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Community and Q&A

Humidification with HRV

Mark Helmrich | Posted in Mechanicals on

In winter months running our HRV can be a dry painful experience. In Northern Canada (ok Northern Alberta) when temp’s get below -30C air becomes extremely dry.

As HRV also acts a dehumidifier (from what I understand) this exaggerates the dryness even more.

The house has primary radiant heating only, with HRV’s as the only means of moving air.

I contacted the company who installed the HRV’s and they suggested this…

http://www.generalfilters.com/search/Model-DS15P-Steam-Humidifier_PT701.html

Thoughts? I know a HRV does not move much air. I’d imagine I have to run the system on med speed at least.

Thanks,

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Replies

  1. Anon3 | | #1

    Turn off the HRV or run it less. Stop using bath exhaust, buy one of those indoor dryer vent filter boxes... Have more people in the house.

    ERV is better than HRV, too expensive to replace though.

  2. GBA Editor
    Martin Holladay | | #2

    Mark,
    It makes sense to operate your ventilation system when the effects of ventilation are beneficial. In very cold dry weather, you don't need as much mechanical ventilation (especially if your house is leaky). So turn off your HRV under these conditions (or operate it much less frequently).

    To improve the conditions inside your home, you should seal air leaks in your home's thermal envelope. That will help keep indoor relative humidity levels at a more acceptable level.

    -- Martin Holladay

  3. Mark Helmrich | | #3

    Thanks guys.

    House is spray foam and recent blower test shows very little leakage. This is a very tight house.

    If I don't run the HRV i'm worried that indoor air quality will suffer. The HRV runs ever 15 min on eco low, what is its lowest setting. Its barely running at all.

    It so dry in the house that the HRV control device can't even display the moisture content...instead it just displays "low" as its below 25-30% what is out of range of the devices measuring.

    And ERV would have been nice but to expensive now. The humidifier I'm being recommended http://www.generalfilters.com/search/Model-DS15P-Steam-Humidifier_PT701.html is about $1000...not cheap either.

    But I have to do something in winter months.

    I'm just wondering with the low air velocity of a HRV is it even possible to use a humidifier like the one in the link?

    Is there perhaps room misters that can be added instead of one in the duct work?

  4. GBA Editor
    Martin Holladay | | #4

    Mark,
    If your house has very low levels of air leakage, ordinary human activities like cooking, showering, mopping the floor, and watering your houseplants should keep your indoor air somewhat humid.

    My best guess is that your house has leaks -- even though it is insulated with spray foam. These leaks can occur between the foundation and the mudsill, around doors and windows, between the subfloor and the bottom plates of exterior walls, and through your attic access hatch.

    If your indoor air is so dry that it's driving you crazy, it's highly unlikely that you have no ventilation. Your house is probably ventilated, even when the HRV is off, by air leaks and the stack effect.

    -- Martin Holladay

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