"Tokai" wrote in message

I can either replace a heat exchanger for about $400 (part under
warranty, labor based upon actual time), or buy a new furnace installed
for a net price of $2,600.

Using just logic alone, I'd replace the heat exchanger, since it appears
you're getting it under warranty. It will take a long time to recover the
cost of a new furnace, even if you DO realize the savings you calculated.
The last few % of effeciency is questionable in my mind - you already have
an efficient furnace. Heat exchangers should last a lot longer than that -
have someone you trust (if you can find such a furnace guy) evaluate this
situation. Why did the first one get plugged up.

Other reason I would not send more moeny to the same furnace company, or use
the same contralctor that cleaned your present furnace, is: many furnace
heat exchangers last a lot longer than 10 years. You got some junk there
and are thinking of buying more of the same.

It's a trap to build a crappy furnace, than offer you discounts and rebates
to sell you more crap. I dispise that.

Rich