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Community and Q&A

Frustrated with local HVAC contractors – should I outsource the design?

fresnoboy | Posted in Mechanicals on

Hi everyone. We’re building a pretty large house here in the SF Bay Area, and having a devil of a time trying to find an HVAC contractor who’ll actually design things using calcs and not eyeballing it. When I finally got one to do a manual J, he had to quit the program due to a family member with a terminal illness.

The next guy wouldn’t use the old manual J, and said he’d do a new manual J because he didn’t trust the one for $2500, and then say he’s never had a manual J done that was very different from his estimates of X tons per 500 sq ft… And didn’t have answers on how to deal with a plan for make up air etc… Both had excellent customer service ratings and were Mitsubishi diamond dealers (we’d like to use a VRF system).

So my GC and I are frustrated by this and the framing is going to be done soon, so the HVAC is going to start being a bottleneck.

So to move forward, we’re thinking about outsourcing the design of the system, ducting etc…to someone not local, and then bidding out the actual construction and installation of that design.

Do folks here think this is a good idea, and if so, can you recommend someone who would do a good job on this? It’s a very large house, and we want this done right, but not using overkill that kills efficiency. I already have a query out to the Energy Vanguard guys about this and I think they have a good reputation, but would like to know what others think think about options…

If you know someone local would would be good at this and uses calcs in their normal design, that would be good too.


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  1. GBA Editor
    Martin Holladay | | #1

    1. GBA readers should know that any project where "the framing is almost done" that doesn't yet have a heating and cooling system design is probably in trouble. That's the cart before the horse. It's essential to design your heating and cooling system before you begin any construction, especially if your house will include a furnace or boiler. How else will you know how to size the mechanical room, or how much room to leave for ducts?

    For more information on this topic -- and I know, Mike, that this information doesn't really help you -- see Plan Ahead For Insulation.

    2. To answer your question: Yes, it's possible to hire someone who lives out of state to perform the Manual J and design your system. Here is a link to an article that will guide you: Who Can Perform My Load Calculations?

  2. user-626934 | | #2

    There are also certainly some options in SF Bar Area for contractors who do fabulous work...these are people who run and participate in the annual Dry Climate Forum on Home Performance (people who design, install and actually measure performance on their own work). Here's a starting list...the first 2 do most of their work in the Bay Area...the second 2 might be willing to travel.

  3. GBA Editor
    Martin Holladay | | #3

    Thanks very much for your excellent suggestions.

  4. Expert Member
    Dana Dorsett | | #4

    I thought Title 24 2016 REQUIRED a Manual-J, and limits the oversize factor to something like 15% or something.

    How is it that the hack contractors are still operating on ton per/xxx rule of thumb? Are the local inspectors all asleep at the switch?

  5. user-2890856 | | #5

    Probably like NJ and other states Dana. They adopt a code but some localities do not enforce it . Don't quite know how that happens but the phenomena certainly exists

    To the OP , you cannot go wrong with EnergyDocs , Mike does really good work

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