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MHRV Balancing - is this installer correct?

  • 13-01-2011 11:18pm
    #1
    tails_naf
    Registered Users Posts: 861 ✭✭✭


    I self-installed my MHRV, but before we use it, I wanted to ensure the balancing was done by an installer, as I have heard on boards that that is important.

    I called an installer up today, and he went through what they do, etc, and one thing surprised me -

    I asked was balancing matching the intake and outtake flows of the unit so there is no net pressure in the house.
    He said that was not important the important thing, and instead the flow-rates to each room would be set based on size - e.g. 13/l/s from a kitchen, or wet room, etc.

    While I know the system would have to be setup for each room, surely the overall flow in and out of the house would be important also?

    He also said that the regs recommended 2 air-changes an hour.
    My own guess is that surely this is excessive (even if it is regs).
    We have been in the house for 3 months, and are relying on passive ventilation at the moment (HRV is off), so its just 2 open chimneys providing the whole house ventilation - and the house is not stuffy at all.

    My concern with 2 air-changes per hour are the fact it seems wasteful
    1) the HRV unit will have to run at max, or close to it - 150 watts of power, 24/7!
    2) If the air is changed in the house every 2 hours (at a theoretical efficiency of 90%) this means effectively one full air-change per day approx, this means heating up 600m3 of air, which I guess is not that efficient?
    3) The above 90% doesn't account for others losses i.e. ducting in the attic, while insulated, will surely loose a significant amount of heat, as the air in it will be at 20 degrees, and the insulation on the pipes is at best an inch thick, so maybe that 90% could be 80, or 70 in reality...

    Is it possible to simply run the unit at a lower speed, and if the house is not stuffy, then that speed is ok?


Comments

  • #2
    gizmo555
    Closed Accounts Posts: 2,948 ✭✭✭gizmo555


    You're right, 2 ACH is grossly excessive. A typical setting would be more like 0.3.


  • #3
    sinnerboy
    Closed Accounts Posts: 5,433 ✭✭✭sinnerboy


    The system must be balanced

    We await from TGDF
    Installation and Commissioning of Ventilation Systems for DwellingsAchieving Compliance with Part F

    But this may assist


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