Re-plumbing a boiler
I know this is more HVAC territory but I figure the plumbing folks would know more about pipe fitting.
I’m not sure why this is plumbed half in copper and half in cast, but it’s leaking in a few places and I’d like to clean it up. The weird zigzag with the shutoff at the bottom of the boiler is the bit that actively drips when the system cools off, but the outlet from the boiler on the top has plumbers putty on it so I’m sure it needs work too.
My questions:
Why did they use copper in the middle here? The system piping and the boiler connections appear to all be cast iron. I would repipe it all with cast unless told otherwise.
Is there anything special I should know about repiping this? I wasn’t sure if there was a particular reason the expansion tank is hanging off there to the side, or why the shutoff for the bottom of the boiler is oriented horizontally when it seems like it could have been put in vertically.
I recognize that the fittings are likely to be stuck on there pretty good but I think I can work them out with heat and PB blaster like I’ve done for other pipe fittings that were subjected to decades of outdoor exposure. The boiler is only about 20 years old and it’s a basic unit with very few components that works great so I’m not keen on replacing it anytime soon.