On Dec 22, 8:39*am, "Ray" wrote:
Recently I read somewhere that it's possible to add an auxiliary tank to
supply water heaters.

The purpose is, water comes from underground into a storage tank, where the
temperature of the water is raised by ordinary basement temperatures -- *
especially in furnace rooms.

This water then feeds water into the heating tank at a considerably higher
temperature, thereby saving energy costs.

This is common sense. Is this technology available now?

Is the technology avalaible? Having a rooftop black tank and a mini
water heater is standard affair in Mexico and other countries that
dont have alot of extra cash. I took an old water heater stripped the
insuation and use it to temper incomming water, it goes up by maybe 6f
in a day. But you will need a tray under it to drain when it swets in
summer if your basement gets humid. Maybe a cheap uninsulated Well
tank will work. In summer you will save a bit.