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Let me say up front that I'm old and getting crabby and I really don't care what
other people think. I do, however, care how they are treated. And I find the "hood-wink" job done
on consumers who really don't have a problem a travesty.
I know you'll find web sites all over the internet cautioning home owners on the
dangers of carbon monoxide due to a cracked heat exchanger, and the need for immediate action.
You'll also find a lot of web sites peddling vitamins that will grow your hair, reduce your weight
and give your car extra gas mileage. They have a lot in common.
We put this web site together to try and correct one of the biggest fallacies
concerning gas-fired, warm-air furnaces. That fallacy is that a small hole or crack in the heat
exchanger poses such an eminent threat to safety that the service contractor or gas utility will
red-tag and shut down the unit - regardless of circumstances.
The fact that the furnace gets tagged is not the issue. The fact that they will
shut it down in the middle of winter and leave families without heat is the issue. In many cases
they force a replacement system on a home owner who is not prepared (and in many cases, cannot
afford) to purchase a new furnace or system.
There is no question that a crack or hole in a heat exchanger means that the heat
exchanger or furnace should be replaced. The question is "exactly how urgent is it?"
The stated concern is that the crack or hole will allow carbon monoxide to enter
the living space of your home. This is totally wrong. For equipment made in the last twenty years,
it is physically impossible for gasses on the inside of a heat exchanger to pass through a small
hole or crack and get into the blower's indoor air stream. Even if the crack widened to twice its
size during operation, it still won't happen.
Don't forget that the same gas (natural or LP) that powers your furnace is also
used in your gas stove and oven. So, it is not the gas by itself that causes problems.
A small hole or two or three inch long crack does NOT present an immediate, real,
hazard. It normally will not affect operation (depending on location) and will probably take a
service technician a few minutes to even locate. That crack or hole may have been in the unit for
years without causing any trouble.
For some reason, the industry, in general, has subscribed to the theory that a
small crack or hole is a life threatening circumstance requiring immediate action. Very few
technicians actually check the furnace to see if it even emits elevated levels of carbon monoxide.
In fact, many of them don't even know what the acceptable levels are.
So, because many technicians succumb to the boogie-man theory of diagnosis, the
consumer gets the short end of the stick. The technician sees a crack or an actual hole in a heat
exchanger and fear sets in. They immediately start repeating what they heard other guys say about
the problem of carbon monoxide and how dangerous it is going to be for the occupants.
Somebody told them that if the heat exchanger is cracked, that it will now
automatically produce carbon monoxide. That information is incorrect. It has been wrong since the
days of sectionalized heat exchangers, modern duct work and automatic blowers.
The carbon monoxide fears due to cracks are a hold over from the 50's and 60's when
gravity furnaces and in-shot power burners were in use. In that era the duct work connected to a
furnace might be two or three times larger than necessary. (Remember the big round ducts on gravity
warm air furnaces.)
But, this is such a far-reaching and prevalent issue that it is even written into
national building codes, local ordinances and utility provider operating procedures. In other words
... it has become "law".
Unfortunately, with the emphasis on heat exchangers, the other areas that affect
carbon monoxide and safety are being ignored.
There's no question that a cracked heat exchanger should be replaced. The issue
becomes, exactly how urgent is it? Is it so dangerous that a family should be forced out in the
cold, to spend money they may not have, and do it without being able to get competitive bids?
Best regards and stay safe,
Gus
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