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The group on my machine is running cool/not hot enough

hi nick (roulstone)

as you can probably see there is some issue with my website currently but it will be another hour or two before my web guy comes online

assuming you dont have limescale buildup in the machine, and no leaks, a group that is not reaching normal operating temperature is due to the anti vac valve

unfortunately an anti-vac valve that is sticking doesn't always stick, so the fact that you report that the anti vac valve dropped down on your test does not mean that the anti-vac valve on your machine is functioning reliably. unless you have scaled up the machine, and assuming your thermosiphon circuit is sealed (no leaks) then the anti vac is the only possible cause: remove it then disassemble and descale - it is a very simple device and it is unlikely that it will need to be replaced

you can also test this in the way frans mentioned in his post; turn the machine on and wait for an hour; if the group surface temperature is cooler than it should be (ie. you can keep your hand on it) then open the steam wand a few times and flush a good amount of steam through

you will then find the group warms up to full temperature without the need to touch the group lever i believe

this indicates that the anti-vac valve is not functioning reliably

another way to test it is by locking the steam wand valve in the open position next time you cold start the machine. after a couple of minutes steam will start coming out of the wand; close the steam valve at this point and you will find that the group reaches full operating temperature

there has never been any issue with 'air in the thermosiphon' (indeed the water drains back out of the thermosiphon on the 2012-16 L1 every time you turn it off) and all the dimensions of the LR are identical to the 2012-16 L1 as far as the boiler, heat exchanger, injector, and thermosiphon are concerned - the only difference is that we disconnected the supply pipe from the boiler to the HX and connected a pressurised cold feed pipe to the end of the HX instead

the 2012-16 L1 is vulnerable to flash boiling in the thermosiphon at the group, particularly if the machine has been sitting idle for an extended period of time, which is why we recommended a short flush (around 30-50mL) after the shot was pulled for that machine which completely eliminates the issue

with the LR and L1/2/3 this issue does not arise because the boiler is run at 1.0 bar as the pre-infusion pressure is not provided by the pressure in the boiler

let me know how you get on

hopefully the website will be back in an hour or two

Kind regards

Reiss Gunson
T. +64 20 4056 4412
Londinium Espresso

ps - the website is sorted, but we lost your thread so i have posted this thread to replace it as it isnt worth performing a restore from backup to get it back


  • Many thanks for your rapid replies on this, and apologies for my slow response. I'm working long shifts at present, not much time for coffee. However, I took up Franze's suggestion and left the steam pipe on whilst heating up. Yes, the group got up to normal temperature. So does this confirm that the antivac valve is to blame?
  • exactly right

    back in the day espresso machines were not fitted with anti-vac valves and the requirement was that they be started with the steam wand open, for exactly this reason

    a 17mm wrench/spanner and a 12oz hammer to strike the end of the wrench is all that is needed

    once the valve is off the boiler you can then remove the stainless 'E' clip and the valve will fall apart

    drop all parts to the valve in a strong descale solution until all signs of scale are gone

    rinse thoroughly under the cold tap and reassemble

    when you reassemble the shaft of the valve should easily fall into the down (open) position - if you sense any binding whatsoever if you hold the shaft between forefinger and thumb and slide it up and down something is amiss

    the steam pressure in the boiler needs to be able to easily lift the valve shaft so the o-ring seals against the ptfe bush in the valve, and when the boiler is turned off and the pressure in the boiler ebbs away the weight of the valve shaft should easily be enough to pull the valve fully back down into the open position for the stainless 'E' clip is resting on valve body with no gap under the 'E' clip

    kind regards

  • Thanks reiss, I should have time to do this next week. It's weird though. On my previous machine, a Quickmill Andeja the anti vac valve spewed water, steamed and spat loads of water around before lifting and was very slow to drop down again when the boiler was de pressurised. I was always replacing it, trying to reduce the amount of water prewed on top of the boiler. On the L1 the valves movement is very distinct, clean and sudden, to me it looks great.
  • hi nick

    apologies for the delayed response

    that is the purpose of the test where you started the machine with the steam valve open; the only thing this test achieves is it breaks any vacuum present

    you performed this test and the group reached full operating temperature, therefore a vacuum was present, therefore the anti-vacuum valve is not performing its function.

    if you can't bothered cleaning it just replace it - it isn't an expensive part

    kind regards

  • Again sorry for slow progress on this thread. I finally got around to removing, cleaning and replacing the anti-vac valve on Friday. No change. The group still does not get warm. Venting any amount of steam does not help either. I noticed that the lower thermo syphon pipe is too hot to touch whease the upper pipe hot but touchable, whilst the group itself remains almost at room temperature. The only thing that gets the group to heat up is pulls a small amount of of water through the group. Having done this, it stays warm. The other symptom, (if it is a symptom) is that since lubricating the piston and cylinder, the shots are shorter. The lever is not jumping, its just biting at a higher point.
  • hi nick

    thank you for the additional information

    any chance you could pull the group top and take an image of the seals on the piston please?

    also, whilst you have the group top out turn the machine on, wait for the boiler to pressurise, then check that you have 4 strong jets of water entering the brew chamber when you look down the sleeve from above

    kind regards

  • I took the lever off last night. The machine performed as expected.

    Having put it back together, it worked perfectly this morning, heating up without the need to pull any water through the group. I'm not sure if this is a permanent fix or not. I'll let you know
  • Any chance of an image of the piston seals on the piston?
  • Lifted the piston tonight and shamed into changing the seals. They have been in for approximately 4 years and functioned perfectly in terms of delivering a shot, but maybe they were not sealing the inlet properly?
  • hi nick

    yes, that will be the cause

    if the circuit isnt sealed the thermosiphon will not flow, or at least will not flow at the design speed as there is a pressure loss on the inlet side of the circuit which reduces the pressure differential between the high and low side of the circuit so the thermosiphon flows more slowly than it should

    in most cases it is visible as the seals leak (upwards, out through the hole in the back of the group top, or downwards through the bottom of the group), but in other cases you can have the middle seal leak but the bottom seal does enough to stop water leaking out the bottom of the group

    kind regards

  • Thanks for the the explanation. Looking again at the seals, I could see that they were very flat, but could not see how this would affect the thermosyphon. Not really tested it yet, I was almost guaranteed to work tonight. Tomorrow will be the real test.
  • Happy to report that all is loverly again. The machine heats up reliably, and the grab point is the lowest I can remember.
  • hi nick

    thank you for taking the time to report back - this is what makes the post worth reading for other customers

    kind regards

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