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Source for Forced-Air Heating Wall Vents

severaltypesofnerd | Posted in Green Products and Materials on

What’s a good source for forced air wall/ceiling vents that can be 100% sealed off by the building residents (for example if a room is not in use)? The typical wall vent has lovers that only kinds sorta block flow and make a lot of noise doing it.

This would be for forced air systems, for example those with 4″ metal ducting, or 4″ flexible ducts.

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  1. GBA Editor
    Martin Holladay | | #1

    First of all, forced air heating systems need a minimum amount of air flow to prevent damage to your furnace's heat exchanger. That's one reason why zoning a forced-air system is difficult, and why contractors want to see some air flow (even when zones are damped down).

    Second, no manufacturer sells a register like the one you describe. For Passivhaus builders who want an outdoor air duct to bring combustion air to a room with a wood stove, I've been known to advise the installation of a 4-inch ball valve or a 6-inch ball valve on a round duct. Ball valves are plumbing fittings. They are airtight. They are also big, expensive, and ugly. But they work.

  2. Expert Member
    ARMANDO COBO | | #2

    The short ansnwer... NEVER! A room with a supply vent in it, shold not be closed, as more likely, it was designed to be there with a purpose in mind. Blocking or closing vents messes up with the design flow of the duct system and can create greater static pressure in ducts that can restrict flow to other rooms as intended.
    The V in HVAC systems is for ventilation. All rooms with outside walls should have a supply vent. Any room with a Manual J design load of ≥5 cfm needs a supply vent to avoid building envelope problems.

  3. Jon_R | | #3

    I found clear tape to be reasonably effective in sealing a register.

  4. severaltypesofnerd | | #4

    @Armando, I don't buy the "never" comment. You're assuming whoever designed the system had not only purpose but skill. I don't buy it in terms of reality. How many houses have an unheated (but insulated) garage next to a heated room?

    This all begs the question: if I want to (seasonally, or depending on number of occupants) seal off a duct or vent, what's the best way to do it?

    If it helps, the room in mind is in a non-freezing climate, with no AC, forced air gas heating.

  5. severaltypesofnerd | | #5

    In this case it's an axillary room and other vents are 100% open, so a complete shutdown of the room's vent would cause zero issues upstream.

    Are there any manual (e.g. slide a panel in) air shutoff valves?

    Do any of the motorized zone dampers provide 100% complete shutoff? I could put a zone damper upstream from the conventional vent, with a wall switch for shutting off the zone.

    This is a room that, as far as I can tell, has been heated for no particular purpose for about 35 years. Adding a zone damper would not be easy though, as the pipes were helpfully wrapped in asbestos by the homeowner, in a well meaning effort to save energy.

  6. Rob Myers | | #6

    I have suggested this in a previous thread - one option is to use dust collection system blast gates. They are readily available up to 6" in diameter (there may be larger ones available) , they are relatively inexpensive, they seal very well and they are easily automated. Here is a link to a Canadian supplier that I use (almost any woodworking shop supplier will stock these):

  7. Jon_R | | #7

    Partially blocking some ducts/registers is a requirement to getting a well balanced system (ie, every room is the same pressure and temperature).

  8. severaltypesofnerd | | #8

    Airtec 81901 (Model: MV360S)
    "Made from high impact polymers and featuring a virtually airtight damper for winter shut off and/or volume control"

  9. Mizmowr | | #9

    @ Bryce or others: Found this thread (and site) under a Google search. My question is very similar to Bryce's. I am renovating my garage by among other things insulating it. At the same time, my old HVAC gave out and I got a new one installed. I asked the installers to run a duct and ceiling register over to the roof of the garage, and they did (easy, no increase in their estimate). However, I noticed that: a) the register doesn't really seal and makes a lot of noise and blows air into a space I really only wanted heated or cooled a fraction of the time; and b) it's in the ceiling, darnit, which is 10' off the floor and not really accessible anyway. Long story short, if it seems that there isn't a way that I can only run air to the garage *when I really want/ need it*, I'm thinking about calling the HVAC guys back in to simply un-install the whole garage run. Ideas?

    1. charlie_sullivan | | #10

      It's unsafe to have the main HVAC system connected to the garage, and you will then be mixing the garage air, which is polluted by various things, into the house. Get that disconnected and get a different solution for occasional temporary garage heating.

      1. Mizmowr | | #15

        Made a whole new post to reply to your helpful reply and others; please see the main thread.

    2. JC72 | | #11

      Assuming they just ran a supply duct you could install a motorized damper in the duct.

      If they also installed a return in your garage, which I hope they didn't, then you should rip it all out and install a small minisplit.

      1. charlie_sullivan | | #12

        With no return in the garage, you are pressurizing the garage and depressurizing the house, and you are counting on 100% air sealing between the house and the garage to resist that pressure difference, while expecting the air flow being from the garage to the great outdoors, and the outdoors to the house, so you are counting on the air sealing elsewhere being poor enough for that to happen. I wouldn't count on that working, and even if it did work, it would be an inefficient way to heat the garage.

      2. Mizmowr | | #16

        Made a whole new post to reply to your helpful reply and others; please see the main thread.

  10. Expert Member
    NICK KEENAN | | #13

    You can get magnetic covers that close the vent off. But you also have to make sure that the vent is well-attached to the duct, and that the duct doesn't leak.

    1. Mizmowr | | #17

      Made a whole new post to reply to your helpful reply and others; please see the main thread.

  11. Mizmowr | | #14

    @ Charlie, John, DCContrarian: Looks like it was overall a bad idea to have a duct run to the garage. Nope, they didn't install a return, so that part of the safety issue is at least minimized. But for occasional climate control, looks like I need to get an occasional solution.

    Any ideas?

    Here's a few things I found:
    * (not sure if this is just a/c or heat as well)

    One last thing. I also have a detached shop w/ no air currently. Eventually I'd like to get around to installing something out there (as well as a whole-shop dust filter). Point being, experience gained for the garage should work for the shop and vice versa.


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