Best Of
Re: Return/Condensate pump questions
Check valve between the pump and boiler is leaking back. I believe you supposed to have 2 of them 1 at the pump and another at the boiler.
Re: Return/Condensate pump questions
Unless there are emitters in the basement, returns below the boiler are easier to pipe directly.

Re: Flaring tools
Any of them will do double flare if you have the buttons to make the initial fold

Re: oversized water heater
250 if a very large tank, depending on the burner size it may be an ASME tank, worth some $$$ depending on the age
How is it vented.

Re: Burner technicians -what’s going on in this industry?
I agree with @GroundUp to an extent. There are plenty of losers in the union and out of the union. I ran a job with 8-10 pipe fitters and 4 sheet metal guys and one of the pipefitters feel asleep outside in the blazing sun. Probably had too much liquid lunch so I fired him on the spot. And he had just come back to work after being laid off for two years…….I wonder why!!!!!! And he complained no one would hire him!!! Guess riding the bench didn't teach him anything. And he complained that "black pipe is too hard" & "why wern't we using copper" It was a steam job!! We were an out of town contractor so the other local tried to stick us with him.
But you learn who the good ones are and there were a lot of them at least in my local. I learned a lot from them when I was young. Most of them did a good job and a decent days work.
Re: Burner technicians -what’s going on in this industry?
I was referring to HVAC. Installing boilers. Piping, soldering, wiring, controls, setup. Furnaces and air handlers. Knocking tin, testing SP, piping exhaust flue, running drains, leveling. The AV stuff IDK.

Re: oversized water heater
Suggestion…Replace the water heater with a properly sized water heater that will accommodate the needs of the occupants.

Re: Estimated life expectancy?
Sure Paul. Who taught you to talk that way to people you never met?
Re: What do you use and why?
AAA still has the "Trip Kit". but you no longer go into the AAA location and just ask for it. It is all online and you can order the book to be sent to you by mail or download it and print it out on your printer. Still has the turn by turn directions and the points of interest along the way. I still like the old flip books!
Re: oversized water heater
A 40 gallon water heater is sufficient for 3 people. How old is the large commercial heater?
Can you sell the AO Smith Commercial on the internet? They are not cheep so you can get a couple of hundred for a used one if it is not too old. Remember you paid retail for the tank and the installers, You are not gong to get anywhere neat what you paid for it. You will be selling at less than wholesale cost and the buyer needs to pick it up. Not like getting a new one delivered by the supply house.