Inside Hybrid Water Heating

Every house needs hot water, of course, but how you achieve that year-round, 24/7 requirement is changing. Demand for more energy-efficient water heating equipment and a higher level of homeowner comfort and convenience combine to call for new and better solutions.

Green-minded pros are turning to so-called hybrid systems — specifically combining propane-fueled equipment and solar hot water systems — to supply domestic hot water.

Though not yet mainstream, these combination systems leverage the respective advantages of propane-fueled water heating equipment and solar thermal collectors to achieve the optimum combination of energy and cost efficiencies, reliability, and convenience.

A typical scenario using a hybrid approach might look like this: To offset the cost of electricity to heat water for a variety of domestic uses, a remodeler installs ground- or roof-mounted passive solar thermal collectors as the primary method for water heating. Heat from the sun is transferred to (or exchanged with) the home's potable water as it is pumped through pipes within the collectors, then stored in a tank until it is needed by a hot water-using appliance or fixture, such as a clothes washer or faucet.

Solar thermal technologies have improved dramatically from a generation ago. Today, the components are far more efficient, integrated into the roof finish, and able to be supplemented with more traditional water heating equipment to deliver greater reliability, convenience, energy use, and cost savings.

However, a solar-thermal solution works best when it is supplemented (or combined) with a more traditional water heating system. To that end, energy-conscious professionals also install high-efficiency propane or natural gas units — and even tankless water heaters — to supply domestic hot water when the solar thermal collectors fall short, such as on cloudy days and at night.

In this scenario, the cost to power these supplemental or auxiliary propane-fueled water heaters is less than if they were used as the primary equipment, and certainly if they were powered by electricity.

The result of this hybrid approach is a domestic water heating system that uses multiple energy sources to their optimum efficiency, depending primarily on a renewable resource (solar) but with an affordable, reliable, and clean-burning backup (propane) to deliver comfort and convenience to the homeowner.

Inside Hybrid Water Heating