Experienced installers can size a lot of houses by feel and get away with it most of the time. But “most of the time” is not a reputation, and more jurisdictions now ask for Manual J, S and D before they issue a permit.
What a design partner gets you
- Accurate take-offs. Equipment and duct sizes come from the design, so your bid reflects the job, not what usually works.
- Permit-ready paperwork. Where the building department asks for it, you have it. Where nobody checks, you still built on real numbers.
- Fewer callbacks. Right-sized systems with designed ducts run longer, steadier cycles and generate fewer comfort complaints and warranty trips.
- No scramble mid-bid. Builders often do not mention that the jurisdiction needs J, S and D until after your quote is accepted. A partner already in place turns that into a quick order, not a crisis.
- No software or staff to maintain. For most shops, outsourcing costs less than licensing design software and training someone to run it.
Bill design separately from installation
Builders often ask for load calculations before any install contract exists. Treat that design as its own scope of work with its own price. Once a builder has the documents, anyone can bid the installation from them. If the design is bundled into an install you never win, you paid for someone else’s job.
If a builder needs a number before the design is done, give a budget estimate and say so clearly. Without sizing and a duct layout, it is a placeholder, not a bid.
Replacements are where it matters most
Changeouts are where rule-of-thumb sizing does the most damage, because the old unit’s size gets copied forward. A Manual J from a sketch, measurements and photos is often all it takes to right-size the replacement.
How contractors work with us
Send plans by email, get an estimate right away, and get the same designers on repeat work. Several of our contractor clients send projects every month. We do not sell equipment, so we select from the line you carry and never compete with you.
“This is an outstanding company to work with. We have several Manual J, D, S done by this company on a monthly basis. Always responsive and hit deadlines. Not to mention their work is top shelf. I will use them for all my future load needs.”
Next step
Your load calc department, without the payroll.
You sell and install. We size and document. Send plans or a sketch, get permit-ready Manual J, S and D back, and keep your crews on jobs instead of waiting on paperwork.
How we work with hvac professionals