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Community and Q&A

I am giving up in Illinois

user-6056070 | Posted in GBA Pro Help on

For the past 6 months we’ve been trying to find a qualified contractor who can design and install a Mitsubishi hyper heat system for a 3K sqft gut rehab home.

We are trying very hard to break away from the traditional horse cart technology of a furnace and blower.

It’s practically impossible to find someone who works on these new inverter-based systems. First off is the issue with Manual J and Manual S. The city requires this, and I understand that the inverter systems may not fully align with the Manual J/S norm.

1. Can anyone recommend an HVAC designer that can help us with Manual J and S calculation to satisfy city requirements with an inverter based system?
2. Any recommendations for a good contractor in Illinois that works on Mitsubishi hyper heat systems?

Here is the snippet from our city:
R403.7 Equipment sizing and efficiency rating (Mandatory): Heating and cooling equipment shall be sized in accordance with ACCA Manual S based on building loads calculated in accordance with ACCA Manual J or other approved heating and cooling methodologies (R403.7, 2015 IECC). The building loads must be calculated with a winter design temperature of 0 degrees F (Village Code 4-1-8(B)23 and a summer design temperature of 91 degrees F dry bulb. The full Manual J calculations/report with all information required to confirm that the R-values of the building envelope; U-values of windows and areas of windows, walls, ceilings, etc.; volumes of rooms; etc. match the architectural design drawings for the house must be provided. Also, the Manual S report must include the equipment specifications and output which will be compared to the heating and cooling loads from the Manual J report. Heating equipment must be sized to accommodate 100-140% of the heating load. Cooling equipment must be sized to accommodate 100-115% of the cooling load. Equipment cut sheets must be included in the submittals.

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  1. GBA Editor
    Martin Holladay | | #1

    I'm glad to hear that your city requires a Manual J calculation. While a Manual J calculation is required by almost all building codes, many building departments fail to enforce this requirement -- and they should.

    If I were you, I would contact an energy rater certified by RESNET or BPI and ask the rater to perform a Manual J calculation for you. The RESNET website and the BPI website include online tools that allow you to find an energy rater in your geographical area.

    If you are having trouble finding a contractor who installs Mistubishi minisplits, you might want to contact Mitsubishi and ask about contractors who serve your area.

  2. Dana1 | | #2

    Like some of their competitors, Mitsubishi has a "contractor finder" page on their website, as well as a rating system based on how much training those contractors have undergone with the distributor.

    Meeting the letter of code on the cooling requirement with a maximum of 15% oversizing seems unrealistic, since the sizing of equipment often had larger steps than that, but the 1.4x oversizing for heating should be do-able. Since cooling systems aren't generally mandatory for a certificate of occupancy you can probably just size it optimally for heating and be done with it.

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