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Community and Q&A

Ventilation with minisplits

BGreene | Posted in Mechanicals on

In a tightly sealed house using only mini-splits, what is the recommended way to ventilate for fresh air? As I understand it from reading various articles, the best way to ventilate is a supply or balanced system. With mini-splits, are people installing ducts just for ventilation or just exhaust only systems?

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  1. user-1035959 | | #1

    How big is the house? Is it an open floor plan? If there's no ductwork now an exhaust only system like a panasonic whisper quiet would probably work best for the least cost.

  2. GBA Editor
    Martin Holladay | | #2

    Here is an article to get you started: Designing a Good Ventilation System.

    As houses get tighter, an increasing number of experts are turning away from exhaust-only ventilation systems. To learn more, see How Much Fresh Air Does Your Home Need? However, as long as your house doesn't have any atmospherically vented combustion appliances, exhaust-only ventilation systems can work. In a very tight house, you may want to consider installing passive air inlets if you go this route.

    If you install a balanced ventilation system, you will (of course) need to install dedicated ventilation ductwork.

  3. BGreene | | #3

    Thank you for the response. We're in the conceptual phases of design, but the house will be around 6500sf (5 beds & and guest/office space) and generally open floor plan (in a mixed/humid climate.)

    I appreciate the advantages of the mini-splits (low cap costs, low op costs), but have been apprehensive about them using them as the only source of heating/cooling. I suppose in larger homes they may work well for bedrooms, laundry, office, etc, but ventilation would need to be duct-ed into (most of) the rooms.

    It appears the guys at Building Science are recommending hydronic heating & cooling with a separate ventilation system to provide fresh air and control humidity. But, its not clear to me if they are recommending this for residential, or just commercial. I've heard hydronic heating can be difficult to control in a tight-home, and contractors seem skeptical about hydronic cooling. Since a ventilation system is required, the general response has been "you might as well just install a traditional HVAC system."

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