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Discuss Trevi boost poor flow and not hot enough in the Bathrooms, Showers and Wetrooms area at

  1. Fenlodge

    Fenlodge Guest

    I am trying to fix my trevi boost shower which is approximately 10 years old. Last year i had the same problem with very poor flow and no hot water so I replaced the expensive boost cartridge with a brand new one. Almost exactly a year later the old problem has returned. Thinking it couldn't possibly be the boost cartridge again I have replaced the shower head with the Trevi L7103aa but now there is only hot water when the shower head is held really low and there is still no pressure. I am sure it is plumbed in correctly as in the 8 years prior to this it had always worked perfectly. Would replacing the hot and cold cartridges and gear wheels make a difference or is it time to replace the whole thing ??
  2. Gray0689

    Gray0689 Trusted Plumber GSR

    Could be your hot water to hot for cartridge do you have a thermostatic mixing valve on hot water side
    Cartridges not as good as they used to be
  3. Gray0689

    Gray0689 Trusted Plumber GSR

    Sounds like its time to change it
  4. ecowarm

    ecowarm Guest

    The shower head needs to be the trevi boost one, no other will do. Check for debris on the filter of the cartidge. Check for kinks in the shower hose. Only replace parts for genuine Trevi Boost parts.
  5. Clanger

    Clanger Active Member

    The trevi-boost is a great shower and gets over problems such as negative head, but I have had problems with fixing them. Done everything from changing immersion stats because the hot water temperature is critical, to replacing the pressure reducing valve.

    Had ones that I have failed to fix, because the parts were stacking up and I still hadn't made a difference.

    I think the internal venturi must become blocked or corroded, because the block is made from brass. I live in soft water area where water reacts electrolytically with the brass to produce zinc salts which form in solid mounds to create blockages. Similar problems might come in temp hard areas, but from limescale.

    Never had problems with new units, but the ones a few years old can be tricky.
  6. Karenleach

    Karenleach New Member

    Hi - I'm a complete novice, so have little to add, but the same problem and a potential tiny solution - I replaced our cartridge (not working when we bought the house) two years ago when our plumber refused in disgust to deal with the shower as he found it too difficult. It has just stopped working again already.

    Trevi are quite useful if you phone them (Ideal Standard). they told me to check a whole number of things inc 15mm cold water pipes (yes, most of them are 22mm) and hot water head. I checked and both those things were 'wrong' - the hot water head was not low (3m 40, when boost is designed for a very low hwh), and the cold pipes were 22mm. When I called Trevi back to ask them more qus, they said neither of these things would cause the cartridge to stop working. I was astonished. I said why has it faield in two years then? and he said he had no idea, maybe it was limescale. But we're in a no-scale area. Long and short of it is I am going to try giving the cartridge a good clean tonight, just in case there's some debris in it, and then - he said "try working the springs before you put it back. If they move then it shoudl be OK". If that fails then I'm going to call them again and give them a bit of flak until they give me a clearer idea of what mgiht have caused it to fail. Price is now over £200. Can't pay that every two years!

    I last googled this problem two years ago and got no replies. Now there are a good few questions on the forums about it. Not sure if this means that it;s all parrt of increasing size of the internet, or that Trevi's manufacturing processes have got worse..
  7. ecowarm

    ecowarm Guest

    Welcome to the forum, I would say that as your trevi boost has not been installed correctly you will have no look "giving them some flak"
    They are good and reliable showers when installed and set up as per the instructions.
    I would get a plumber to check the installation and have it fitted correctly, and you may not need a trevi "boost" if you have enough head for a standard shower. IMO
  8. Fenlodge

    Fenlodge Guest

    Thanks so much for your help. We have now replaced the Boost cartridge and touch wood it seems to be working OK. Problem is this used to be our house but we now let it so we just get complaints from the tenants and we haven't actually tried showering in it. We also replaced the hot and cold cartridges and shower hose first but that made little difference it was only with the new boost cartridge that it improved.I thought this was supposed to last 10 years + but there is a family of 6 using the shower non stop and they never use the bath so perhaps it does have a limited life. Just hope this cartridge lasts longer than a year ! if it helps i purchased the boost cartridge from mytub for £154 but still a lot for a spare part. Thanks again
  9. Karenleach

    Karenleach New Member

    Ha ha, Thank you for the welcome and that little piece of advice. As I said, our plumber flatly refused to deal with it and other recommended plumber was clearly busy with easier jobs, so I have been following Trevi's instructions and checking the factors I know how to check. You see, if they flatly tell me that the things I have identified as wrong about the installation "will not damage the valve" which was working fine before (twice) but then ceased to work with no change in circumstances, then I think flak is quite appropriate to give them until they can tell me what may have caused the venturi to fail (twice in about five years). If they can tell me that one or more factor of its wrong installation has caused it to fail, then a) fine, previous homeowner's fault, not theirs. and b) that is useful information that I can present to a plumber that will help me to know what I am dealing with and what my options are.

