Return air – jump ducts vs transfer duct with baffles
Just curious if anyone had first-hand experience comparing jumper ducts with a product like the Tamarack RAP (https://www.tamtech.com/product/return-air-pathways-new-construction/).
We’re building a house where we’ll have centralized returns. Current thinking is jumper ducts to provide a return air pathway for the bedrooms. But noise mitigation (keeping noise from living areas out) is a focus. Is one likely to be better than the other?
It is what it is so no point in telling me to change it – the supply and return ducts will already be in the attic for the second floor, if that’s a factor/concern with the jump ducts being up there.
Thanks!
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I haven't compared, but I did install several Tamarack RAPs a few weeks ago. They seem to do what they are supposed to do. I can't quantify anything but when bedroom doors are closed and I stick a piece of paper up to one of the RAP grills, it gets sucked on pretty tightly, so return air is definitely flowing.
I will add that although the cardboard honeycomb between the grills does an OK job of filter light, it does not do much to filter sound. So keep that in mind when you select exactly where to install them.
Thanks for the comment on the sound filtering. That's very helpful info, though I was hoping to hear this was a magic product we should use to simplify things :)
I can't compare the two, but I have jumper ducts. They work - I can definitely feel ALOT of airflow coming out of them on the hall side, and they hold paper on the bedroom side to the point where I was wondering if they should have been larger, but there is no hissing or whooshing sound at the intake or output, so I suppose they are ok. Air is definitely flowing.
There is absolutely no light exchange between the two as each grill is in the ceiling, and the attached flex duct in the attic is in an upside down U configuration, and unfortunately in an unconditioned attic. The duct transfers already conditioned air, so at least it is not the initial delivery of conditioned air.
There is very little if any sound transfer through the transfer duct. I have a Main Bedroom suite adjacent to the living room, with a short +/-5 hall between. The transfer duct goes from the hall to main bedroom suite. The walls between the Main bedroom suite and the hall/living room are dense pack cellulose. The main sound transfer seems to be at the door undercut.
The transfer duct terminations at the ceiling grills are very unobtrusive, so aesthetically is it great, and it was easy and inexpensive to install.
Thank you - I appreciate you sharing your real-world experience.
Sounds like jumper ducts may be better for sound transfer, which is what I suspected/expected. Maybe I'll do that for the master bedroom, but use the RAP for the other bedrooms.
For sound and energy, what works the best is a high low return in a wall. This is just two duct elbow boots connected by a length of flex. This saves you putting two more holes to the attic and it is pretty easy to install for a new build.
It does take up space, you generally want to put it into a 2x6 wall as you can't fit a big enough flex into a 2x4 wall. The flex should have a lazy S bend and the cavity stuffed with as much insulation as possible. Make sure to seal the boots at each end to the drywall.
For better sound attenuation you can get in-line duct silencer which are very effective. You can use one between the two boots. They do take up a bit more space though.
Unfortunately our layout doesn't allow for high-low returns. There aren't shared walls to open space/hallway into which we could put them.
We're stuck with either 1) dedicated returns, 2) transfer ducts above the door 3) jumper duct near the door.