GBA Logo horizontal Facebook LinkedIn Email Pinterest Twitter Instagram YouTube Icon Navigation Search Icon Main Search Icon Video Play Icon Plus Icon Minus Icon Picture icon Hamburger Icon Close Icon Sorted

Community and Q&A

DIY HVAC Design Results

nynick | Posted in General Questions on

I went and spent a few hours inputing the BetterBuilt HVAC design specs for my upcoming renovation. It’s not exactly perfect but pretty good. For instance it really doesn’t allow for the vagaries of different insulation levels or types of doors, but I got creative and input sliding doors as windows, for instance. It does allow for different U Factors and how many people living in the house and stuff like that, so that’s a plus. And it changes everything every time you change one little thing. Pretty cool.

I took a screen shot of the results. I don’t really know what they mean with regard to Heat pump sizing, zoning etc, but I was planning to have a ducted system throughout.

Maybe with a little more probing I can come up with BTU’s per room so I could then extrapolate 1st floor, second floor, basement and sunroom zones.

Anyway, I guess this is progress. Now if I only knew what it meant…lol.


GBA Prime

Join the leading community of building science experts

Become a GBA Prime member and get instant access to the latest developments in green building, research, and reports from the field.


  1. nynick | | #1

    I've made some preliminary comparisons after refining the Better Built HVAC sizing tool for my house renovation versus the Trane Short Form the HVAC subcontractor supplied to my GC. It's a little complicated because the subcontractor left out the proposed conditioned basement, but here are some details:

    HVAC TOOL: Sunroom 5607/5613 Heat Load/Cooling Load
    Subcontractor: Sunroom 10,926/10,310
    HVAC TOOL: 1st floor 17,444/9809 Heat Load/Cooling Load
    Subcontractor: 1st floor 26,805/29,355
    HVAC TOOL: 2nd floor 8083/4002 Heat Load/Cooling Load
    Subcontractor: 2nd Floor 9719/8135

    The subcontractor is quoting Mitsu-Hyper Heat units as follows:
    18K BTU Sunroom AH
    24K BTU 1st Floor AH
    for 42K BTU HP 1st floor and sunroom

    18KBTU 2nd Floor AH
    18K BTU HP

    60K Total with no basement figured in.

    The HVAC sizing tool with a sf of 4286 including the basement comes in at about:
    24K 1st floor AND sunroom
    8K 2nd floor
    13K basement

    What do you pros think? I can post the reports if they will help. Thanks

    HVAC Sizing Tool Results:
    4286 sf
    New Haven, CT
    Heating: 44,000 BTU/hr
    Cooling: 22,400 BTU/hr
    Latent: 7,600 BTU/hr

  2. paul_wiedefeld | | #2
    1. nynick | | #3

      I haven't. This is a total down to the studs renovation where we will be replacing the heating system totally and installing new insulation, windows etc. There are no ducts, we have steam heat and no A/C.

      Pretty much a ground up job.

  3. brian_wiley | | #4

    Definitely no expert, but since it’s a total gut job renovation it seems like a Manual J would be necessary. I also think it’d be pretty easy to do as you’d have all the values handy to input into the software. That’d also give you a breakdown of the floor-by-floor and room-by-room needs so that you could accurately size the equipment.

Log in or create an account to post an answer.


Recent Questions and Replies

  • |
  • |
  • |
  • |