A ball for two francs – and the tank breathes again
For the pump to draw water from the tank, air has to flow in behind it. That is what the tank vent is for, and inside it sits this small ball: it lets air through in one direction and closes in the other, so nothing sloshes out.
If it sticks, scales up or loses its shape, a vacuum builds up in the tank. The pump gets louder, draws air, the extraction stops – and troubleshooting usually heads in the wrong direction first, namely to the pump.
When it is due
The pump gets loud during extraction and audibly draws air, even though the tank is full. The tank can only be pulled out against resistance, as if it were stuck. When removed, the ball is scaled, discoloured or no longer round. Or you are servicing the tank connection anyway and replace the part as a precaution – an easy decision at this price.
At a glance
| Type |
Valve ball for the tank vent |
| Installation location |
Vent on the water tank |
| Fits |
Rocket. The item description available to us does not state which model series this number covers – please check before ordering. |
| Scope of delivery |
One ball. Valve housing, tank connection and seals are separate items. |
| Part number |
C430003819 |
| Version |
We have no documentation on the diameter and material for this number. |
| Brand |
Rocket |
| Installation |
Installation by a specialist recommended |
Who it is for
For anyone whose Rocket suddenly draws air when running from the tank – and for service workshops that take the small parts along when servicing the tank connection instead of travelling out twice.
Important for installation
The vent must never be bypassed, taped shut or fixed in place – it is not something to adjust, it must be able to work freely. A blocked vent means a vacuum in the tank and the pump running dry. Disconnect the machine from the mains and depressurise it before working on it. We recommend installation by a specialist and deliberately do not give step-by-step instructions here.
What goes with it
The tank lid including plastic insert, the large seal for the water tank, the bracket for the water tank and the Rocket accessories and spare parts section.
From our workshop in Bern and Zurich
Our routine, not a manufacturer specification: when a tank machine starts drawing air, we look at the cheap parts first – filter, tank connection, vent – and only then at the pump. Nine times out of ten it is something that costs less than ten francs. And we fill the tank with treated water, not hard tap water: what never scales up doesn't need replacing. Then the control shot – Nutty Delight is our standard, Cozy Chocolate the sweet cross-check, Very Nutty the candidate for milk. More in Coffee beans.
No returns
Original spare parts are excluded from exchange and return. They are procured specifically for your order and cannot be resold once installed or test-fitted on the machine. So please check your machine's model, year of manufacture and serial number before ordering – or drop us a line and we'll clarify the fit together. Your rights in the event of defective goods remain unaffected.
Will the ball fit my Rocket?
The part number is C430003819. The description available to us does not state which model series it covers. Send us your machine's serial number and we'll check before you order.
What diameter is it?
We have no information on this, and we won't claim anything here. If you need the dimension, we'll ask for you.
Can I seal the vent if it drips?
No. A vent must work freely. If it is taped shut or fixed in place, a vacuum builds up in the tank and the pump runs dry.
Is the valve housing included?
No. Only the ball is supplied. Housing, tank connection and seals are separate items.
Can I see the part in your showroom?
Yes. We are in Bern at Gerberngasse 44 and in Zurich at Hagenholzstrasse 50b. Bring your machine's serial number and we'll check the fit together at the counter.
Questions about the fit? Write to us at [email protected]. We deliver across Switzerland and to Liechtenstein in 2-4 working days.
