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Shared HRV

PNCPhil
PNCPhil Member Posts: 1
in Indoor-Air Quality

On one of our current builds the house has a self contained basement suite. The house is being built to a high performance standard, well insulated, extremely airtight. We have a plan to use the main HRV for the main portion of the house and have a supply air and exhaust air going into the suite. Each of which is 6" diameter galv duct. At the fire separation between the suite and the main house there would be a fire damper to isolate the duct work in the suite in case of a fire.

The building inspector has never seen this application and is asking for the whole system to be engineered, including duct smoke detectors, relays to shut off the air handler and HRV. My question is, has anyone done this application and what steps were taken to prevent the spread of smoke and fire? I don't see an issue with the exhaust, but the fresh air supply goes from the hrv to the return side of the air handler and branches off to run fresh air to the suite. So, if a fire was present in the main house, the FA supply could spread smoke into the suite. This could be resolved with the system described above by the building inspector.

Comments

  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 18,857

    This will vary by state and the size of the unit. You going to have to search the fire prevention regulations in your area which the inspector can probably point you to.

  • Kaos
    Kaos Member Posts: 762

    As @EBEBRATT-Ed said, rules are very local. Around me for an ADU with shared ducting, the return needs a smoke sensor interlocked with the blower.

    Might be simpler to skip the HRV connection and go with exhaust only ventilation or a dedicated spot ERV like this just for the ADU:

    https://na.panasonic.ca/indoor-air-quality/ventilation/erv/whispercomfort-60

    You can get a tandem wallcap for these which makes the install a breeze. I've used the older version of this for ADUs before in lieu of bathroom exhaust fan and has worked quite well.

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