Gaggia TS – Cleaning the Boiler Level Probe

The Gaggia TS uses a level probe in the water boiler to detect the water level by measuring the conductivity of the water.

The probe is connected to the controller, and there is also a connection to the base of the boiler to form a complete circuit through the boiler and water when the level rises to contact the probe.

If water is not detected by the controller as being in contact with probe, it does not allow the boiler element to switch on.

Over time, scale can build up on the probe, effectively insulating it.  In this case, the boiler level may be incorrect (as the water can rise until it is in contact with part of the probe which does not have scale formed on it yet).  Over time the level of water will rise in the boiler, and there will be less space for steam.

In the worst case, the water level will not be detected by the controller, and to prevent overfilling, it will stop the fill pump and close the fill solenoid.  In this case, the element will not switch on.  Note a faulty element, pressurstat, or controller, can also give these symptoms.

To clean the element, remove the orange wire and loosen the smaller lock-nut.  The probe can then be withdrawn.

Soak the probe in a small amount of descaler to remove any accumulated calcium carbonate build up.

Re-insert the cleaned probe back through the white insulator and tighten the locknut.

Replace the lid and switch the machine on.  Check for steam leaks from the probe area once the boiler is up to pressure.  If necessary, switch off and depressurise the boiler (by opening the steam tap) and tighten the probe securing nut.

The following video shows the correct operation of the water level probe.

 

 

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29 Responses to Gaggia TS – Cleaning the Boiler Level Probe

  1. Tony Hoskins says:

    I’ve spent a several weeks exploring the internet for Gaggia TS users who really understand them and I’ve arrived here. I hope that’s ok. I have been given one of these machines which is 10 years old and hasn’t worked for 4 years. It looks brilliant. The boiler fills ok but heats up only occasionally and won’t get up tp temperature. It did once when testing and I was able to test the steam, water and group functions and they work, but then it cooled down. There is a minor leak on the water supply at the boiler to the water tap which is easily fixed. However today I noticed that the red cable which goes into the centre of the element is loose and the ceramic surround is crumbly/broken. The other two cable terminals on the element are secure. Could this be the reason before I work my way around the other components and the controller? Many thanks for all your videos and blog postings, they are really excellent. The wiring diagrammes at the element seem different on my older model. I hope you can help. With many thanks. I’m quite practical but I’m not sure I’m up for dismantling the relay on the controller, but no never know, I’ll do that I need to.

    • admin says:

      Hi Tony,

      The cable that goes to the centre of the element, isn’t that the overheat thermostat sensor?

      I would think that either the relay (the fault I had) or the pressurestat would be at fault.

      You would need a multimeter to check between neutral, and the two connections on the presseurstat with the boiler cold (not a problem !).

      No volts on either connection – controller relay fault. Volts only on one side of pressurstat – pressurstat fault. Volts on both sides – element fault.

      We normally have controllers and pressurstats in stock (but no elements).

      Good luck.

      Steve.

      • Tony Hoskins says:

        Steve, thank you so much for such clear instructions. The fault is definitely the controller. I’d come to the same conclusion and your diagnosis method confirmed it. In fact when testing for volts between nuetral and the pressure stat, I had volts on both pressure stat terminals as the bolier started to heat from cold. After a short while I watched the voltage on both terminals fall to zero confirming Relay fault. I’m going to place an order for a new controller rather than replacing the capacitor and temperature Relay. Most interesting that I’ve experienced the same fault as you. I’ll add a post once I’ve tested it on receipt.
        Many thanks again,
        Tony.

  2. chris says:

    hi Steve
    I recently purchased a Gaggia TS in working order, having replaced the group seal and shower plate to fix a leak, i now find that the pressure gauge drops after one usage or just drops for no reason at all. If you switch machine off for a length of time and switch it back on then the pressure builds again. Any idea as to what fault may be. Many thanks chris

    • admin says:

      There are two examples you give:

      1. The gauge drops after on usage – do you mean the gauge reads 1 bar say, then you make a shot, and the gauge falls. Or, is it when you draw steam, it falls?

      2. The gauge drops for no reason – how quickly does it fall (seconds, minutes?). Will it increase back to 1 bar by itself, or do you have to cycle the power?

      Steve.

      • chris says:

        Hi Steve

        Thanks for getting back in touch so quickly.

        1. The pressure is fine when making a shot, it is only after using the steam that the pressure drops and doesnt build back up.

        2. As for the falling gauge, you can watch the pressure fall away so it takes just seconds and not recover any pressure at all till you switch it off for a wee while.