    If they continue to tell me that the (expensive) cartridge should not be affected by the factors of wrong installation, then I think I deserve to know why I should continue to buy an expensive product that only lasts two years.

    Logical, isn;t it?
  10. Karenleach

    Karenleach New Member

    Fenlodge - Thanks for the purchase tip - and hope you have more luck with your new cartridge than I did with mine.
  11. ecowarm

    ecowarm Guest

    I have fitted a lot of boost showers and have had no call backs and we are in a hard water area.
  12. Clanger

    Clanger Active Member

    I think this might be a soft water characteristic, as I have had several call-outs on these showers in my area.

    To throw some more light on this, soft water affects brass. The soft water acts as an electrolyte, through which electrical corrosion occurs between the copper and zinc, contained in the brass alloy.

    Trev-boost showers are particularly useful in flat installations where there are combination (fortic) type hot water cylinders, usually electrically heated, on economy seven.

    Now most economy seven cylinders I go to, have immersions low-down set at 65 degrees centigrade - which means the water near the top of the cylinder is often 75-85 degrees.

    Not only does this higher temperature affect the operation of the valve - it accelerates electrolytic corrosion in brass. High temperatures contribute to de-zincification of brass.

    The zinc salts leached from the alloy, are enough to block a venturi - hence why water sections on boilers allow this venturi to be removed for cleaning.

    With areas that have temporary hard water - the limescale will be deposited at the heat source and by the time the water gets to the valve, it will probably not create lime-scale deposits to a degree which would cause the valve to fail.

    Permanently hard water areas are ok, because limescale is not deposited from this type of water.
  13. Karenleach

    Karenleach New Member

    Clanger - thanks hugely for this, really helpful insight. I don't suppose you have any thoughts on whether - if this is the problem, which does seem quite likely - there is any way of fixing the valve and stopping it happening again? From what you say, perehaps turning the hw temp down a bit might help, but if the damage is done...

    I assume the damage is not visible on the outside of the valve?

    It might also be useful conversation for me to initiate with the guy at Trevi I spoke to before... and if I find anything useful out I'll post it here.
  14. Karenleach

    Karenleach New Member

    Hi again Clanger and all

    I took the cartridge out and there are definite signs of some sort of corrosion process that may well be what you describe - soft whiteish deposit with a greenish tinge on the filter screens and inside the cartridge. I rinsed and rubbed all the gunk off (as far as I can reach - there will be more further inside the cartridge) and reassembled. It's working fractionally better now, though not back to its proper operating standard. We have a hot water tank rather than combi. If Clanger has any tips on the temperature we (and people like us) should set the hot water at to avoid the same thing happening again (if that's possible), that would be very useful. Given it looks as if we never needed a Trevi boost in the first place (our hot water pressure being high) I am coming to the conclusion we ought to get a different shower rather than getting a THIRD boost cartridge in four years, but for others with Trevi Boosts in soft water areas I'm sure it would be useful to know the outcome of this.

    I'll be calling Ideal Standard (Trevi) again on 3rd Jan when they reopen to ask if they are aware of a soft water electrolysing problem and will report back then.

  15. Karenleach

    Karenleach New Member

    Hi again all

    I rang Ideal Standard and they had not heard anything about an electrolysing problem and sounded sceptical: he said there was no zinc in the brass alloy (puzzled by this as brass is a copper-zinc alloy to my knowledge, though aware you can get dezincificationj resistant brass and maybe that's what he meant). He said the deposit was probably limescale and advised me to soak it in descaler (was surprrised by this as Birmingham is very soft water, and we had also tried this with the previous trevi boost cartridge and it didn;'t work then but he said you can still get limescale problems...). He did imply, though, that they are aware there's a fairly random failure rate with trevi boosts - I think his words were "it might not work - we know there's a problem".
    Personally if I was going to buy another boost cartridge I'd want to know a lot more about this, and I;m still curious about whether the anecdotal evidence is correct that they fail more on soft water areas than in hard.

    But luckily, when I did soak it in descaler overnight (and then, after taking it out, worked the springs a bit to make sure they were working properly), and then reinstalled it, it started working again. So my own problem is at least temporarily solved.

  16. Clanger

    Clanger Active Member

    Hi Karen

    Good work on the inquiry and on fixing it for now. If the valve is zinc treated brass, then its unlikely to corrode in soft water, so my reasoning may be flawed here - and it wouldn't be the first time - but I am willing to theorise and be open to new ideas.

