- Call used appliance stores to locate a junked refrigerator. Ask the store to cut off the grill close to the large coolant base, remove the Freon and hold the grill for pickup. Be sure to ask for and keep the mounting brackets.
- Determine how much wood and rubber you need based on the size of your refrigerator back. The frame of an old couch can provide ideal wood to frame your water heater. Measure the wood 6 inches longer and 2 inches wider than your grill. You need four pieces of each size. Find a discarded rubber doormat to use for your water heater backing and cut it so it's 2 inches larger than the grill all around.
- Purchase a piece of window glass the same size as your rubber mat. Stop by the pet store for the air pump hose..
- Paint one of the 5-gallon buckets black and seal the top with duct tape. Leave a hole in the top just large enough to allow the air pump hose to pass through. This acts as insulation and keeps the water warmer longer.
- Assemble the top and bottom frame, using wood screws, so that one fits evenly atop the other. Cut notches in the bottom board of the top frame to accommodate the in and outtake pipes on the refrigerator grill, but do not attach it yet. Set the frames aside.
- Cover one side of the rubber mat with aluminum foil to reflect light and heat. Fold the ends under and secure the foil to the mat. Seal the overlap gaps with duct tape.
- Set the rubber mat on the bottom frame foil-side up. Set the top frame on the rubber mat and make sure the top and side of all three parts are square. Begin at the corners and drive long wood screws through the top two layers and well into the bottom frame. Then drive screws at 2- to 3-inch intervals to ensure that your water heater frame is solid.
- Place the refrigerator grill in the frame with the in and outtake pipes at the unfinished end of the top frame. Use the mounting brackets to attach it to the backing. Ensure that it's tight enough to prevent slippage. Set the notched board in place. Use wood screws to attach it to the rest of the frame.
- Cut the air pump hose so that one piece is about 1 foot longer than the other and fit it over the grill's in and outtake pipes, with the longer piece on the intake. Wrap the junction with duct tape to ensure a tight seal.
- Lay the glass on top and mount it to the frame with duct tape.
- Position your completed water heater panel at an angle where it will catch the most sun.
- Fill the unpainted 5-gallon bucket with cold water and put the intake tube in it. Place the painted bucket so that it is higher than the unpainted one; this creates a gravity siphon.
- Suck on the outtake tubing to start the water flowing. Once the flow begins, push the tubing into the hole on top of the bucket. It takes approximately two hours for your simple heater to warm 5 gallons of water.
Things You Will Need
- Refrigerator back
- Rubber mat
- Hand saw
- Aluminum foil
- Duct tape
- 6-foot air pump hose
- 2 5-gallon buckets
- Mounting brackets
- Wood screws
- Black paint
- Use brackets to mount the glass to the frame for prolonged use. The duct tape begins to peel after several days in the sun. Many local dumps allow foraging; if yours does, its an excellent place to find a discarded refrigerator.