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Posted by Bob_Loblaw on September 15, 2006, 4:43 pm
>
> I'm curious on opinions from pro's of the water test for residential
> heat exchangers advocated by Ellis Prach of
> http://www.heatexchangerexperts.com/ In this test, the tech pulls the
> blower, douses the exchanger with a water solution from a large
> sprayer, and then looks inside the combustion area for water
> penetration. If there's water getting in, they reason, you have a
> breached heat exchanger that they recommend replacing it.
New exchangers from the factory aren't water tight.
It has become increasingly difficult to ascertain whether or not a heat
exchanger has been compromised due to rust or cracks.
Newer exchangers are multi-pass, which makes visual inspections very
limited. There can be other tell-tale signs of a faulty exchanger, such as
popped rings on top of the blower housing, but again, very dificult to see
unless you have a boroscope.
A tripped limit or burner spill switch may also indicate a crack,hole, or
separation.
Flame distortion with the blower on, flame roll-out, continuous pilot
outages caused by air from the fan blowing through a crack. (Always a good
idea to operate the fan with the burners off and watch the pilot for
distortion. I got fooled once as a rookie by a cracked heat exchanger. I
replaced the t/couple on an older furnace thinking it was just old and
tired. It blew out after I left and another tech picked up on it with the
fan-on test.)
The best advice I can give for homeowners is to have your furnace cleaned
once a year, and have a CO detector on every level where people sleep.
Replace it before it's old enough to vote.
--
Respectfully, Bob
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