Looking for savings in heating domestic hot water? Sometimes combining two systems can result in considerable energy savings. You may want to take a look at the combination of a solar water heater outside and a tankless or on-demand water heater inside.  In a recent study conducted by the National Association of Home Builders Research Center, this combination showed a two-thirds savings in electricity compared with a standard electric tank system.

The roof mounted, batch-type solar water heater contains copper tubing to store up to 40 gallons of water.  The solar unit is connected to a tankless water heater with its thermostat set at 130 degrees F.  The water heater only kicks on when the temperature of the solar heated water falls below the 130 degree level, usually for short time periods, if at all.  Over a period of 14 months the solar-assisted on-demand system used an average of 66 percent less electricity.  For a home using about 50 gallons of water a day, the system has an estimated 13-year payback. As electricity rates rise this time period could shorten.

To download the a copy of the report, visit www.toolbase.org/pdf/fieldevaluations/InterimREportJWMiller.pdf.