    It may be worth looking at the operating instructions to learn more about the sensitivity of the valve to hot water tempertures and how these correspond with the cold mains pressure required, to give optimum performance.

    The water regs state that water should not be stored at less than 60 and distributed at a temperature of not less than 55 degrees c - but there is a note in the regs R18.2 that while higher temperatures limit micro-biological growth, there is a risk of scalding.

    Accurately setting the temperature of hot water, via a thermostat on an immersion heater, in the bottom of a 1.75m high storage cylinder, which is heated from economy seven over night, is a perilous task. The thermostats are not accurate, and if set at 60 near the bottom, it results in 80 at the top - so an electronic temperature device is needed and trial and error - expect call backs, when customer says 'too hot', 'too cold' and you have to wait another 24 hours to test under working conditions.

    Its this sort of event that makes working on the trevi difficult, because it is sensitive to the balance between hot water head, hot water temperature, and cold water pressure - perhaps check you have these in order again.

    Good luck!
    Last edited by a moderator: Apr 3, 2017
  17. Karenleach

    Karenleach New Member

    Thanks v much Clanger. I think accurately gauging the temp in the cylinder is beyond my skill set but will definitely look at the booklet for getting the right balance between the hw head, temp anf cold w pressure again to try to reduce any further problems. Many thanks for your help and hopefully this thread might have a couple of tips for others experiencing Trevi problems now.
  18. crimsonelf

    crimsonelf Guest

    I have the same problem with a Trevi Boost. It has worked faultlessly for the last 10 years but now the temperature has dropped with the same symptoms already described in this thread. We have soft water via a water softener which we've had for about 15 years so I doubt soft water is the issue. I'm going to try the simplest thing first and flush/ clean / descale everything before shelling out for spares. I'll let you know how I get on.
  19. biggazdixon

    biggazdixon Guest

    Hi Everyone,
    Can I ask what descaler you used Karen as i think I'm going to try the same thing as I'm in a hard water area. Although from what I've read above the lime scale will form in the tank rather than in the cartridge but I think it's worth a go before spending out on a new one.
  20. Karenleach

    Karenleach New Member

    I just used whatever normal descaler I found in the local shop to be honest and followed the instructions on the bottle - I don't think it should make a lot of difference. Hope you can fix yours. Remember the thing they told me about 'working the springs' with your fingers before putting it back.
  21. biggazdixon

    biggazdixon Guest

    I've now soaked the cartridge in Viakal, it says 5 minuntes for heavy crustations so I think an hour or so is all I'm going to venture, it's stopped bubbling anyway so I assume it's done it's thing. The handle end has a sprung centre which seems to be fine but the other end has a visible spring with a small amount of movement, maybe 3 or 4 millimeters. Does sound the same as yours?
  22. biggazdixon

    biggazdixon Guest

    *encrustations! Not large shellfish!
    • Like Like x 1
  23. eileen

    eileen Guest

    Hello Trevi Boosters

    I too have given up trying to get a local plumber to fix it. So I am trying to clean it but have got to the bit in the instructions where it says remove the cold water cartidge by unscrewing anti clockwise and I am stuck. I can't work out how to unscrew it. Do I twist the cone screw in the middle of the cartridge or do I have to get some kind of spanner or similar that goes around the hexagonal outside of the cartridge and unscrew that?

    Sorry if this sounds dumb but I am not a plumber.
  24. biggazdixon

    biggazdixon Guest

    Hi Eileen,
    Yes it's the hexagonal part on the outside of the cartridge, the whole thing comes out of the main body.
  25. Begemot

    Begemot Guest

    I've got a Trevi boost. It recently stopped giving hot water when the shower head was raised above head height. I live in a hard water area & have a Fortic boiler. Removing the boost valve & soaking overnight in descaler has worked, saving about £200. Thanks everyone for your comments & suggestions.
  26. biggazdixon

    biggazdixon Guest

    I tried that but to no avail so I took the plunge and bought a new cartridge. The water's piping hot now and I have a happy family!
  27. Hill Down

    Hill Down Guest

    I am a new member, joined today to get the "low down" on plumbing problems before I spend money.

    I live at the bottom of a hill hence my user name.

    And this was the reason I had a Trevi Boost shower fitted 10 or more years ago.

    The guy who agreed to do the job subcontracted it & it was fitted incorrectly - even I could see that.

    Like a fool I paid him but reverted to using the taps to feed the shower head.

    Must have spen a £1000 before reverting to the original setup!

    It would be nice to have a proper shower without resorting to a "power shower".

    Is it worth having another or should I try another product?

