Build Simple, Do-It-Yourself Solar Water Heater

QUESTION: I would like to build an inexpensive solar water heater to save energy and protect the environment. I can’t afford to buy a large contractor-installed system. What is the simplest do-it-yourself system?

ANSWER: For less than $100 in materials and a weekend’s work, you can build an effective solar water heater yourself. On average, this simple type of solar water heater can reduce your water heating costs by up to 25%. It mounts next to your house on the ground with no roof collectors.

This simple type of solar water heater is called a “batch” design. It is basically a water tank inside a box with a clear top. As the sun shines in the box on to the tank, the water inside it is heated.

This heated tank of water is used as a preheater for your regular water heater. The water coming into your existing gas or electric water heat runs through the solar water heater first. On a bright sunny day, the water from the solar heater can be warm enough so your existing water heater won’t have to come on at all.

Depending on how much you plan to spend on materials and how much solar hot water output you want, you can vary the complexity of the solar design. A two-tank unit produces more hot water. Nighttime insulation increases the overall efficiency and output.

You can greatly reduce the cost by finding a discarded water heater tank in good condition. Check with a local plumber. Strip it down and paint it flat black to absorb more of the sun’s heat. Special extra-efficient solar paints for the tank and special clear covers for the top are available.

In its simplest form, just make a wooden box using cheap 2x4 lumber and plywood and leave the top open. Line the inside of the box with foil-faced rigid insulation. Mount the painted water tank in the box and cover the top with an old glass storm door or storm window. Tilt the box up toward the sun and run the inlet and output pipes to your existing water heater.

A more efficient design uses an insulated box and insulating lids with reflective inside surfaces. When open, these lids reflect additional sun’s rays through the clear top and front covers on to the water tank inside the box. Foil-faced rigid insulation is effective for the reflective covers.

When the sun goes down, you should close the front and top insulating covers. This retains the heat in the water for many hours.

You can write to me for Utility Bills Update No. 243 showing detailed do-it-yourself instructions, diagrams and materials list for making the more-efficient solar design, list of manufacturers of special solar materials and a plumbing layout schematic. Please include $1.50 and a self-addressed business-size envelope and mail to James Dulley, Los Angeles Times, 6906 Royalgreen Drive, Cincinnati, Ohio 45244.

Automatic Setback Thermostat Lags

Q: I use an automatic setback thermostat for both my central heating and air-conditioning systems. In the winter, it seems to heat up quickly, but in the summer, it takes a long time to cool after setback. Why?

A: Setting back your thermostat can save a significant amount on your annual utility bills without a great sacrifice in comfort. Since the heating output of most furnaces is greater than the cooling capacity of most air conditioners, it takes longer to re-cool your house than to reheat it after a setback period.

One option is to install a new computerized thermostat. It remembers how long it took to re-cool your house last time. It starts the cooling cycle early enough to be at the desired cool temperature at the proper time.

Letters and questions to Dulley, a Cincinnati-based engineering consultant, may be sent to James Dulley, Los Angeles Times, 6906 Royalgreen Drive, Cincinnati, Ohio 45244.

DR, Water Heater Solar batch water heater is easy to make yourself.