Tony Hwang <
drag...@shaw.ca> wrote in news:TR2cs.594$6h7...@newsfe08.iad:
>
I partially agree. I think I have to take back my implied designed to fail
statement as I think the real problem is they have not perfected the
Manufacturing process. Reference the piece below on Rifled Copper. Now my
question to you experts is: Are the cheap window AC units with less seer
rating using rifled copper ? I suspect not. Most have good reliability.
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For about 20 years, the AC industry has been under pressure from both
environmental and conservation groups. To improve efficiency, the industry
started rifling the interior of the copper tubes that go into the cooling
coil. They create spiral grooves, and that causes turbulence in the flow of
Freon as it changes from a liquid to a gas. The result is a remarkable
increase in cooling efficiency.
Unfortunately, rifling introduces stress concentrations that become points
where cracks can form and propagate. The entire industry has found a
dramatic increase in the failure rate of their coils. Some customers
experience repeat failures, while others have zero problems.
In 1995, I installed in my home and my duplex, a total of three systems
(including the coils). Since then, neither system has developed a Freon
leak. On the other hand, I have customers with repeat failures. Charles had
4 coil failures in twelve years. Mary had 4 coil failures in eight years.
Eleanor had 5 coil failures in 15 years. I personally have documented the
evidence.