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

Is this a good HVAC design?

Rick Fetter | Posted in Mechanicals on

I would like comments on the Manual J & D that was done for me and the duct work design that is attached. My house is located in zone 5A at 3160 elevation.

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.

Replies

  1. Ethan Foley | | #1

    Taking a very brief look at it, the simple answer is no. The design static pressure the designer has used is 0.51 in.wc. Your unit can supply a maximum 0.36 in.wc. This is a major error.

    Other criticisms might include:

    Don't use flex duct when hard sheet metal ducting would be a much better substitution.

    Don't take branches off the end cap of a trunk. This makes the trunk very difficult to balance.

    Drawing too much return air from the master suite, the additional air needed can't flow through a typical door undercut.

    The CFM specified is not an actual flow rate produced by this unit.

    That's my takeaway from a brief look.

  2. Jon R | | #2

    Ask them what sensible heat ratio (this effects humidity) you are going to get at 1/2 load (a much more common operating point than 100% load) and let us know the answer.

    The ducts are under-sized. Consider moderate over-sizing of all of the ducts. This will reduce fan power, improve balance as flow changes and provide additional flexibility in adjusting balance.

  3. Rick Fetter | | #3

    Thanks for your reply but I cant get the designer to respond to me now. Dana Dorset gave me the information on the Fujitsu unit but I am not an HVAC guy. I am a little surpprised at the lack of response to my question, I will put this in the mechanical section. I hope someone will respond with some more detailed information and contact info that we can correspond. ( not sure that allowed on GBA)?

Log in or create an account to post an answer.

Community

Recent Questions and Replies

  • |
  • |
  • |
  • |