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Posted by Joseph on February 4, 2007, 1:50 am
> Whew got that top post back again. :)
>
> How the heck do you avoid having a system with a TESP of 0.7" or 0.8"
> when a wet coil is 0.3". The high grade media filter is 0.15" or more
> when new. You've got another 0.06" or so in grilles. You're already
> over 0.5" w/o any duct work.
>
> I was at a product meeting the other day and had another contractor
> tell me you have to design the duct to allow for the static the other
> things eat up and still keep the TESP at 0.5" max. Must be that new
> no SP duct. I've been designing around 0.7" with AC and 0.4" w/o.
>
> My complaint to the rep putting on the meeting was we need better data
> from the manufacturer than what the blower will deliver at 0.5" when
> there's no way we can realistic way to keep under 0.7".
The .7/.8 were just averages I pulled from my fleeting memory. Quite a few
times the SPs went over 1.0". I was
theorizing that units running for extended periods at High Static Pressures
would see premature unit failures.
It's been a dozen years since I've done any installations but I have had to
go in after and re-duct to bring the SP
down to .5". When I was installing (mostly Trane units using flex!) I never had
any difficulties keeping the .5" SP
pressure required. In the repairs I have made almost all of them were because
of undersized R@ ducts (hacks) or some
type of electrostatic filter. I don't know if I buy the idea of a wet coil
always being = .3".
Joseph
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