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Community and Q&A

What direction should I go with my new/used home?

Todd Stout | Posted in GBA Pro Help on

I purchased a 23 year old home to accommodate my growing family. It was constructed with double wall construction, wood foundation, Envirovent system etc. We live on Nantucket Island.
I am planning to install a mini split system and have questions on further improvements, possibly solar, that are upcoming.
My first inclination was to update systems based on the recommendations of local hvac contractors until I realized that my new home is unique and that I might need specialized consultation from someone more familiar with this “type” of home.
Any advice or suggestions are welcomed.

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  1. GBA Editor
    Martin Holladay | | #1

    GBA is a useful resource, and GBA readers are ready and able to provide advice.

    I suggest that you start by posting a specific question.

  2. Expert Member
    Dana Dorsett | | #2

    Marc Rosenbaum (over on MV) may be willing to consult with you on this, and come up with reasonably accurate heating/cooling load numbers along with equipment recommendations,. He has a lot of experience with high performance houses:

    I've yet to see a proposal from any of the HVAC contractors on the Cape or islands that wasn't at least 2x oversized, even for conventional construction, let alone a double studwall house. Your instinct for seeking better informed advice on this is right! The way to deal with it is to have somebody other than the contractor specify the equipment, then put it out to competitive bid.

    A bit over a year ago some friends on MV were quoted ~$40K for a ridiculously oversized ducted heat pump system. I had them get an agressive Manual-J from an engineering outfit, after which they negotiated a more appropriately sized multi-split system from a contractor on the Cape for about $15K, before MassSave and rebates were applied. The local island contractors were still insisting it wasn't nearly enough and refused to even bid it, yet they had no problem with capacity during February's record breaking cold snap.

  3. Todd Stout | | #3

    One initial concern is that the envirovent/Thermastor HPVAC-80-120 has been leaking. The system currently draws air from several locations and is ducted via pvc piping to the unit. Is there anything that would readily replace this unit using the same setup without revamping the whole house?

  4. GBA Editor
    Martin Holladay | | #4

    I visited the Therma-Stor web site and entered "Envirovent" into their search box. Results = zero, so I'm assuming that Therma-Stor no longer makes this product.

    One online document describes an integrated mechanical system this way: "The house also incorporates an IMS [integrated mechanical system] that combines the functions of auxiliary space heating, controlled ventilation, heat recovery, water heating, and auxiliary cooling in one unit. The unit is an Envirovent ® Model HPVAC-120 manufactured by the Therma-Stor Products group of DEC."

    Is that what you have?

  5. Todd Stout | | #5

    Yes. I spoke to the tech and it is discontinued. They are now focused on dehumidification product lines and had no suggestions.

  6. GBA Editor
    Martin Holladay | | #6

    So you have an obsolete appliance -- described in one document as an integrated mechanical system that sounds complex -- that is "leaking."

    Is it leaking air? Leaking water? Leaking lubricant?

    Is it fixable?

    Do you want to replace it?

    If you want to replace it, does that mean you need a new space heating appliance, water heater, air conditioner, and mechanical ventilation system?

  7. Steve Knapp CZ 3A Georgia | | #7

    Todd. I would contact Therma-Stor technical support again. If the tech is not helpful, I would ask to speak to a department manager. Even though this product is discontinued, the company should be willing to help you either fix it or transition to a newer device.

    As someone who owns a Therma-Stor product, I am very disappointed in how the support staff responded to your request for assistance. I'll certainly keep it in mind as I begin to evaluate ventilation systems for my next build.

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