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Community and Q&A

Comfort considerations in placement of ventilation supply registers

user-6356169 | Posted in Mechanicals on

We’re trying to decide where to locate the fresh air supply registers for an ERV-based ventilation system. Duct length and placement is one consideration, but what about comfort considerations? We’ll have cool air blowing from these in the winter, and we’re trying to minimize any discomfort from that. I’m especially curious about the experience of others who have lived in houses with ERVs or HRVs and separate ventilation ductwork.

One idea is to just have the supply vents in the hallways upstairs and downstairs, which would have the advantage of keeping ductwork short, since the trunk lines will run parallel to these hallways. And if a hallway is somewhat cool, who really cares? But my concern here is inadequate supply to rooms with closed doors (only one room downstairs but three upstairs might frequently have closed doors.)

If we do have separate supply vents in these rooms, the question is where to place them. We could put them near the forced air heating supply registers (close to the windows, most likely), even though that would lengthen the ductwork somewhat. This would at least provide some mixing of heated air and the cool air from ventilation supply. But we’d only get this effect when forced air heating was being used.

Or, we could try to keep them closer to the trunk lines along hallway. Cool air would blow into rooms. Is this much of a concern? Anybody had any bad experiences with this, from the comfort perspective? I’ve heard that some folks put their supply vents in closets. Seems less than ideal, but might work if closet doors were left open a crack.

Since I’ve never lived in a house with this kind of ventilation system, I really don’t know what to expect. Maybe there’s really not much of a comfort issue with the amount of cool air blowing (probably ~80 cfm for entire house, and if that’s spread over multiple vents … )

Note: We’re hoping to get a lot of passive solar heating in this house, so there will be plenty of times when windows are closed and ventilation system is running, but the air handler for the heat pump won’t be distributing air throughout the house.

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  1. Expert Member
    Dana Dorsett | | #1

    You're overthinking this. The drafts near U0.50 windows when it's +20F out are colder, higher cfm, and less comfortable than the draft of an HRV register at +20F outdoors, but you'll still feel it if it's blowing directly on bare skin in close proximity. A ceiling register or high wall register located where it won't be literally "in your face" is fine.

  2. Anon3 | | #2

    Exhaust from rooms + bathroom, fresh air to where people do not sit.

  3. GBA Editor
    Martin Holladay | | #3

    I don't think you are overthinking this. It matters.

    1. You definitely want to supply fresh air to the bedrooms rather than the halls. Most people spend 8 hours a day in their bedroom, so they need fresh air. Bedrooms can develop high levels of CO2 as the night progresses, and odors can build up.

    2. Introduce fresh air into your bedroom from a location that won't blow at the head of the bed. If you are willing to put louvered doors on your closet, you can introduce fresh ventilation air in the closet, but other locations also work fine.

    -- Martin Holladay

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