Rob

History is history. Can't take back a decision made 4 years ago.

Now its 80% to anything else.

Information not previously available, and you WERE lamenting the
inability to buy a 60 percent furnace, thus that is what my math was
about. Anyway, assuming that the prices on ebay transfer to the real
world, you are looking at a 100 bucks maybe from an 80 percent to 93
percent. Maybe 8 year payback.

I bought an 86 percent boiler, because we have no gas in the street, and
propane never worked out no matter the efficiency it was always more
expensive. THat decision was made almost 3 years ago, and had I known
the oil prices in the intervening time, I would have bought the 3000
dollar condensing oil boiler Monitor makes, since it would have a
similar payback now, but at the time, with oil at 1.50 a gallon, it
would have taken forever.




All gas furnaces will rust here. The rust is on the OUTSIDE of the
heat exchanger and it is due to our environmental conditions here, not
due to the condensation of the exhaust gas. www.hvacopcost.com, we are
in Zone 5, hot and humid.



Condensing furnaces IIRC, have stainless steel heat exchangers, the
acidic condensate is worse than rain. No rust





In your climate a superinsulated house would be a better return, you
should never need heat. My moderately well insulated house does not
drop below 68 on a 32 degree night. could save the cost of the furnace
and the gas



We are agreed that R40+ in walls and ceiling has a better payback.
Still higher payback comes with a geothermal heat pump with EER near 30
and COP of about 5.