        Thanks again Steve

        chris

        • admin says:

          Strangely enough, I think I occasionally have the same fault on my machine.

          When I switch on first thing in the morning, I let the machine warm up for half an hour or so.

          The pressure reaches 1bar, and happily stays around that point over the whole time.

          I then make a shot.

          The gauge reads 1bar, and then I purge the steam wand. The pressure immediately falls to nearly zero, and the element switches on and the boiler starts to heat up until a pressure of 1 bar is reached again. It then functions normally all day.

          My thinking was, how could the pressure gauge show 1bar, and then drop to zero with next to no steam being issued? The steam wand, pressure gauge, pressure switch and anti-vac valve share the same connection to the boiler, and I think limescale is blocking the connection. The element also sings when the boiler is heating up. So for me the next stage is a long overdue descale.

          In both our cases, as the pressure is falling away over only a few seconds, we can eliminate an electrical cause for the moment.

          Have you descaled yours?

  3. chris says:

    After making a latte today, the machine built pressure back up after steam so thought all was ok, held pressure for 10 mins or so, but notice it is starting to slowly creep back down, taking minutes this time to loose pressure.

    • admin says:

      If the pressure is falling slowly over minutes, that would be sort of normal. After reaching 1bar, the pressurestat will open, turning off the element.

      The boiler will cool over several minutes (more quickly if the machine has only recently been switched on).

      When the pressure falls to say 0.5 bar (may be a different figure), the pressurestat closes and the element heats the boiler back to reach 1 bar.

      The cycle should continue.

      Steve.

      • chris says:

        Hi Steve

        The pressure is now at zero and nothing has happened or reheating. I took the boiler level sensor out to check for limescale and it was as clean as a whistle, not a mark on it, our water is very good up this neck of the woods, so not sure limescale is the problem

        • chris says:

          After switching machine off for about 5-10 mins, i switched back on and pressure built back up nicely as though nothing was amiss, made a treble shot latte, shots all working well, no drop in pressure but as soon as you turn on the steam wand the pressure drops which youd expect, but doesnt build back up and continues to slowly drop to zero, when you have to go through the whole procedure again. I have only had machine for a week is it worth returning machine off people i bought it off even if it was a bargain as i only paid £230 for it or what is the next step towards repair? Thanks again Steve

          chris

  4. admin says:

    To clear the fault, I would do the following in order:

    1. Descale

    2. Diagnose whether the pressurstat or the controller is at fault.

    3. Replace the pressurstat (£20) or Controller (£62).

    The problem devalues the machine by about £100, so I would talk to the seller about a reduction.

    Steve.

    • chris says:

      Thanks Steve

      Your advice has been invaluable

      Finally how do i test the pressurstat and controller to find out which one is at fault.

      Many thanks again

      chris

      • admin says:

        You would need a multimeter to check between neutral, and the two connections on the presseurstat with the boiler cold.

        No volts on either connection – controller relay fault. Volts only on one side of pressurstat – pressurstat fault. Volts on both sides – element fault.

        We normally have controllers and pressurstats in stock (but not elements).

        Good luck.

        Steve.

        • chris says:

          Hi Steve

          I downloaded and printed your parts manual… many thanks for that. Could you tell me the part number the pressurstat is and also the controllers part numbers. When i do find the fault i will be in touch to order the parts. Thanks again, sorry for being such a pain lol

          chris

          • chris says:

            Hi Steve, What is the name of your shop and contact details as i would like to order a pressurstat for my Gaggia TS. I was speaking to an repair engineer from Edinburgh and he seemed to think the problem was in the heating element. So today i switched machine on and paid close attention to its behaviour. After making several shots and using steam wand a few times and pressure building back up nicely the machine made a kind of burring noise like it makes when first switched on, and then pressure slowly dropped from unit until reaching zero and failing to build back up. Does this sound like an element problem or a pressurstat problem? Many thanks chris

          • admin says:

            When you draw steam, the boiler may need topping up (if the probe in the boiler is no longer covered). In this case, the pump will run for 5 seconds or so.

            The most likely failure points are the contacts in the pressurstat or the relay in the controller. I would really doubt it is the element. In fact, as you can semi-fix the problem by turning off the power and then back on again, I would put money on the relay in the controller. Of course the controller is expensive, so you would want to be sure.

            Measuring the voltage on either side of the pressurstat with reference to neutral when the fault is present will tell you the real cause.

            You can see the parts here:

            http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=400611261720&ssPageName=STRK:MESE:IT

            http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=400529834854&ssPageName=STRK:MESE:IT

            If you want to buy direct, I can do free P&P.

