Duct design for light-commercial buildings
Manual Q duct design for commercial spaces.
Commercial ductwork carries more air, longer runs and more zones than a house. Manual Q sizes it from your Manual N loads so every space gets its airflow without oversized fans or noisy branches.
What it is
ACCA Manual Q is the duct design procedure for light-commercial, low-pressure, low-velocity systems. It sizes supply and return ductwork from the zone airflows in the Manual N load calculation.
It accounts for fan performance, fittings and duct lengths so the design works within the equipment’s available static pressure.
When you need it
Commercial mechanical permits usually ask for a duct layout alongside the load calculation, especially on new buildings and tenant improvements.
What we need from you
- Architectural plans with ceiling heights
- Manual N loads, or we run them
- Equipment selection or rooftop unit model
- Space constraints above the ceiling
What you receive
- Duct layout drawn on your plans
- Supply and return sizes with CFM per outlet
- Static pressure worksheet
“We here at TRG HVAC LLC have been using LoadCalcs for years now. Scott, Jake and Amy are absolute professionals. The turn around time for results are impeccable. I highly recommend the services offered by Loadcalcs! Thank you again for your help.”
Questions
What is the difference between Manual D and Manual Q?
Manual D is for residential duct systems. Manual Q is for light-commercial systems, which move more air through larger, longer duct networks.
Do I need a Manual N first?
Yes. Manual Q sizes ducts from the zone airflows that Manual N produces. We can run both.
Can you design for rooftop units?
Yes. Tell us the unit and its location and we design the distribution from there.
Fast estimates
Send the plans. Get an estimate.
Send us your questionnaire and plans, and we’ll get you an estimate right away. Reach out during office hours and you’ll hear back within 30 minutes, whether it’s an email, text or call.