Giotto Rocket (2009) - thinks it is out of water but it's not

[Jonny]

Hi fellow coffee lovers,

I am new to this forum so I hope I am not asking something too obvious. I've done a fair bit of searching and tried a few things but haven't managed to crack this case.

Machine:
Giotto Rocket Premium - 2009 model
Tank model - not plumbed

Issue:

1. When I turn my machine on from a cold start, it fills the boiler fine then begins to heat up. So far so good.
2. After it has heated up it flashes the "low water" light and turns off the pump. Sometimes this happens during heat up and sometimes during the first brew.
3. I've found that when I remove the water reservoir (half full) the light stops flashing and the machine heats up. When I put the reservoir back (half full) the light starts flashing again.

Other relevant information:

• I've been using the machine without a hiccup for the last 2 years using the same water supply. I'm using tank water. I've tried using filtered and non-filtered rain water.
• Every function on the machine appears to be working fine other than the low water sensor. i.e. if I earth the low water sensor the machine brews and steams like a dream.

What I've done so far:

• When I earth the white "low water" cable the light stops flashing. This seems to indicate that the low water cable is fine and the controller box is functioning as expected. I've brewed a few coffees with this cable earthed (making sure there was plenty of water in the reservoir and it was feeding through to the boiler) and it seemed to operate without any problems.
• I've checked the connectivity of the low water cable (white one) with the controller box. I read around 2-3ohms resistivity when measuring the probe on the side of the white reservoir cup to the connector on the controller box.
• I've checked the resistivity between earth on the power cable and the large probe inside the white reservoir cup and it reads around 1-2ohms.
• I've checked the resistivity between the large probe inside the white reservoir cup and the machine chassis and it reads around 2ohms.
• I've removed the white reservoir cup and rubbed the middle and side brass probes clean. I've removed the small brass valve inside the reservoir base (beneath the spring) and rubbed it clean then re-checked resistivity.
• I've descaled the machine twice.
• I've checked that all connectors and firmly plugged in to the controller box.

I have found that I can reliably reproduce the issue by simply pushing the reservoir in place. Once I lift it out again, leaving the white cup full of water, the light stops flashing. It seems like the reservoir being in place somehow increases the resistivity and triggers the low water sensor but I can't see how this would happen or what I can do to fix this.

I am very appreciative of any advice. I'm happy to take to a repairer if its not something fixable myself but we live in the sticks so I'd rather avoid a long drive or hefty postage costs if I can :-)

Thanks, Jonny

[TC]

Hi Jonny,

The base of the tank (which enters the coupling) can be unscrewed. Unscrew it enough to increase the overall length by about 2mm. Teflon tape can be used to ensure it seals. This should attend to the problem.Another alternative is to fit a slightly longer probe into the tank coupling.

Good luck.

Chris

[Jonny]

Hi Jonny,

The base of the tank (which enters the coupling) can be unscrewed. Unscrew it enough to increase the overall length by about 2mm. Teflon tape can be used to ensure it seals. This should attend to the problem.Another alternative is to fit a slightly longer probe into the tank coupling.

Good luck.

Chris

Thanks Chris, I'll give that a try and will let you know the outcome.

Hi again Chris, I have tried that and a number of small increments either side but to no avail. I found one spot where it made one coffee ok but then started flashing shortly afterwards. Surely it shouldn't be that touchy should it? Or is this a commonly known nuance of the Giotto Rockets?

[Jonny]

Hi Jonny,

The base of the tank (which enters the coupling) can be unscrewed. Unscrew it enough to increase the overall length by about 2mm. Teflon tape can be used to ensure it seals. This should attend to the problem.Another alternative is to fit a slightly longer probe into the tank coupling.

Good luck.

Chris

Hi again Chris, I've spent the morning iteratively unscrewing the spacer on the bottom of the tank in about 1/5 turns at a time, re-inserting and testing. The length of the pour before the water cut off changed but I never found a spot that worked consistently for more than around 5-6 seconds. I suppose the longer probe is my next best option. Do you know where I can buy one of these?

Thanks again for all your assistance. Greatly appreciated.

Jon

P.S. Thanks again for getting me hooked on home roasting after your excellent roasting presentation in Mansfield a few years ago. I've been enjoying the joys of freshly roasted coffee ever since.

[TC]

Hi again Chris, I've spent the morning iteratively unscrewing the spacer on the bottom of the tank in about 1/5 turns at a time, re-inserting and testing. The length of the pour before the water cut off changed but I never found a spot that worked consistently for more than around 5-6 seconds. I suppose the longer probe is my next best option. Do you know where I can buy one of these?

Thanks again for all your assistance. Greatly appreciated.

Jon

P.S. Thanks again for getting me hooked on home roasting after your excellent roasting presentation in Mansfield a few years ago. I've been enjoying the joys of freshly roasted coffee ever since.

My pleasure Jonny!

Your machine thinks it has no water. Clean the probes in the coupling. Assuming sufficient TDS/ionic content in the water, you need to conduct a charge across these two probes. If there's no water there- open circuit and the pump is cut. It could also be that your water is not able to conduct a charge because it's too pure. The only other reason will be that the probe in the coupling is not allowing sufficient flow of water from the tank- which is why I suggested the adjustment.

Indulge me and try a pinch of salt in the tank and let me know how you go


Chris

[Jonny]

Hi again Chris, a week has gone by and a pinch of salt later I am back on the brewing train! So far it hasn't missed a beat so I'm guessing that means my water conductivity was the issue? I don't dare remove the water reservoir though in case the problem comes back :-)

[sejanus]

When I was using the reservoir I had better luck just leaving it in, and pouring into it.

[Jonny]

When I was using the reservoir I had better luck just leaving it in, and pouring into it.

I totally agree Sejanus and I have left it in for most refills but every few weeks I like to remove it totally and give it a good clean. The last time seemed to give me a lot more trouble than in previous times. On the bright side I ended up getting to know my machine a lot better as a result :-)

[Jonny]

Quick update a month down the track. I've had the same issue 1 time since but again I sprinkled a tiny amount of salt in the tank, re-seated the tank in the machine and hey presto, it was working again. What a classic first world problem when the water you're using is too pure!