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Pressure drop in roof exhaust vent

peter2022 | Posted in General Questions on

Planning the ERV install in my conditioned attic, there is only room on the gable end for a single vent, for the intake, and I will be having an exhaust vent up through the roof.

The issue I’m having is I don’t see a pressure drop or equivalent length rating for any of the vents as they’re more of a ‘roofing’ product than an HVAC product it seems.  Based on the fan curve for my ERV I’d like to keep the total system static pressure below 0.6

However, this video shows that your typical bath fan vent hoods have significant static pressure, many are 0.4 just by themselves.

The gooseneck style seems like it should be the best, but the one they test does a full 180 turn and looks pretty small for the 4″ pipe fitting.

My exhaust will be a 6″ duct.
I’m now questioning if I should try and use a larger 8″ gooseneck that doesn’t do a full 180, like this:

Or if this magical dryerjack, which only comes in a 4″ size, would actually be better.

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