" wrote:

Model Energy Factor Cost to Operate* Annual Savings¹ Annual Savings²
250SX/SXO 0.85 $250 $110 $151
125B/BS 0.69 $308 $52 $93
125HX 0.80 $266 $95 $135
125FX 0.78 $273 $88 $129
40-gallon tank 0.59 $361
75-gallon tank 0.53 $410

Note the stated savings. In the winter the extra gas used helps heat
your home If the heating season lasts 6 months then divide the savings
by ONE HALF.

Now the largest savings bosch lists is $153 divide by 2 it saves about
76 bucks a year. Thats nice BUT the install costs several times the
cost of a standard tank.

The heat from the extra gas used mostly goes up the chimney, not into
your home since it's mostly stack losses, not losses through the
exterior of the heater. What heat does get out into your home may assist
in heating it in the winter, but it also hurts when air conditioning in
the summer.

Pete C.