There's no gaurantee that the higher bid would have used nitrogen or a micron gauge either.
I'm curious to know what percentage of Contractors do braze with nitrogen and use a micron gauge. Anyone know?
Most homeowners wouldn't know the difference.
The majority of homeowners don't know what a Manual J or Manual D is either so how many Contractors actually figure out those?
Also, if the existing system worked well, why pay extra to have a Manual J or Manual D done?
Anyway, I do not agree with just blindly going with the higher bid. They may be just like everyone else just higher priced.
Of course if the homeowner requests in advance that a Manual J and Manual D be performed along with the brazing with nitrogen flowing and vacuuming with a micron gauge be done, I'd bet the majority of Contractors might be afraid that the homeowner knows too much and raise their quotes significantly(to scare off the business) or not give a quote at all.
They can always go to the next unsuspecting homeowner who won't know the difference...
Now the next question is just how much of a negative affect does brazing without nitrogen do? I'd bet my 20 year old 3 ton Bryant A/C wasn't brazed with nitrogen, but who knows maybe it was?