Posted by AL on July 19, 2001 at 10:37:00:
In comparing the cost of an indirect vs. a stand alone (gas) water heater, I have the following figures.
Assumptions are based on going from a 1 zone (no controller) house to a two zone with the indirect. Installation costs for the water heaters are assumed similar.
It is assumed that both will receive annual maintenance by the homeowner.
Indirect
40 gal indirect - $800
Zone controller - $100
Zone Pump - $75
Miscellaneous pipe, valves and fittings - $75
Total - $1050
Stand Alone water Heater
40 gal - $250
Misc pipe, valves and fittings - $50
Total - $ 300
Difference - $750
For a stand alone water heater the cost of gas for a year is approx $200.
Let's assume that the indirect uses half the amount of gas - $100, thereby saving $100 year.
At 7%interest on your money, the indirect would take 11 years to pay back.
I realize the indirect will provide better heat recovery. Perhaps a 30 gal indirect is more comparable to the 40 gal stand alone. But this seems like quite a long payback, and has me leaning toward going with the stand alone, even thought the indirect is a more slick set-up. Also what about the fact that you run the boiler in the summer for short bursts to heat the indirect. Is this more harmful than helpful?
Appreciate the great feedback here on the Wall.