DIYbanter - View Single Post - Blower motor died on a 18 year old Furnace: Update.

wrote:
You're right. I called them and said what's the alternative to the new
furnace? They said well, you'll be throwing good money after the bad,
but you can replace the blower motor. We'd have to sell you the wheel
as well as those things usually stick to the shaft so much they can't
be removed, and we'll have to inspect the heat exchanger and if we find
cracks we are obliged by law to shut off the heat (you can re-start at
your own risk), yada, yada, yada... The more he talked the more I was
seeing through the thin veil of wanting to sell me the furnace. I may
still need a furnace, mine is 18 years old and may very well be on its
last leg, but I want to be able to make the decision calmly, not under
pressure of "no-heat in the dead of winter". So, if this fix will see
me through this heating season, it will have paid for itself. BTW,
what are the risks of running the furnace with a damaged heat
exchanger? From what I read, the CO is not that much of an issue since
the heat exchanger is under positive pressure from the blower and the
flue gasses just will not escape into the distribution air. Am I wrong
on this? I understand there is no real good way to check the heat
exchanger, but are there signs of a HUGE problem? Like if I look
inside and see orange flames or something like that. I don't, BTW, I
see nice blue flames that look as they should.

Thanks, guys!
Vladimir

Uh, you are forgetting something about the furnace
construction. The burn areas is just a short
distance from the filter housing which is often
just part of the cold air return duct and is often
very leaky.

Assume that you have a CO problem. The positive
pressure may well push most of the CO into areas
where it is sucked up the flue, but some may go
outside the furnace sheet metal move up 2-3 feet
and get sucked into the air duct.