Hood vent size for ERV
canadianexpy
| Posted in Mechanicals on
Hi
I have question regarding hood vent sizing for my exhaust and intake for my ERV.
My HVAC plans call for 8″ intake and exhaust for my ERV, but the only vent hoods I could find for 8″ duct work have a 4.25″ x 8.5″ opening. My concern is that the are of a 8″ cirlce is larger than the rectangular opening of the vent hoods
Will this cause issues with the performance of the ERV and the calculations done for my HVAC plans.
Thanks Dave.
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Replies
The pressure drop caused by the vent hood would have been accounted for in the HRV design. It's usually around 60 feet of effective length.
Thanks , I was hoping that there was some account for the hood vents,( I knew my designer was a smart guy including this in his calculations) just wasn't sure if my hood openings seemed smaller, it was a tough item to get.
Thanks again
It's a good question, and those hood vent restrictions do have a big effect! The same effect as 60' of straight metal duct.
Unless the ERV is for an smaller office building, you should not need an 8" vent hood. Two of those are pretty big holes to punch through a wall for not much benefit.
A decent 6" vent should be around 20 sq in free area, you can push at least 130cfm through it with minimal losses, 200cfm if your blowers have some extra pressure budget.