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M Q

wrote:

Speedy Jim wrote:

wrote:

The unit in question is Goodman GMV9509050XBA gas furnace (95% eff.,
90,000 BTU.)
It says in the Installation Instructions (page 7, Location Requirements
& Considerations) that the following must be observed:

"The temperature of the return air entering the furnace is between 55F
and 100F when the furnace is heating."

Yep, they spec that so that condensation is unlikely
to occur in the main (pri) heat exchanger, which could
cause early failure.

It can become a warranty issue (if you care).

Jim

it becoming a warranty issue - how can they _prove_ I ever allowed
the temp to drop below 55F?

They probably can't prove it. The spec just says the range over which
it was designed to work correctly. It might also be that it is not
designed to drain condensate from the primary. It may also depend
upon the dew point of the combustion intake air.
Ask the manufacturer what will happen.