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Bookmark this page: Tankless water heaters
What
types of tankless water heaters use a Solar System Back-Up
Aquastar tankless heaters can be used with solar- or
woodstove-preheated water. As we mentioned, the standard tankless
units sense the outgoing water temperature and adjust the flame
accordingly to maintain a steady output temperature. If the incoming
water has been preheated, the gas will be modulated down to
compensate. The standard Aquastar or Tagaki units can only modulate
heat input down to about 20,000 Btu. The optional Aquastar "S" units
can modulate all the way down to zero Btu, and are highly
recommended if there's any possibility of preheated water in the
future. Standard Tagaki units are not recommended for solar backup,
although a special unit for preheated water is supposed to be
available in the near future. If the incoming water is already
preheated to your selected output temperature, then the tankless
heater will only come on briefly. If your preheated water is at
90°F, and you've got a 120°F output set, then the water heater will
come on just enough to give 120°F output. We think that's pretty
slick, and it gracefully slides us into the next good choice, solar
water heaters.
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