No boiler pressure on HX espresso machine - Bad pressurestat?

June 23rd, 2022, 9:11 pm

Machine is an Isomac Millenium (heat exchange). It powers on, the heating element seems to work as the machine and grouphead gets hot, but there is no pressure in the boiler. Gauge reads 0 and nothing from the steam wand when the valve is opened. I'm thinking this is a bad pressurestat, but I'm hoping someone more experienced can confirm that this sounds like the issue?

The pump is still working so I get water at the grouphead, but it's not up to temp. Anything else I should check before ordering a new pressurestat?

Any guidance much appreciated! Thanks.

#2: Post by **JRising** » June 24th, 2022, 9:53 am

If there's no pressure and you don't hear a massive leak from the steam boiler, then it may be getting hot, but it's not passing the boiling point.

It could be that the pressurestat is overheating due to the resistance of its own dirty contacts and failing. If the machine has a relay powering the element, it could be the relay overheating due to its own resistance. It could be that the element is cracked or burnt out such that it is grounded until it gets hot, then the slight expansion of the element allows it to insulate its filament.

If you're running it on a GFCI and it's not blowing that, there's a good chance it's not the element. Past that, the way to locate the issue would be to open the machine with it unplugged, and take off the body panels. Then you need an electrician friend or someone qualified to safely test the components in the element circuit for the "significant voltage drop". Please don't work on a live machine if you're not totally sure what you're doing. The walls are there to keep you safe.
There are plenty of places that can fix simple machines.

June 24th, 2022, 11:17 am

Thank you for the info. I unplugged and opened up the machine and one of the connectors on the heating element is burnt and melted. Does anyone know if this is indicative of a bigger problem? Or if I replace the connector and clean the terminals could it possibly be up and running again?

#4: Post by **Nunas** » June 24th, 2022, 11:40 am

dropbarsnotbombs wrote:<snip>Or if I replace the connector and clean the terminals could it possibly be up and running again?image

Quite likely, yes. This is a common problem that has been covered many times here on H-B. You need to cut the connector off and strip the wire back until you see bright, clean copper (the heat anneals the copper near the bad joint). Use a ratchet crimper and a quality connector capable of handling the current. Clean the lug on the heater with a wire brush, preferably brass.

#5: Post by **Pressino** » June 24th, 2022, 1:00 pm

Nunas is right. The burned spade connector definitely indicates a problem, but it's not clear exactly what the problem is. Replacing the overheated wire connector may allow the boiler to reach temperature, and if so great. I've seen cases where the problem is completely due to faulty connectors and fixing them fixes the problem. So it's always a good idea to start by replacing obviously bad connectors. If that doesn't work then the next step would be to inspect the heating element and the boiler insides for scale. Actually it's a good idea to test the heater element for continuity and resistance right after repairing the connectors and before actually firing up the boiler. A faulty heating element could cause overheating of its power supply connectors, but more often the problem is a loose arcing connector or something that caused overheating of the element itself (like a failure of boiler thermal and pressure limiting sensors. Let us know if simply repairing the damaged connector(s) fixes the problem!