Can an Excel Shower Cartridge Cause Temperature Fluctuation

Discussion in 'Plumbers' Talk' started by merlot128, Nov 23, 2017.

  1. merlot128

    merlot128 Member

    We have recently been getting erratic shower temperatures and the shower is barely warm enough for a comfortable hot shower. It is one on the newer type Excel cartridges although a few years old now. I have removed the cartridge, cleaned the filters and turned the inner spindle to the maximum temperature setting and it has made no difference. Our boiler is Wooster Bosch Combi Green Star, domestic hot water preset to 55 degrees and cannot be altered, and there is plenty of hot water at the taps.

    The only thing I can think of is that the temperature sensor in the cartridge has gone faulty. The temperature fluctuates and sometime gets hotter when you turn it towards the cold setting. A new cartridge is expensive so I do not want to splash out unless I know that this is the problem.

    Any advice would be appreciated.
    M.
     
  2. nigel willson

    nigel willson Screwfix Select

    Yes it is quite possible but I would expect it to last more than a few years!if I remember rite there are temperature stops on these valves. Have a look on their website to see what I mean
     
  3. KIAB

    KIAB Super Member

    Any temperature fluctuation with other hot taps in house?

    How old is combi.
     
  4. Ask Mira themselves - tell them your symptoms.

    (And it should have a 5 year warranty)

    Your combi has a fixed temp output for DHW? Blimey, how old is it? And I guess it won't, therefore, have a temp gauge that you could monitor?
     
  5. KIAB

    KIAB Super Member

    That's why I like my Vaillant, can adjust HW temperature.:)
     
  6. merlot128

    merlot128 Member

    I have noticed that the boiler pressure has wild fluctuations as well. When I checked it two days ago around 9:00 heating on for about two hours it was down in the red almost at zero, so I topped it back up to 1.5 bar. Yesterday about the same time it was back down in the red, so I topped it up again to 1.75 now worried that we had a leak under the floors. When I checked it at the same time this morning it was up at 3.0 bar and almost in the upper red zone.
    Could this be the cause of our shower problems?
     
  7. Possibly.

    But your pressure loss is likely - hopefully - not a leak as such, but the safety valve opening at 3 bar to release excess pressure.

    You need to have someone in to check your exp vessel and safety release valve.

    (See the 15mm copper pipe that comes from your boiler and goes to the outside? Keep an eye on that for (hot) water coming out - place a container under it.)
     
  8. KIAB

    KIAB Super Member

    How old is boiler.

    And is there a magnetic filter fitted, if not worth while having one fitted, Magnaclean Pro 2 highly recommended.
     
  9. The Teach

    The Teach Screwfix Select

    Mira shower products are very good,so many many times better than the un named lookalike chinese imports that 'flood' the Uk market.

    The boiler hot water temperature needs to be checked with a thermometer for stable temperature for atleast 6 minutes,its a process of elimination.

    Seen many showers with fluctuations,sometimes its normal if the boiler supplies preheated water combined with much colder winter inlet water temperature.

    Iirc,that cartridge has an adjuster for high or low inlet pressure,yours should be on high and the hot&cold should be mains fed.

    Should be fixable :)
     
  10. Regardless of your shower problem, you do have an issue with your boiler pressure that also needs sorting.

    How DIY capable are you? There are many threads on here about checking your exp vessel.
     
  11. merlot128

    merlot128 Member

    >>(See the 15mm copper pipe that comes from your boiler and goes to the outside? Keep an eye on that for (hot) water coming out - place a container under it.)<<
    Definitely has water coming out. British Gas Home Care engineer booked for Monday.

    >>How old is boiler. And is there a magnetic filter fitted, if not worth while having one fitted, Magnaclean Pro 2 highly recommended.>>
    Boiler is about 5 years old, Green Star Junior 28i. A magnetic filter was fitted many years but not sure if it has ever been maintained unless it is included in the annual boiler service by the Home Care engineer.

    How DIY capable are you?

    Quite good I will have a search.
     
  12. KIAB

    KIAB Super Member

    Suggest you have a look at the filter, might need emptying.:)

    Unlikely engineer would have checked it.
     
  13. merlot128

    merlot128 Member

    I will do but, would that affect the DHW temperature? I thought the filter was just to prevent a build up of sludge in the CH system.
     
  14. KIAB

    KIAB Super Member

    The magnet will collect any sludge, but filter still needs emptying once,twice or more times a year, depending how bad the system is.
    It won't affect the HW temperature, as it's on the CH return.
     
  15. If you have an engineer coming out, no need to start investigating it yourself - good chance the safety valve will need replacing at least. The expansion vessel may just need topping up (with air), but may also be faulty. Are you 'covered'?

    A 5-year old boiler is pretty young. If there's any threat of a large bill looming, I'd be looking at Bosch footing some, if not all, of the bill.

    (Check your warranty. But bear in mind that you are also covered under the CRA).

    Have a look on you tube how to open and check the magnetic filter. How much sludge is inside will give you an idea of the state of your system, and what to do about it.
     
    KIAB likes this.
  16. merlot128

    merlot128 Member

    We are covered under the Home Care, although with a £50 excess for each repair, which I had to commit to up front. Instructions for the magnetic filter are on the label so I will leave it until Monday and ask the engineer if they clean the filter as part of the annual service which they are going to do on Monday as well.
     
  17. Do you have the large plastic spanner for the filter?

    I suspect they will not include this as part of the boiler service, even tho' it's a quick and simple task and is pretty important - it can highlight forthcoming issues with your system and allow you to take pre-emptive action.
     
  18. The Teach

    The Teach Screwfix Select

    Some gas boiler service companies just do a very basic gas safety check (as per their internal documents) not a full service but they are willing to do repairs not always at their full cost.

    Buyer beware time.
     
  19. merlot128

    merlot128 Member

    >>Do you have the large plastic spanner for the filter? <<
    I have the spanner and have watched the video so I will do this over the weekend.
     
  20. The Teach

    The Teach Screwfix Select

    Have you a thermometer to check the actual hot water supplied by your boiler,also record the cold inlet temperature and see if your boiler is sufficient to supply a suitable constant shower temperature.

    the mira valve should be set up to provide a safe and constant comfortable temperature as stated in their supplied document (as it would have been done on professional installation).

    These items need setting up but sometimes will work Ok out of the box.
     

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