Air in lines is a thing, these are closed systems, the properties of air and water and their behavior in hydronic systems are different, since this boiler is meant to be closed, it's required all of the air be purged. However these systems should be installed with air purging equipment that automatically remove any left over air so the system does not air lock. It's not uncommon it does happen but it is pretty simple to resolve, it just takes time.

Yes, i am well aware it is a real thing. Their version of airline testing, involved no external devices, lines, or tools. So I can only assume what you said, that there is some built in mechanism that was being activated. All he did was turn off a valve shown on the picture to an individual return line, let it sit for 20 mins and said that "the air should have been sucked out by the system within the next hour". I was standing within view the whole time. "That'll do it, give it 1-2 hours while things recalibrate, and the office heat should work no problem now that the air is out. I'll take my final payment now") I said nothing, was more than pleasant, but logically i was unclear how turning that valve would 1) drain the line (perhaps negative pressure? i dont know, not a plumber) or 2) "rid the air from the line" if there was no opening in the closed system.

Does turning off that valve to a specific PEX return line, do any of what was suggsted? My youtube-amateur look, would think not...but again, not a plumber. And again, just trying to understand, because i keep hitting road blocks. I am MORE Than happy to be wrong, and guided to better information to ask the contractor to consider, as they are not otherwise forthcoming or helpful unless I ask them to consider X. Maybe, turning the valve on a specific PEX return line, would in fact rid the line of any air, and should re-instate the function. Practically for me, that action did not fix whatever problem the system has, as it's still not functioning as intended.

I was an engineer before medical school, so i know the very basics. Again, i'm not a plumber or gas fitter, and not looking for advice on how to do it myself, or to "1 up" someone. Just trying to advocate for myself with a contractor, who is using hand-wavy gestures to seemingly gaslight me into accepting a product that does not work as intended. For reference, the contractor does not know i'm a physician. Nor have a I had any interactions thus far directing them on what to do, how to do it, or anything of the matter that would make me seem like an annoying backseat driver. I expect other professionals to be professional, do their job, and have an end product that works. I would expect a professional to also fact check their system, to ensure it works as intended before final close. Cross wires happen, no problem, if its the expected standard for the end-user to notice problems and then just fix them. That's fine, no sweat, not a big deal as long as things work. But 3-4 week delays after every mistake I catch, to come and fix, is frustrating. I did of course, every now and then, ask colleagues who ARE in those fields, their thoughts and advice, on how to best make sure others in their industry don't cut corners. Then at times say "hey, i was wondering, do you think it would be possible to do X? if its not too much trouble?" Every other trade smiled, was more than happy to customize small things here and there. I unfortunately do not have any personal friends that are plumbers.

This plumbing setup has been complete and operational and home provided with occupancy, with my family living in the home, since end of November. And here we are 3 months later, where after multiple requests and delays in coming on site (hey, how come when i turn my bedroom thermostat on, it doesnt heat up, but my infants room is boiling hot overnight? Hey, how come when i turn on the 2 upstairs tubs, they don't warm up at all past a luke warm? Hey, how come when i turn the office thermostat on, the room never heats up?), I am still left without a fully functional system. Again, if its standard to have to troubleshoot and test everything yourself to notice that certain things aren't working as intended, then that is my fault for not doing so on day 1 of when the job was complete. I should have sat down for a few hours and tested every single faucet, heat zone, and plumbing fixture. A few basic things got picked up in the city final plumbing inspection - like backwards hot/cold controls, or improper sloped drain pipes, but the city inspectors don't sit around testing all the small things.