Depending on the complexity of the system, commercial solar air heaters range from under $1,000 for single room heating to $6,000 for large-space or multi-room applications [source: Darling, altE]. But keep in mind that these are supplemental heat sources; you'll still need your conventional heating system. Solar systems designed to provide central heating aim to replace 40 to 80 percent of conventional heating. They're most cost effective when providing 50 percent of the home's heat [source: NC Solar Center, U.S. Department of Energy]. A simple room heating unit, of course, won't cut your heating costs by that percentage. It will, however, reduce the amount of conventional heat you need to keep your home comfortable.
Installation is an extra expense. Simple unit installation is within the capacity of an experienced DIY-er, but solar air collectors measure around 4 feet (1.2 meters) wide by 7 feet (2.1 meters) high. And they're heavy, so you'll need a helper or two to mount one on a roof. You may need a building permit, and you'll definitely need to make sure that adding the collector to the roof won't exceed its load limit. Larger or more complex systems require ductwork and electrical wiring, but commercial manufacturers are making strides to simplify installations with integrated fans and thermostats that you can plug into existing outlets in your home. If you choose to hire a contractor, look for one with experience in solar installation technology.
Each home is different and climate conditions range widely from place to place, so how much money a solar air heater shaves off your heating bill depends on the condition of your house and where you live. If your house is poorly sealed and insulated, installing a solar heat unit won't save very much energy; solar heated air leaks out just as quickly as conventionally heated air does. Solar air heaters do their best work in areas with long, cold, sunny winters. In warmer regions with short winters, designing the system to do double-duty for household water heating during the summer increases cost effectiveness and accelerates ROI. This is more complicated than adding solar room heating. It requires the addition of an air-to-water heat exchanger to the system. Some designs also require plumbing. Like the solar air heater, this is supplemental energy. It won't replace electricity or natural gas for water heating in most climates, but you can make it work to reduce the cost of this function.
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