The medium-sized EPDM ring from the H.1.050 series
Twenty millimetres inner diameter, just under two millimetres cross-section: this is the size you find on larger screw fittings, covers and inserts. The ring sits loosely in its groove and is compressed when the parts are screwed together – that is the whole trick, and it only works as long as the material can spring back.
After years in hot water, it no longer does. The ring then stays flat, just as it was compressed, and the sealing point starts to weep. EPDM lasts a long time in this environment, but not for ever – and because the part is among the cheapest in the entire machine, it is the wrong place to save money.
When it is due
Moisture, a limescale ring or a drip appears on a cover or screw fitting. The removed ring is hard, can no longer be stretched or has a permanent flat spot. It tears when you pull it off. Or the sealing point is being opened for another job anyway – in which case a new ring belongs with it.
At a glance
| Type |
EPDM O-ring |
| Location |
Sealing point inside the machine; our documentation does not state the exact position |
| Fits |
Order by part number; our documentation does not name a specific model |
| Scope of delivery |
1 O-ring |
| Part number |
H.1.052 |
| Version |
Cross-section 1,78 mm, inner diameter 20,35 mm, EPDM, hardness 70 ShA |
| Installation |
Fitting by a qualified technician recommended |
| Brand |
La Marzocco |
Important for installation
The sealing point is inside the machine and may be under pressure. Before opening, the machine is depressurised, and a leak test afterwards is part of the job. We do not give step-by-step instructions here: the ring is a general item without a fixed installation location, and instructions without knowing the spot would be guesswork. If you are unsure, leave the replacement to a qualified technician.
Who it is for
For service workshops with a well-sorted stock of seals and for anyone who orders by number. This series is worth keeping as a small stock: three sizes in the drawer, and the most common sealing points are covered without the machine having to wait for a delivery.
What goes with it
The smaller siblings in the same series are the 1,78 × 10,82 mm EPDM O-ring and the 1,78 × 11,89 mm FKM O-ring. Large sealing surfaces are covered by the Viton group cover gasket. All other seals are in the Original spare parts section, the rest of the range in the La Marzocco accessories and spare parts section.
From our workshop in Bern and Zurich: If a cover still weeps after the seal has been replaced, we don’t replace the ring a second time but look at the groove first: a single hard spot of limescale in it keeps any new ring at a distance. Warm the groove through properly, wipe it out gently, and only then fit the new ring. This is our own routine and not a manufacturer’s specification. For the test shots afterwards we like to use Nutty Delight or Cozy Chocolate; you’ll find the full selection 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 once they have been fitted or test-fitted on a machine. So before ordering, check the model, year of manufacture and serial number of your machine – or drop us a line and we’ll work out the fit together. Your statutory rights regarding defective goods remain unaffected.
Frequently asked questions
Where is this ring fitted?
Our documentation lists item H.1.052 without an installation location. We won’t make one up. Tell us where the number appears in your service documentation and we’ll work out the position together.
Is 20,35 mm the inner diameter or the outer diameter?
It is the inner diameter. In addition, there is the cross-section of 1,78 mm, as is customary when specifying O-rings.
Can the ring cope with descaler?
EPDM is made for hot water and the usual descaling cycles. What matters is rinsing thoroughly after descaling – that applies to the whole machine, not just the seals.
How many should I order?
The price is per piece. Two are rarely wrong: one to fit, one for stock.
Can I take a look at the part at your shop?
Yes. Come to our showroom in Bern at Gerberngasse 44 or in Zurich at Hagenholzstrasse 50b. Bring the old ring with you and we’ll compare the dimensions directly.
Unsure about the size? Write to us at [email protected]. We deliver across Switzerland and to Liechtenstein in 2-4 working days.
