Broken steam boiler drain plug

[MDL]

Yesterday I broke off the drain nipple on the steam boiler of my 2007 Vivaldi II. I was replacing the cap after descaling with vinegar and I broke off the nipple.

When I spoke to Chris Coffee service this morning they suggested tapping the inside of the drain and installing a plug. Has anyone done this so that they can suggest the appropriate size tap and plug to use? I would imagine that this is a balance between preserving metal for strength and getting enough thread to hold the plug against the pressure?

Thanks for any advice,
Mark

[chas]

Condolences. There are probably folks out there more experienced at this type of repair than I. When the nipple broke off was there any cracking in the surrounding metal. If so you probably to use a drill bit large enough to open the hole beyond any cracking. Before doing that I'd check for the sizes of available taps and be sure you have the drill bit, matching tap size, and correct size replacement stainless steel bolt before you start.

[MDL]

Thanks Chas. I am going to talk with a local espresso repair shop that has a good reputation. If they can take care of this for me I'll pay them to do it since I am not really setup to do it well; I would have to buy the numbered bit, tap, tap wrench, etc. and I have not done any work like this in over 30 years.

I'll let everyone know how it turns out...

[chas]

Good idea. Otherwise, you might end up spending as much as buying a new boiler.

[MDL]

I seem to have completed a successful repair. Following advice from the repair folks at Chris Coffee I used an 8mm 1.25 thread pitch tap on the inside of the steam boiler drain nipple. A stainless bolt wrapped with a good bit of Teflon tape and an O ring seem to seal the drain adequately. I will see how it holds up over time but it certainly held pressure after I put things back together.

[alsterling]

MDL... I just private-messaged you re "boiler leak issue" on my original S1, bought from Chris Coffee in 2006. I pulled that drain plug yesterday thinking it was leaking, only to find out my issues were at the top-end with what I think would be called a "vent-valve?" It's the small pressure sensing valve that slides up, with a very small O-ring that, when the boiler develops enough low-pressure, seals. I replaced the O-ring, although worry that my ring from the hardware store won't be for that high temp (?), but upon reassembly, had a "gusher" stream of water during the warmup cycle with the pump running. It was from the tall pressure relief (?) valve I'm pretty sure. I'm going to pull it, and while the machine is open, wonder if I should just pull and mechanically descale the boiler. I'd like to chat with you as you're local to me; So. Orange County. Hope to hear from you.......

[gschroeder81]

I recently had this issue as well. Went to tighten the drain cap and the nipple broke off.Also had a right-angle fitting break off, but I was able to salvage the threads by cleaning the bits out and chasing it with a 1/4" BSP Pipe Tap.





The Fix. I thnk I used M7, but M8 would probably be better.


I also used a SS bolt with teflon to seal and haven't had any issues.