We have a Rocket Giotto v3 purchased in 2014.

It worked reliably for 3 years at our previous house which had tank (rain) water (in ground concrete tank/tile roof).
Since moving to our current location 5 years ago, also on tank (rain) water, it has displayed the 'green flashing light/no operation' syndrome.
Current house has a metal roof and above ground metal tank (probably with a lining).

A quick search for 'Giotto' on HB shows well over 200 pages of entries - the 20 or so I looked at did not resemble our situation.

The 'odd' thing about our green flashing light condition is that it 'clears up' after a trip in the car.

There have been several trips to a local technician about 12km away, and each time the result is 'No fault found'.

After a recent 'flashing light' episode, I circumvented the technician's fee and took the Rocket for a drive myself - it worked flawlessly for a month following that trip.

The time has come however. for a permanent resolution - as it's a heavy beast to lug to and from the car.

I am tempted to simply short the water sensor wire to earth permanently, as this should avoid any further trips.

However, I would love to hear if anyone else has experienced a similar situation where 'movement' resolved a 'green flashing light' condition.

I am loath the just replace the control unit and wiring harness without having localised the (intermittent) fault.

I mentioned all the water conditions above, in case people feel there are water conductivity issues underlying our situation.
Given the 'fault clearance' by movement, my gut feel is that water quality is not the issue - but I have an open mind.

Parts & Schematic

Ever descaled?

The tank sensor lead could be corroded if there is a slight leak.

bcollie wrote:Given the 'fault clearance' by movement, my gut feel is that water quality is not the issue - but I have an open mind.

I would first rule that possibility out. Try adding a tiny pinch of baking soda (sodium bicarbonate) to the reservoir to see if it goes away. Or check your water with an inexpensive conductivity TDS meter. I think you were probably OK with a concrete tank, but rainwater in a metal tank may not have enough minerals for the reservoir sensor to work reliably.

Irrespective of water sensor issues, rainwater would likely be a little more acidic and corrosive than you want in your machine. It would be better if you added a small amount of bicarbonate to the water. Not much is needed. A half teaspoon of sodium bicarbonate or potassium bicarbonate per 10 liters of water would get you to the ballpark of 40 mg/l alkalinity (acid buffering capacity) that is typically advised for espresso machine water.

Another possible cause is sometimes an airlock gets into the lower coupling because the white tub probe is not long enough to open the tank outlet stopper. Usually taking the tank in and out fixes it, or moving the machine as you found. I think Rocket used to supply a slightly longer metal probe for the white tub, or you can try;

- Putting a washer under the metal probe to raise it higher
- Unscrewing the plastic coupling from the water tank and using a spacer or teflon tape so it sits a little lower

Thank you for the link and suggestions Ian.
I had seen that doc you linked - our unit has a second gauge on the right hand side - a 'brewing' gauge I think, from reading through the group posts last night.
Haven't seen a correlation with our 'version 3' unit and a particular sub-model description (Premium, Premium-Plus...).
I'll have a close look at the wire connection to the tank sensor unit, looking for corrosion in connector or cable.

Thank you Pat,
I am looking into a TDS meter.
Will also try the Bicarb solution.

Thank you John,
Yes I noticed the sensitivity settings on a pic of the control box that the Technician sent me.
We'll try that adjustment. - it may compensate for change of water condition (if that is the culprit).

Thank you Mike,
Certainly good suggestions to overcome that electrical gap situation.