adaptors are available should the hose clamps not close tightly enough.

  4. 4

    Mount the radiator in a location where is in direct sunlight. As the water passes through the radiator's lines, the black metal structure will heat up, trapping the radiant heat and transferring it to the water.

Tips and warnings

  • Several radiators can be connected in series to increase water temperature and volume.
  • Use extreme caution when moving or repairing the radiator solar heater; the metal and water can be very hot.

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