Small inner diameter, sturdy cord: the EPDM ring 3.37 × 9.21 mm
This O-ring stands out because its cord, at 3.37 millimetres, is almost as thick as its inner diameter of 9.21 millimetres is wide. Proportions like these are found where a small channel under pressure has to be sealed reliably and the groove is designed to be correspondingly deep. The part number is H.1.017.02.
The material is EPDM, the standard material for hot water and steam in food applications. EPDM stays soft for a long time and does not take on any off-flavours – in return, it does not tolerate oils and greases, which are not required anywhere in an espresso machine anyway. The only thing that matters is that the dimensions are right: a ring with the same cross-section but a different inner diameter will roll up during installation and will not seal.
When it is due
You will notice it at a spot that gets damp after heating up and stays dry when the machine is cold. Or by a pressure that no longer holds steady because something is escaping at the sealing point. When removed, the old ring is hard and glassy and shows flattening on two sides; sometimes it is also torn. A ring that can no longer be stretched to twice its size without tearing has done its job.
At a glance
| Type |
O-ring, round |
| Dimensions |
Cross-section 3.37 mm, inner diameter 9.21 mm |
| Material |
EPDM |
| Installation location |
Not specified in our documentation |
| Fits |
La Marzocco machines that list the number H.1.017.02 at this position |
| Scope of delivery |
1 O-ring |
| Part number |
H.1.017.02 |
| Version |
Original spare part |
| Brand |
La Marzocco |
| Installation |
Installation by a qualified technician recommended |
Important for installation
The ring sits in a pressurised connection. Let the machine cool down, disconnect it from the mains and fully release the boiler pressure before opening a threaded fitting. We deliberately do not provide step-by-step instructions here. Clean limescale and old residue out of the groove before inserting the ring, and check the sealing point again after heating up.
Who it is for
For service companies and technically skilled owners who work with the exploded view drawing and have identified the number H.1.017.02. Because of its unusual proportions, this is not a ring you should replace with one from an assortment box.
What goes with it
Other EPDM rings in our range are the O-ring 1.78 × 10.82 mm EPDM 70 ShA and the O-ring 10.77 × 2.62 mm EPDM 85 ShA – both have a similar inner diameter but a completely different cord. For the lever machine, there are the O-rings for LEVA in six sizes. For an overview, see Original spare parts and Accessories and spare parts La Marzocco.
From our workshop in Bern and Zurich
We never fit a new O-ring dry. A touch of food-grade silicone grease on the ring – not in the groove – prevents it from twisting or getting cut on the edge as it is pushed in. That is how we do it; it is not a manufacturer requirement. Afterwards we pull a test shot, ideally with Nutty Delight; for something sweeter, use Cozy Chocolate, for something stronger, Very Nutty. You will find more roasts under Coffee beans.
No returns
Original spare parts are excluded from exchange and return. They are sourced specifically for each order and cannot be resold after installation or a trial fitting on the machine. So before ordering, check the model, year of manufacture and serial number of your machine – or drop us a quick line and we will clarify the fit together. Your rights in the event of defective goods remain unaffected.
What does 3.37 × 9.21 mean?
The first number is the cross-section, i.e. the diameter of the rubber cord, the second is the inner diameter of the finished ring. Both values must be right, otherwise the ring will not hold.
What hardness does the ring have?
Our documentation does not state the Shore hardness for this position. The material is given as EPDM, nothing more is stated there – and we do not claim anything more either.
Will the ring fit my machine?
That is determined by the part number H.1.017.02 on your exploded view drawing. Otherwise, send us the serial number and we will check it before you order.
Is the ring food-grade?
This is an original spare part from the machine manufacturer for use in the water and steam circuit. We do not have any further certification details.
Can I pick up the part at your showroom?
Yes. We are in Bern at Gerberngasse 44 and in Zurich at Hagenholzstrasse 50b. Let us know shortly beforehand and the part will be ready for you.
Questions about the fit? Write to us at [email protected]. We deliver across Switzerland and to Liechtenstein in 2-4 working days.