    This is a hard water area.

    And the cold water mains enters at - sorry cant recall but its way over the minimum specified.

    Hill Down / Bill
    Last edited by a moderator: Jul 8, 2013
  28. Wheetman

    Wheetman Guest

    Right, from the off I'll declare that I am not a plumber and you are free to take my advice or ignore it as you choose.

    I have had a Trevi Boost for a number of years and after about 14 months of use I started experiencing the same problems many have reported on here. My plumber was useless. Trevi were more helpful but couldn't understand the problem. In the end I fixed it myself. This is what you need to do:

    1) Before proceeding, order and wait delivery of a new set of O Rings and Screens.
    [TABLE="width: 100%"]
    [TD="class: border"]A963069NU[/TD]
    [TD="class: border"]Trevi O'rings and screen[/TD]
    [TD="class: border, align: right"]£8.32[/TD]
    [TD="class: border, align: right"]1[/TD]
    [TD="class: border, align: right"]£8.32[/TD]
    2) Remove the Boost unit from the shower.

    3) Remove old O Rings and screens and discard.

    4) Now is the time to descale. I use Kilrock industrial stregnth gel.

    5) Support the boost unit in the upright position with the spring facing upwards. (I mount mine into the neck of a jug that has a small spout but anything that will keep it upright will do.)

    6) Using the brush that comes with the gel start feeding the gel into the spaces around the end of the boost underneath where the screens were seated.

    7) Push down with the handle of a wooden spoon or similar on the rod supported by the spring. This will open the valve a little and let some of the gel seep under the valve.

    8) Leave for no less than 5 hours. Yes, that's right, 5 hours. If the gel seeps out top it up a little as you go.

    9) After 5 Hours lay the boost unit in a bowl or other recepticle and add some warm, not boiling, water to completely submerge the unit. The gel will mix with the water and clean any surface scale. Leave for about 15 minutes. Rinse under cold water and dry off. Have a prod of the rod and make sure it returns to be seated squarely in place.

    10) Lubricate the O Rings with a bit of silicon grease that comes with them and replace the O rings and screens.

    11) I grease the screw threads on the base of the boost unit before returning to the shower unit. DO NOT GREASE THE SHOWER UNIT THREADS!! I tried this once and nearly sliced my finger off on the sharp edges of the brass.

    12) Screw home the unit onto the shower and replace taps and cover following the instructions in the manual.

    13) It's a good idea to descale the shower head and the pipe and check the pipe washers at the same time.

    14) Job done.

    I do my unit about once a year like this as I live in a very hard water area and this has worked for me every time.

    Another tip is never to turn on the shower with the temperature setting turned too hot. Sometimes, when the cold water is running out towards the end of the shower, you turn it up to hot to get the last bit of hot water out of the tank and then forget to turn it down again when you get out.

    When you next use the shower the thermostat in the boost unit gets a rush of scalding hot water from the outset and begins to close the hot valve down so you are not scalded. I have found that It can take a long time for the valve to open again even if I pass cold water through it. This will prevent enough hot water flowing through to give you a decent shower. Always make sure that the temperature knob is set to about midway when first starting the shower and increase the hot water as required.

    WARNING: Be aware that the descaling gel will run down the boost unit and whatever you have it supported in. Please ensure that you do this where it will not harm whatever is below it. I tend to leave mine in the kitchen sink overnight. Always read the warnings on the tub. Kilrock is heavy duty stuff and should be treated with care.

    I don't know why it takes a minimum of 5 hours but it does.
    Kettle/iron descalers have not worked for me in the past.

    Good luck and happy showers.
  29. Nick Flack

    Nick Flack New Member

    I am not a plumber however I just wanted to share my experience with our Trevi Boost shower. I also have had the shower for 8 to 10 years and have been very pleased with the performance and think the concept is excellent. A while ago we also noticed that the flow rate and temperature had was dropped. Having taken the unit to bits, checked the non return valves for debris and air locks, couldn't see and signs of what might have caused the problem. I considered a new valve however before spending around £200 I checked various forums for clues as to what might be the reason. I came across one suggestion that I replace the rubber O rings and gauze after leaving the boost cartridge completely submerged and upside down in descaler. (A jam jar is perfect). I carried out this and was amazed at the result. The shower is back to new, delivering a good flow of super hot water and cost just under £15 in total for the O rings/gauze kit from the net and descaler from the local DIY store. I hope this helps others in my position and potentially will save a great deal of money purchasing not required valves.
    • Like Like x 1
  30. turnpin

    turnpin Trusted Plumber

    Hi Nick and welcome to the forums...thanks for your valuable info no doubt will prove to help others who use these forums....regards Turnpin:)
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