When a First Co. Aquatherm® "Combo Heater" (air handler) is connected to an adequately sized natural gas, LP, or oil fired water heater, the water heater becomes a dual function appliance that can provide comfortable, efficient space heating as well as hot water for domestic use.
First installed in California in 1974, there are now over a million Combo systems in operation from Canada to Florida and in both single and multi-family applications.
ok that's interesting and no what I expected
I think to have the water the right temp for domestic hot water, the temp is too low for efficient heat exchange in the furnace..but who knows