I have no idea whether the electrical components work. So far I tested the switches and solenoid valves, and the seem to work.

For the fact that I have a boiler water level indicator I thought it would be fine for me to top the level manually.

Also by adding a pid controller and wiring the machine with it, I thought I could keep it as simple as possible.

Here is the main switch, I kept the whole wiring still on, to have some reference in case I needed it:

It has been a while since my last post, but the rebuild has been going great!

I managed to draw a decent wiring scheme, wire the Rancilio up and set some PID parameters.

I will post some pictures and describe the steps as soon as I have time but for now I was wondering if the machine doesn't have a checkvalve since the rotary pump and out braided hose get hot while the machine is not brewing shots. Here is a picture:



Am I missing something or is it the machine missing a checkvalve?
Thanks for the help

There are two check valves. One for each group at the manifold. They are circled in red below:


One of them could be back flowing, but when you are pulling a shot, the water should be flowing from the pump and to the group being used, regardless of whether or not the check valves are functional...

Looking at your plumbing, I see a third pipe coming off the manifold that I don't recognize. On the right side of your picture, you have the pump coming in through the flex line on the left of the cross fitting, the pressure gauge headed of the top of that same fitting, the feed tube for the manifold on the bottom and the fill valve to the right. The fill valve has the manual fill tube coming out the top and the auto fill coming out of the right side. Both of those connect to the steam boiler and could be weeping back through to the pump. On the manifold. It is fed from the bottom and has the two groups that are fed the the check valves at the top as mentioned before.

Then there is the curious 4th line exiting to the left. Is that just an expansion valve that empties to the drain cup? If it is, I'm uncertain how it can possibly do its job. In order for it to vent expansion pressure to the drain cup, it would need to see the pressure in both of the HX loops. As it looks now, both HX loops have check valves on them and all the expansion valve can see is cold water pump pressure. Perhaps I'm missing something here...

Anyway, not sure if you are plumbed or bottle-fed, but if it's the latter you can see if hot water is back-feeding through the pump feed line into the fresh water supply. That is a sure fire sign of a failed check valve or boiler feed valve seal. Checking to see which of the fittings in the inlet piping is warmest can help point you to the culprit.

Cheers!

- Jake

Thank you for the reply Jake_G, after looking closely I noticed the 2 check valves on the HX pipes.

And to answer the question for the 4th line (which is the one coming off left of the HX manifold) yes it drains in the drain cup, and I believe it can only act on cold water pressure coming from the pump. To be honest I haven't seen it expelling water once.

As you mentioned, there was no check valve from the steam boiler, and was backing hot water through the feeding line up to the pump. Since this is a commercial machine meant to pull shots consistently, there was no need for a check valve (I suppose) since running the pump for a few seconds brought all temperatures down.

However, since I am using it at home, I installed a check valve splitting the flex feeding line (from a one 100cm to two 60cm and 40cm). This solved the temperature issue, now that hot water can't make it back in anyway.

So far I am manually feeding the machine, until I find a strong and durable water filter to place before my tap water line (it is unbelievably hard, talking around 550ppm of total dissolved solids. I recently installed a 5 stages filtration system for the whole house, which brought the total dissolved solids count from 650ppm, to 550. In all honesty I hoped for a much bigger reduction and I am trying to understand why right now...) btw, if anyone is knowledgeable about it, feel free to pitch in...

The 5 stages filtration system uses 10inch filters which in order are: washable mesh filter for debris, a 10 micron Filter, water softener salts, activated charcoal, 1 micron filter. After installing it, the count dropped by 100ppm. to try and improve, I removed the mesh and the salts, adding one more 10 micron filter and another 1 micron. Results did not change, still 550ppm of total dissolved solids...