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Community and Q&A

Air exchanger ducting strategy

climb_on | Posted in Mechanicals on

We are in Minnesota (Zone 6a). The home is an “L” shaped, 2200 sq/ft single level, slab on grade. Our floor plan is attached. We will be using a mini split for primary heating and cooling and electric baseboard to satisfy the code.

I can’t even get an HVAC contractor (even a Mitsubishi diamond contractor in the metro area) to return my call. So at this point it’s seems pretty unlikely I will find someone to calculate the load or do a manual J or give me a bid on a mini-split and HRV/ERV system. I’m guessing their is a bigger margin for forced air systems, so they have no time for me. I’ll keep trying, but in the mean I need to gather as much info as I can and start to learn the software to do my own calculations. The exchanger will likely be installed in the laundry room.

3 strategies for running the HRV/ERV that seem plausible to me are:

1. Run the ductwork in the attic (doesn’t seem like a good idea).
2. Drop the ceiling (false ceiling) in the hallways to create a chase and run the HRV/ERV ductwork into the bedrooms and living room that way. I wouldn’t get to the far side of the living room this way though. It would give me a good place to to put the mini split lines too.
3. Go with a Lunos E2 system.

Any suggestions how you would tackle this?

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  1. climb_on | | #1

    Here's the floor plan.

  2. GBA Editor
    Martin Holladay | | #2

    I don't know how far along you are -- is the house already framed? -- but in general, figuring out where to locate the ducts is part of the designer's responsibility. This is one of the things that needs to be considered when you plan ceiling heights and figure out whether or not you want to have a basement -- not at the end of the design stage.

    Second: Here is a link to an article that may give you some ideas on your Manual J problems: Who Can Perform My Load Calculations?

  3. climb_on | | #3

    Thanks Martin. No it's not framed - we haven't started yet. We're just finishing up the plans. A basement is not an option on this site and we have 9' ceiling throughout, which allows me plenty of headspace in most areas to drop it for air exchange ductwork. I told the designer we were not using a forced air heat and cooling system, so perhaps he never gave ductwork another thought. The couple HVAC contractors I actually talked to so far either said they have no idea how to design an air exchange system without a forced air furnace and it's associated ductwork. Perhaps I just haven't found the right contractor yet, or perhaps i've painted myself into a corner with this whole idea of a mini-split system as my primary source for heating and's all a learning experience.

  4. GBA Editor
    Martin Holladay | | #4

    Here are links to articles about designing a ventilation system:

    Designing a Good Ventilation System

    Ducting HRVs and ERVs

    Installing a Heat-Recovery Ventilator

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