The solution to this problem was so simple, yet I wasted a lot of time making it difficult. A customer and his wife dropped a Breville BES 840 machine in and wanted to know on the spot if it was worth fixing. The wife was chomping at the bit to purchase a new machine she liked the colour of. So I told them it will cost them $45 or the machine for parts to find out if its worth fixing. They aggreed and I ran it up on the bench.
The BES 840 is a nice little machine but quite cheap to buy now so not worth spending big bucks on repairing.

There was no water pressure just as the wife had said, but that was because apart from a few mls of hot water being produced, steam was coming out both the hot water and group, nothing else. Now in these little single boiler machines, steam is produced from the coffee boiler or thermoblock to be more correct,  by purging the water from the boiler and then pulsing it in bursts which flash to steam in the hot boiler. When the machine makes water for coffee or hot water, it completely fills the boiler., leaving no room for steam production. So my initial solutions to the problem were;

    1. Insufucuent water flow to the boiler
    2. Boiler too hot
    3. Some sort of leak

I disconnected the pump and measured the water flow before the thermoblock. It seemed ok. I did the same thing after the thermoblock and the water flow was diminished and just steam was produced.  As I was on the spot I told the customers that the thermoblock was be full of scale. Go and buy a new machine. I could not see any scale on the entry or the exit pipes, where scale can cause restrictions. But he wanted a quick answer and that was it, oops.

So the machine was gifted to me. Now to repair it and actually make some money today. I changed the NTC sensor, not that I had any indication the thermoblock was too hot, but the Breville technician told me to on another similar job. It made no difference but on any thermoblock that’s possibly been overheated its good practise to change the NTC sensor.
I found I could blow through the thermoblock, so it had no scale restriction. This was strange. Just to make sure I tried a new thermoblock and demonstrated the fault with the new thermoblock. The themoblock was ok. This is good news as they are expensive to replace. I decided there were only 2 solutions/options remaining, the pump has some intimentient problem where its not delivering water volume adequately all the time, or the 3 way valve is leaking some water not allowing the thermoblock to fill correctly or a triac is locking on and over heasting the thermoblock. The last 2 solutions seemed unlikely.

So I changed the pump. Although I still got steam out the group and hot water dispenser, it was less, this pump was doing better. Then I really listened to the pump, the new pump seemed quieter than the old one but still louder than normal. Perhaps it is being starved of water, maybe the flow rate I measured was insufficient to fill the thermoblock. It did measure ok, but maybe it was an anomaly. So I looked for restrictions between the tank and the pump and there it was staring me in the face. Shit in the filter. Note the new filter next to the old one on the right in the photo.

breville filterYeah its obvious somethings not right when they are side by side but in my defence I get blinder everyday, I did look at the filter and it looked normal. Once removed I tried blowing through it and yeah it was just blocked enough to make the pump struggle. I had assumed the flow rate was not the issue as it measured ok so had mistakenly concluded the pump had a good water supply. As a good measure flush the flowmeter as well, they get full of debris.

Anyway, the lesson here is the simple solution is usually the correct one, check the obvious things twice and wear your glasses if you have bad eyes like mine. A blocked water filter is obvious. Usually I can hear an Ulka pump that is being starved of water, it was not until the new one was installed I noted the difference. Possibly I’m going deaf as well. Generally losing my edge. The pump was a contributing factor, it often is. When in doubt throw it out.

Anyway if you have a Breville single thermoblock machine that’s producing steam not hot water through the group, this may help.

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