I have the Bel Aire 318VN installed and plumbed. I have some minor leaks that need attention and will try to tackle those before I put up pictures.
The wiring, plumbing, compressor siting, and cosmetics took 3.5 weeks. Each was about the same level of difficulty. The major failing in this installation was the horrible contingent the engineers and manufacturers placed on the end-user.
When I was a journeyman carpenter I would get a price from the job foreman for framing, stacking, joisting, drops . . . whatever; say $.05 per sq foot of slab. Many foreman would cheat with your work agreement. They would walk the unit after you had finished looking for things you needed to fix before you jumped the next unit. It would always be small details . . . drywall backing here, electrical chase here, teco clips here. By the time you completed all the work (and sometimes the foreman would catch you 2 or 3 units down the road with a fix). You were actually making about $.03 a foot.
This is the corporate culture of manufacturing and engineering today. They sell you a product then make it your responsibility to finish the design and purchase the necessary parts for installation. Some design and engineering is necessary but there is no incentive for the manufacturer to ensure it is minimal.
By the time you have designed it you have gone through several iterations. Each iteration can require a trip to the hardware/fitting supplier. By the time you add the gas, cost of the changes, and the time you’ll find you’ve added another $10% – 20% to the price.
Bel Aire was particularly guilty of this (not having any other manufacturer to compare I figure they are all like this). It took me 2 days to get the installation correct. For instance, they expect you to hook up the electrical from their switch box but do not give any attention to the conduit/cord connection with the machine. Thus, if you need to make the connection with a strain relief fitting you are left with stopping and going to the supplier. If you’re figuring is incorrect you have to do the same again until you get it right. They needn’t supply you with the stuff just design the box to preclude your becoming the engineer and manufacturer yourself. Many tool companies have bent over backward to ensure when you buy the tool you do not have to obtain a bunch of ancillary crap to gain efficient use. The premier example is Festool.