People should trust their mechanical contractor and before they pick one, they should do a bit of background checking. References, licensing the BBB, etc, make sure the job includes an inspection by the city or state agency covering mechanical work.
The customer has to take on the responsibility of doing a bit of homework in picking a quality mechanical contractor.
You can find (online) more research on which coffee maker to buy, before the purchase is made, than on which contractor to use.
In the case of mechanical contractors, most of the research is done after the purchase was made, not before.
In addition you can always get a second professional onsite opinion.
There are not enough facts known.
It is like asking how much is 2+2+3+?+?+?
Answer unknown, without knowing the value of each of the ?
The only way to get the value of each of the ? Is by an onsite evaluation by a professional.
There are a lot of different issues that could be addressed in this particular thread. The discussion can be fun and interesting and maybe somewhat informative, but no final accurate diagnosis can be made though this forum on this question, hence the reason I stated more than once.
To diagnosis any possible problems, get a professional onsite (onsite) evaluation.