            Steve.

  5. chris says:

    hi Steve

    i just been on ebay and ordered a new controller and hopefully this will solve my problems
    Thanks again for your sound advice its very much appreciated and i know the first person i will be coming to if i need further parts

    thanks again

    chris

  6. chris says:

    Thanks Steve Received your controller in post yesterday. Just finished changing it over and about to plug back in. Fingers crossed this has fixed my pressure dropping problem
    cheers again for all your help and support. great job your doing helping us novices

    chris

  7. chris says:

    Hi Steve

    Its now been over a week since changing controller and machine has worked perfectly ever since, never missing a beat, nopressure dropping or failing to built pressure back up to its set pressure. So many many thanks again for your help advice and controller from your ebayshop, also checked out limini coffee website, and what a great find that is, not only many many different types to choose from, also gives you a description and advice on each bean and blend AND prices are very competative. What is your preffered bean for latte?

    thanks again chris

    • admin says:

      Hi Chris,

      Glad that cured the problem. Sadly, the controllers are expensive (for what they are – I’m and electronic engineer, so I know what they should really cost).

      I have two favourites from Limini – The Brazilian beans, and a new favourite – El Savador. Both are rich chocolaty types for my Cappuccini.

      Steve.

  8. chris says:

    Hi Steve

    Although controller is a wee bit expensive…it is a small price to pay to get machine working and delivering delicious lattes…lol
    I ordered about 12 different blends of beans from Limini just to try the range and see what i prefer. Would highly recommend them although i did have to pay quite a wee bit extra for delivery, even though it says free delivery on orders over £50. My order totalled over the £100 but still had delivery charge because of my location. But still more than happy to use them again.
    Backflushed the machine last week, should have seen the colour of the foam and water that it pulled through, dont think the previous owners did any cleaning or maintenance on machine at all.

    Thanks again for all your help

    chris

  9. chris says:

    Hi Steve

    One last piece of advice please

    I currently have a DeLonghi grinder, but was wondering how fine you grind the beans? Also if it would be better with a commercial grinder that you fill your portafilter direct? And is there any need for a dear dampner or just the cheap plastic one i got with it?
    Thanks again

    chris

    • admin says:

      Hi Chris,

      The grind of the beans is difficult to explain.

      It is a powder, finer than table salt, but nowhere near icing sugar.

      In the portafilter, it should “just” be possible to pinch it upwards and leave a peak.

      When tamped, it should be possible to turn over the portafilter and the puck not fall out.

      Most coffee enthusiasts would say you need to spend as much on your grinder as the coffee machine itself. A burr grinder is essential to get the best of of coffee, and you should be able to get one on ebay secondhand for about 75-100 GBP. The teeth will grind about 2500kg of coffee before needing replacement.

      A tamper with a flat base and a good bit of weight is a very good investment. The plastic ones are only just passable. You should be able to obtain a good one for 15 – 20 pounds.

      Given the superb quality of home ground coffee which is possible, it is worth obtaining the best equipment you can afford. I was forced to buy four coffees at Starbucks at the weekend, and it cost me the best part of 20 quid, so you don’t need to avoid many of those to get a good grinder or tamper.

      Steve.

  10. Darren Howell says:

    Hi.

    Great to find this place…getting reliable info on the Gaggia TS has proved a little difficult.

    I’ve had my machine for about 10 years with a couple of problems during that time but basically its been very good. Recently the water level indicator has been randomly faulty – indicating no water when there is water in the tank.

    At first I cleaned the probes (? – the metal strips that sit inside the tank) and that worked briefly. This weekend I followed the instructions above and that worked until today. Can you suggest anything else I can do?

    Thanks.

    Darren

  11. Pete says:

    Hi Steve,
    having a pressurestat issue on a Gaggia TE. The ‘deadband’ range is quite large – the pressure cycles from 0.8 bar to 1.4 bar, so a range of about 0.6 bar. This is quite a lot, and is more than the manufacturer’s datasheet quotes.
    I’ve taken the pressurestat apart and can’t see any obvious issue, so will probably just replace – is this a part you have? If so how much is it? It’s a Sirai P302-6.

    Cheers,

    Pete

    • admin says:

      Hello Pete,

      The differential pressure for the Sirai should be about 0.15 bar.

      We should have them in stock in about 3 weeks.

      The price is 34.50 GBP inc UK shipping.

      Steve.

      • Pete says:

        Hi Steve,

        have you got a pressurestat in stock now? If so I’d like to get one in before Xmas if possible – drop me an email and we can sort out payment.

        Cheers,

        Pete

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