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What is unbalanced?

John H. Stehman | Posted in Mechanicals on

I have been reading all the posts on ventilation and I pretty much have figured out what an unbalanced erv system is but I would like someone to offically explain it as to what happens and how would you know when it becomes unbalanced.

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Replies

  1. GBA Editor
    Martin Holladay | | #1

    John,
    To balance an ERV, you need a manometer and/or a flow meter. Balancing methods are described in the installation instructions provided by most ERV manufacturers. These installation instructions are usually available online.

    There are two issues to consider: first of all, it makes sense to balance the supply and exhaust sides of your ERV, so that the exhaust air flow in cfm is equivalent to the supply air flow in cfm.

    It's also a good idea to know whether your house is pressurized or depressurized with respect to the outdoors under a variety of conditions. Exhaust fans (range hood fans, clothes dryers, and some central vacuum cleaners) tend to depressurize your house, and a leaky forced-air distribution system can sometimes pressurize your house. These types of imbalances are sometimes unavoidable, but some of these imbalances indicate problems that can be corrected. A home performance contractor or blower-door contractor should be able to diagnose these types of issues for you.

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