Gaggia TS Over Pressure Valve Modification (OPV)

My Gaggia TS needed a new pump (it uses an Ulka EP5, but I fitted an equivalent Olab pump as I had one in stock).  Great, a quick repair, but I managed to break a small black cap on the end of the OPV which bleeds off water when you are running hot water through the brew group.

Here is the sorry part.  As you can see I have snapped the hose barb off the side.

I was not able to source the part online, and not wanting to delay putting everything back together, so I tried some bodges to reconnect the hose.

A piece of thin tube, forced into the remaining hole in the side of the main body might have worked, but with what I had to hand, I tried to fit a barb to the end of the fitting, sealed with silicone.

After a few failed attempts (the fitting weeped slightly overnight), I decided on a more satisfactory repair was necessary.  Wife is making comments at this stage that the dinner table needs clearing of spanners, etc at this point.

Here is my modification:

The part on the left is the original main body of the OPV, which is fitted on to the outlet of the pump.  The pipe point upwards goes to the boiler tee-piece.

On the right I have soldered a nut from a 15mm compression fitting.  These have a 1/2″ BSP thread, which is reduced with a 1/2″x1/4″ adaptor to take the hose barb fitting.

The OPV can still be adjusted by removing the hose barb and inserting a 5mm allen key through the adaptor to reach the adjuster.

To solder the nut, I removed the internal adjuster, spring and seal (count the turns until the nut is free so you can set it to the same setting on reassembly).

I then filed the faces of the OPV and the nut until they were flat and bright, applied flux, and soldered with lead free plumbing solder.

Once thoroughly cooled, I cleaned the fitting with a wire brush to remove any remaining flux and assembled using PTFE tape.

The plastic tee-piece in the silicone water hose needed to be re-arranged to minimise any kinks in the OPV hose.  If I had some more hose of the same size, I would run the hose again with more slack.  Anyway, it is done and is drip free.

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15 Responses to Gaggia TS Over Pressure Valve Modification (OPV)

  1. Geoff says:

    I’d like to do this to my ts, is it easy to access the opv?
    Lots of good info btw.

    • admin says:

      Hi Geoff,

      Thank you for your comments.

      I didn’t actually adjust the OPV, but I think it should be easy. The difficulty is reaching the OPV, without burin g yourself on all the hot pipework.

      My photos don’t show the end cap on the OPV as I broke the cap removing it. Anyway, you pull the black cap off your OPV and insert a 6mm Allen key, adjust slightly (clockwise = higher pressure), refit the cap and then remeasure the pressure. Each time you remove the cap I imagine plenty of water then drains from the hoses into the TS – it is a good job it stays warm in there to evaporate it all. Obviously unplug whilst you are in there.

      The front panel pressure gauge shows the boiler pressure, this is not the pressure you need to measure. You will need a portafilter with a built in pressure gauge. I have a vested interest here as I sell them on Ebay (you could search for Gaggia Pressure Tester). I am trying to find replacement black caps for the OPVs, and hopefully will have some in a month or so.

      I measured my TS the other day, and it was registering 9 bar on the gauge. I believe that 10 bar static pressure is recommended, but 9 bar suits my taste and the crema looks good and has tiger striping – but I am more driven by the taste.

      I must say the TS is my favourite coffee machine (I have had Gaggia Classic, Rancilio Silvia, and a couple of Vibiemmie Domobars – all purchased as Spares or Repair). The looks aren’t the best to my eye, but the coffee is excellent.


  2. Geoff says:

    I already have a portafilter with pressure gauge – just over 12 bar on mine!

    I’ll disconnect over the weekend and have a go. Thanks for the pointers.

  3. Geoff says:

    Got it set to 10 bar now. Very useful reading all the bits you’ve written.

    • admin says:

      Hi Geoff,

      Something I tried today made an amazing difference to the amount of crema and more importantly the taste. I filled the portafilter as normal, the “stirred” the grounds in small circles with a cocktail stick, before tamping as normal.

      The extraction was far better (more dark stripes in the extraction) and the crema was about 20mm on top of the coffee. The bubbles were moving downwards just like a good pint of Guinness.

      The flavour was the best ! (and I don’t normally drink straight espresso). Worth a try as it was a dramatic improvement for no effort.

      I love the TS for everything apart from the looks (and the rust) !

  4. Sam says:


    Thanks so much, you are very helpful and i hope to be enjoying coffee from my TS soon!

  5. Ada says:

    Hi Steve
    My TS is suddenly stop to work can you help me with tip what can cause problem.
    Before couple of days i am noticed to my pump is little silent than normally ( i am thinks finally is everything ok ) but after day or two i am make espresso and after that i am make flush, just to check pump, but after a sec or two in flushing i am got only steam, trying to fix this i am noticed to pump does not can’t drag water from water tank. I thinks my pump is somehow stuck but i am not sure, then i would like to hear your opinion.
    By the way searching for help from local service man he is ask me how looks Ulka pump.
    Any help is welcome THX

    • admin says:

      I think I understand that when you run water through the portafilter to flush before making a shot, you are getting some hot water flow, then steam.

      Poor pump flow could be the problem.

      Check this by repeating the test, but when the boiler is cold. You can then confirm the water flow is correct, without being distracted by the steam.

      Most likely the problem is the pump. Model is ULKA EP5 or EX5, both are correct.


  6. Ada says:

    Yes no water flow, but now when i turn ON TS pump works for 1 min or more with normal sond then stop to work , but when i am check hose in water tank i don’t see water in hose, pump can’t suck water from reservoir ( hose is ok tested ) i really don’t know what can cause this problem except pump.
    What you thinks can Parker coil cause this problem because for me looks similar to your post “No Water Flow”?
    Thanks 4 your time

    • admin says:

      Have you check this:

      Each time the pump operates when you pull a shot, the coil is energised on the solenoid, and a metal slug inside moves to reroute the water flow. You should hear the coil click and if you hold an insulated screwdriver to the side of the coil you should feel a slight buzz of the magnetic field changing. These two effects are quite distinctive, so if they are not present, the solenoid is probably not working.

  7. Ada says:

    I can’t pull a shot anymore because i can’t fill the boiler with water, process is stuck in boiler filling, pump does not getting water then pump works for minutes or two after that i must turn off machine because pump sounds very strange.

  8. Ada says:

    Ok i am order pump.
    Thanks again and all the best in New Year.

  9. Ada says:

    Changing the pump i am fixed low or no water flow at group head.
    Thanks for your time & help Steve.

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