Canadian Contractor

Noisy HRV bothers homeowner. Comments anyone?

"The contractor says if I don't like the noise, don't use the HRV..."

July 14, 2017
By canadiancontractor

Comment from a homeowner following John Bleasby’s recent articles on Passive Houses…

We have just built a house to passive house standards and have put a balanced ventilation system in. I can not tolerate the sound that the HRV makes. The ducting in the house carries the sound of the motor through the house and also transmits sound from one room to another. There must be a system out there that does not make such a noise? The contractor says if I don’t like the noise don’t use the HRV. BUt as your diagram indicates an HRV is essential to a super insulated home.


Reply from John Bleasby…

Eve: I’d get your mechanical contractor in to have a look. My HRV unit is suspended on straps from the joists above, so the unit cannot reverberate against any stud walls. Is yours? Also, your unit should have variable speeds you can program from the master keyboard; maybe yours is set for a high speed, hence the noise? Just some random thoughts. The HRV should not be so noisy as to bother you!


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2 Comments » for Noisy HRV bothers homeowner. Comments anyone?
  1. Hans Eich says:

    This is a topic that too many future homeowners really like to ignore, or are not aware of. I used to sell Zehnder units for Passive Houses, and it’s a requirement for these units to be very quiet and properly installed as to not transmit any mechanical noise into the walls. I’ve had a few customers replace their units with ours, because they ended up turning the units off due to the noise. In an airtight house, that’s really not a good idea.

    My advice? Pick a quiet unit to begin with, mechanically isolate it from the walls it is mounted on (i.e. hang it on extra studs that are not coupled to the drywall, or special rubber decouplers, hanging a unit by a chain can still transfer noise into the ceiling, unless you have springs in there, even then it may still transfer noise through the ducting etc.).

    Also use absorbers in your supply AND return lines, the noise can travel upstream through the ducting. Also pay attention about room to room noise transmission. In a home run system, where all the runs go back to a sound absorbers attached to the unit, it is much harder for any noise to travel between rooms.

    Lastly, sizing the unit too small can also be an issue. If you are running your unit at the max to reach the desired ventilation amount, the fan blades can be really noisy. If you oversize the unit and run it at a lower rate, they can be very quite. Careful though, not every unit lets you set the speed in small enough increments to properly balance the ventilation of the house.

    So it really pays to pay attention to the fine details. I know some of the whole house systems can get pricey, but what is much more expensive is to buy an improper system first, only to realise later that you should have gotten the proper one in the first place.

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