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Refilling/purging X-2 boiler with no drain valve

magister Member Posts: 2
Hi everyone- thanks in advance for your input

I currently have a leak on a t-fitting on what I believe is the supply piping of my boiler and need to drain down my system to make the repair.

Before I do, I wanted to verify a few things and ask a couple questions. I’ve attached several pictures for reference.

1.) It appears that my cold water feed, back flow preventer, fill valve, expansion tank, and circulator pump are all on the the return. I’ve read conflicting information about how the circulator pump can be on either the return or supply side and just wanted verification that in my case, it is in fact on the return. I’ve also read conflicting information about feeding water into the supply vs return. Can anyone explain what's going on in my system?

2.) Since I don’t have any drain valve on my return piping before the ball valve, is there a way for me to effectively perform a forced water purge? I assume not, which is why I was thinking of soldering on a drain right above the ball valve on the 1/2” copper where the shark-bite cap is currently. Would this work? Other suggestions welcome.

3.) My plan was to drain down the whole system, sweat off the leaky brass t-fitting on the supply piping and replace, add a drain above the ball valve on the 1/2” copper, and then re-fill boiler, performing a forced water purge to get the air out. It all seems pretty straightforward, but I’m not quite wrapping my head around why water wouldn’t be pushed UP through the return piping during the forced water purge based on how my system is piped. Obviously, I would want the water from fill valve to travel DOWN into the boiler, circulate thru the supply piping and come back thru the drain I plan on installing, but what prevents the water from being pushed UP the copper return pipe when being introduced during refilling/purging?

Thanks for the insight- there’s probably an obvious answer here, but I’m feeling like a dummy right now.



  • Jamie Hall
    Jamie Hall Member Posts: 23,286
    Lots of options. Most of them good. As to the location of the pump, pressure regulator, and expansion tank -- either the return of the supply works, so long as the expansion tank is on the inlet side of the pump and reasonably close to it.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • magister
    magister Member Posts: 2
    Thanks for the reply Jamie- would soldering on a drain right above the ball valve on the 1/2” copper stub-out where the shark-bite cap is currently be ok? I want to perform a forced a purge after making the repair.