I have a LaCimbali M-29 Selectron that I bought used about 6 months ago. During back flushing the machine bubbles from the 2nd group head once I turn off the pump. This seemed odd so I took a look at the internal plumbing. Someone obviously did some after market plumbing inside the machine, or maybe this is an alternate configuration on the M29. My question is: Is there any advantage to being plumbed this way? Since this is a home machine I only use one group head at a time so the steam release into the other head is not an issue. Before I order the parts to return it to stock, I thought I would see if any of you had more insight on this.

Also, I am also curious what the other 3 way solenoid that pulls from the top of the boiler and is hooked into the drain line from the group 3 way solenoids is for.

That is actually probably a stock set up. Although i don't have my machine set up like that, take a look at this M32 which has the same plumbing form the 3-ways.

Thanks Trumz, yup, it appears the 3 head machine is plumbed like mine. After looking at some parts schematics, it appears to be an option. Maybe I'll just keep it this way. I still do not know what the three way coming off the boiler does unless it is an overfill or over pressure release. Machine has been disassembled descaled and put back together in the past 2 days. Next step is to add some sort of water filtration and maybe insulate the boiler.

Mokko wrote:... maybe insulate the boiler.

Do a search on this site about boiler insulation. There is lots of information out there and people have used all kinds of different materials. I would recomend it if you're planning to leave the machine on 24/7.

I think I am going to try simple foil covered insulation. I found it interesting that lots of people were really interested in Armaflex insulation. On their web page is specifically states to not use this product where temperatures exceed 220 deg. Boilers can easily be operating at 240+

Got the answer today. Turns out this was a machine built for the European market and the different plumbing and 2 way solenoid are part of a "dry run system" where steam from the boiler is released back into the group head after extraction to dry out the pucks. I don't think this is working correctly on my machine since I still get wet pucks so I am going to tinker with it some, and then probably remove it and go to US stock configuration where the 3 way off the group head drains directly into the drip tray.