Auto-size HVAC from Detailed Mode

2 posts / 0 new
Last post

Hello everyone. I'm working on a baseline 2-story residential model
using PTAC's for LEED. I'm having problems complying with the unmet
hours in several locations. I have commercial cooking equipment and
laundry machines as my only large loads. I have entered my calculated
heating and cooling capacities and my calculated CFM for each space into
detailed mode. To help with my unmet hours, I bumped my sizing ratio up
to 1.25 and set my throttling range at 6. Still high unmet hours. I
was wondering if there is a way to switch heating and cooling capacities
back to auto-size from detailed mode or do I just have to bump my
capacities up until they cover my hours?

Weekly, Ashley's picture
Joined: 2011-09-30
Reputation: 0

Hi Ashley:

Don't know what is "legal" in LEED, but try reducing your semsible loads
fraction for the kitchen and laundry down (say to 0.1). Perhaps assuming much
heat goes out the exhausts for these items.

Also, increase your HVAC airflows.

Worth a try.

John R. Aulbach, PE, CEM

John Aulbach's picture
Joined: 2011-09-30
Reputation: 1