I have an Isomac Relax (HX) that I bought second-hand and in rough shape that I fixed up about a year ago. Now it runs the pump for ~1 minute than turns off.

When off, if I open the hot water spigot, little/nothing comes out, even if I tip the machine, which suggests that the boiler is actually empty. If I open the hot water spigot, a little bit of water comes out, but not as much as I'd expect. If I run the group while it's pumping, I get a fairly normal volume of water out which suggests that the pump is ok. I suspect that the solenoid valve that fills the boiler is bad.

Here's the schematic.

https://www.espressocare.com/assets/upl ... mplete.pdf

The solenoid valve in question is part 41.

The other concern I have is that there is some scale leaking from the fittings. I need to get the boiler out in order to get to the solenoid anyway, so I was thinking about descaling it, cleaning up the fittings, and replacing the heating element while I'm at it.



I'm posting for a sanity check. Does my diagnosis make sense? Is there anything else I should try or check before digging in?

Thanks!

Edit: Solenoid valve does become somewhat magnetic when the system is running, but that doesn't rule out a clog there.

Love the schematic. Very nice.

Your diagnosis makes sense. Pump tries to fill but times out and stops. Solenoid seems the most likely culprit. If there's nothing obvious when you open it up, check all the parts from tee number 43 to the boiler.

Before you start, might be worth checking the resistance between the level probe and the boiler, it should be 'OL' indicating the probe isn't submerged. If you get a resistance, something else funky is happening.

Its unlikely the boiler is empty, hard to do by accident. The hot water spigot relies on there being decent pressure in the boiler to push the water out, tipping the machine when cold won't tell you much.

If you take out the fittings you show with the scale deposits around them (boiler fill and tea water?), they need to go back in the same orientation as they are currently to fit the piping, which may not be fully tightened. It can be a little tricky to get the right amount of thread sealant in there to create a good seal at the required orientation, which is why they are the way they are now. Keep that in mind. Also, don't forget to order a new gasket if you're taking the element out.

Thanks for the tips!

The boiler water level was low. I had drained a lot of water while troubleshooting. It was the solenoid valve sticking. I was able to get it opening again with a little bit of percussive maintenance. I don't entirely trust the fill sensor. Before, it was giving me an open circuit. After I got the solenoid open, the boiler actually filled (the pump sounds very different when it's running near peak flow). Now the fill sensor causes my crappy multimeter to flash between open circuit and low resistance. I should borrow a Fluke from work... Regardless, I can pull it out and descale it pretty easily without pulling out the boiler.

I'm planning on just replacing the element along with the gasket because they aren't too expensive and I don't want to have to make a decision and have to wait a week when it is already apart. I only spent $300 on the machine and don't feel bad sinking another few hundred into restoring it.

The parts I need are:
solenoid valve
element
element gasket
fill sensor (it gave me problems in the past and is probably why I was able to get it so cheaply).
vacuum breaker valve (it doesn't have one)

I unfortunately won't have time until mid-June to do a full teardown.

So I've got the Isomac cleaned up and back together. It's always been pretty slow heating with pretty high duty cycles, but the heating element burned out so I replaced it. It heats up much quicker and has no issue maintaining pressure now while providing steam.

When running with the case off, there a barely audible steam leak near the heating element. I don't see anything bubbling out and it stays dry when cold. Should I take the element back out and wrap the threads with teflon tape, or should I not worry about it?

Also, That thing was a pain to get out. I had to use vice grips, a pipe wrench, and a hammer to break the cement that sealed the old one in.

There is some scale on the outside of the old element.

If you replaced the red rubber gasket with a new red rubber gasket, and it looks like you did, I would recommend a white Teflon gasket like the one Stefano sells, rather than try and make tape work.

If you get a Teflon gasket, tighten it reasonably, wait a half hour, give it another 1/8 or 1/4 turn. Problem solved permanently.

If the elbows leak, try thread sealer. Teflon tape did not work for me.

I used one of Stefano's teflon gaskets. I've been periodically tightening it. I seem to be able to get another few degrees each time I try. Nowhere near a full 1/8 turn.

I'm more curious about how much of a leak is considered acceptable because it looks like scale buildup on the outside of fittings happens with these machines even on factory installed parts.

Exordium01 wrote:I used one of Stefano's teflon gaskets. I've been periodically tightening it. I seem to be able to get another few degrees each time I try. Nowhere near a full 1/8 turn.

That should be good. The teflon deforms when it's first under pressure, so a little more tightening should take care of it.

Exordium01 wrote:I'm more curious about how much of a leak is considered acceptable because it looks like scale buildup on the outside of fittings happens with these machines even on factory installed parts.

Indeed, a curious thing. Welcome to the world of hand built espresso machines made in small factories in Italy, none of which are owned by Toyota.
I wouldn't consider such leaks normal, I fixed them when they appeared on my machines. It is not, however, very unusual to encounter them.

You're right. One more crank did it. The boiler has always been a bit noisy, but after getting it back together, this thing is silent!

Excellent! Another Isomac inexpensively brought back to life through some learning and a little elbow grease.