Vent registers
We are having new hardwood floors installed and would like to have recessed registers put in place. My research indicates that the recessed wood registers don’t allow sufficient airflow. As we would like to make sure our furnace is in fact operating at its best efficiency, we want to install floor registers that allow the maximum airflow possible. You had an article on this subject by Allison A. Bailes III, PhD entitled “Designing Duct System Vents for good Air Flow”. The article had a picture of a recessed vent as an example, but I can’t seem to find it. Attached is a copy of the picture. Any idea where I can find it, or something that would give me the airflow that I’m looking for along with the asthetics of a recessed register?
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Replies
Mary,
A grille does not include an integral damper. Grilles are usually used on return air ducts.
A register includes an integral damper. Registers are usually used on supply air ducts.
It's possible to use a grille on a supply air duct if you want -- as long as you accept the fact that you can't shut the grille.
Several manufacturers make flush-mount metal grilles, but I don't think anyone makes flush-mount metal registers.
Here are some links:
Metal flush-mount floor grilles
Metal flush-mount grilles
It should be possible to add a damper in the supply duct if you want to use a basic vent and not a register with an integrated damper.
Bill
Hi Mary -
Believe it or not, supply registers are the last step in effectively and efficiently delivering and distributing the conditioned air to the space. The Air Conditioning Contractors of America (ACCA) even have a standard for this last step called Manual T (https://www.acca.org/store#/storefront).
I don't have a copy of that standard but it is entitled ACCA’s Manual T: Air Distribution Basics for Residential and Small Commercial Buildings.
Best thing I can suggest is that you check with your HVAC contractor OR whoever is selling you the register or grille and ask them about Manual T compliance.
Peter
You can make up for the inefficiency of wood grilles by making them larger. For example, provide a 6x16 wood grille instead of 4x12 metal. Some grille and register manufacturers give "free area" numbers for their products, which you can use to compare. I did what Zephyr7 suggested: put dampers in ductwork and skip the control at the grille. Of course it's a little less convenient and you'll need to have a house where you can get to the dampers. Many of the residential registers have dampers made of plastic.
IMO, both supply and return should have dampers - so that the room pressure can be balanced.
Something like this https://www.priceindustries.com/content/uploads/assets/literature/catalogs/catalog-pages/section%20a/lbplbphlbmlbmh-linear-bar-grille-catalog.pdf sounds like what you are looking for. You can purchase with dampers to shut off airflow or without, and it can be purchased with a recessed frame for flush mount. It is a commercial grille though and availability might be tricky. You can find similar grilles from different manufacturers, check at your local hvac distributor, they should be able to tell you what is available locally.