Why won't HVAC contractors follow my Manual J report?
Contractors routinely dismiss independent load calculations and insist on using old rules of thumb or installing oversized equipment instead. This leaves homeowners unable to find someone willing to install the correct size system for their home.
What people tried
Every workaround mentioned in the threads below. We haven’t tested any of them — and nobody here is claiming they worked.
- 1Searching for small, local companies instead of big-name operations
- 2Consulting friends who work in the HVAC trade for second opinions
- 3Bringing up independent testing reports during initial consultations
- 4Getting multiple quotes from different contractors
- 5Calculating manual J loads independently
In their words
Unedited, most upvoted first, each linked to the thread it came from.
“However - every contractor we bring in for an estimate is arguing the findings in the report.”source ↗
“I have met with six or seven different people - some show absolutely no interest in even reading the report.”source ↗
“so I am kind of pulling my hair out trying to find a contractor who will follow the recommendations in the report and take the job.”source ↗
“Every contractor who has bid on my project bids a 2 ton system. some of them use the old rule of thumb of 1 ton/400 sf which isnt appropriate for a small highly insulated modular house that is pretty tight.”source ↗
“Some of them tell me they cant get anything smaller than 2 tons.”source ↗
Where this came up
People with this problem also raised
- 2Contractors asking for admin access but not knowing basic IT
- 36Why are contractor and window replacement quotes so absurdly high?
- 54How to handle a bad contractor who won't fix poor work
- 4Why are project deadlines and estimates always wrong?
- 3Getting disciplined at work for missing billable hours targets
- 2Can you change builder plans after construction starts?