Re: Return Air Duct

Tony Hwang wrote:
mcp6453 wrote:
Tony Hwang wrote:
mcp6453 wrote:
The return air duct on my upstairs heat pump (the same one with the
thermostat issue also discussed here) sucks air through the filter
at such a high velocity that the filter is not of much value. (It
also pulls the bathroom door up against it, if I'm not careful.)
The present grill is 20x25x1. I cannot find a much larger one. Is
there any reason that I could not or should not add a second
20x25x1 above it? There is room on the wall, and the AC guy says
that the duct work is not that hard to do.
Hi,
Some filters are air flow restrictive for better filtering. Tried
different kind of filter?

The higher efficiency filters make too much noise because the air
flow is so high.
Hi,
Typically blower runs at medium speed in heating mode and high speed
in cooling mode for obvious reason. Wonder if installer had proper
calculation done for sizing the ducts.

Not on a heat pump - read the original posting Tony.

BTW: any air speed above 400 fpm on the grille will cause enough noise to
be heard. It is likely that, with a 20 x 25 grille face, making enough
noise to be heard is a 5 ton unit trying to draw 2000 cfm .... adding a 2nd
return duct and grille at a 2nd location will reduce the noise [air speed]
at the 20 x 25 grille and be less noticeable. Without respect to the supply
ducting, simply cutting the air speed by adding a 2nd duct will reduce the
noise.

--
Zyp


.

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