Mixer Shower Issue - how to isolate

hedgewitchery

Hi,

I was on here a few months back, getting some help with my broken toilet flush. I managed to sort that, thanks to the sage advice of the group, and now I'm back with a shower issue. I've got a Mira Element mixer shower which has started running cold/lukewarm. I had a look on here and on the Mira website and tried taking off the shower head and hose, to no avail, so I suspect it's the cartridge that needs replaced? I watched a video about it and it seems like it might be relatively straightforward to take it apart to see what it looks like so I can buy a replacement, but they said that you had to isolate the water supply to the shower first and I'm not quite sure how to do that, given that all the gubbins for the shower is behind a wall. The shower is on a tray/plinth thing that I might be able to remove, but I don't want to get gouging if that's a red herring. Should I just attempt to turn off the whole water supply to the house? If I do that, should I turn off my central heating boiler first? Sorry if these are stupid questions...

Or should I just bite the bullet and get a man in (in which case it will probably have to wait until I get paid!).

Thanks in advance for any wise words!

ETA - sorry, I should possibly have said the hot water is running fine to the sink right next to the shower and to the other shower in the house, so I don't think there's any problem with the boiler or pipes or anything.

mi-key

Yes, isolate the supply generally means just turn off the house mains at the stopcock unless the pipe to the shower has a seperate valve. Turn off the stopcock and run the taps for a bit until no more water comes out.

No need to turn your boiler off if its a combi. 

RedFraggle

Had a similar problem and it was limescale so you may just need to soak the cartridge in vinegar and pop it back. There was no isolation on ours either so we had to go off at the stopcock . 

hedgewitchery

Thanks, both. I don't live in a particularly hard water area so I think it's unlikely to be limescale, but guess there's no harm in trying before ordering a new one. I think I can turn the water off where it comes in, but I've never had to do it before. Had a lot of cooking and washing to do today, though, so it wasn't the time to start experimenting!

molerat

There should be separate stop valves to the hot and cold supplies to the shower, mine are in the attic above where the pipes go down in the wall.

hedgewitchery

molerat said:

There should be separate stop valves to the hot and cold supplies to the shower, mine are in the attic above where the pipes go down in the wall.

That's a helpful thought, thanks, but unfortunately my attic is fairly inaccessible, so it's probably easier to just work out how to turn the water off (as I should probably be aware in general anyway). Good to know for the future, though!

hedgewitchery

Grrr, finally got round to turning the water off and dismantling the shower, only to find that it's not a Mk 2 Mira Element, where I could have prised out the cartridge with a screwdriver, but a Mk 1, which apparently means I need to buy one of these things:

https://www.showerdoc.com/mira-o-key-spare-1063671

It means I can take out the filters and give them a clean as well, though, so I guess probably worth a punt.

It also means a replacement cartridge is £150, instead of £70  Glad I didn't just order one on spec!

hedgewitchery

hedgewitchery said:

Grrr, finally got round to turning the water off and dismantling the shower, only to find that it's not a Mk 2 Mira Element, where I could have prised out the cartridge with a screwdriver, but a Mk 1, which apparently means I need to buy one of these things:

https://www.showerdoc.com/mira-o-key-spare-1063671

It means I can take out the filters and give them a clean as well, though, so I guess probably worth a punt.

It also means a replacement cartridge is £150, instead of £70  Glad I didn't just order one on spec!

So the weird plastic gizmo turned up and I managed to dismantle the various bits and clean them/soak them in vinegar. It didn't make any difference, though, so I've bitten the bullet and ordered a replacement cartridge. I'm slightly concerned I'm throwing good money after bad if it's something more fundamental that's broken, but a new one would be at least £350 without fitting (I'm assuming I'd have to go for a very similar model or then have lots of knock-on issues with having to drill new holes and make the wall good, etc), so it's worth a punt. Medium to long term, I might get rid of this en-suite altogether, so it's probably worth just nursing it along for now. I also have the same model in my main bathroom, so might even be able to reuse it.

Sorry, boring update, but at least I now know how to isolate it, take it apart, and put it back together again!

hedgewitchery

Well, in the next thrilling installment that nobody was waiting for, I've fixed it. I ordered a new cartridge and swapped it out... and it made absolutely bu88er all difference. I was stumped for a bit but, long story short, I think what has happened is that the external water pressure has somehow increased and the shower can no longer balance the hot and cold properly, resulting in it never getting above lukewarm. So, I bought some of these flow restrictor thingies:

https://www.amazon.co.uk/dp/B0BFHQN4S7?psc=1&ref=ppx_yo2ov_dt_b_product_details

And it's now, if anything, too hot (although that's probably partly because I was fiddling with the internal regulator thing as well - I may turn that back down again, but I'm so sick of taking it apart and putting it back together again, I might just put up with not turning it up as much for a while).

ThisIsWeird

Gripping stuff!

What type of boiler/DHW system do you have? Any increase in incoming water pressure/flow should remain balanced for a shower, so it doesn't really add up afaIcs.

hedgewitchery

I'll admit I'm speculating wildly and possibly wrongly about the root cause, but I'm just extrapolating from what has worked. I'll give a rundown on events, though, in case anyone has any alternative suggestions/interpretations. Warning: this is very long and boring!

I have two identical showers, both of which have historically been very powerful and hot. They also just have one lever for both on/off and temperature, no separate flow and temperature controls. Just after Christmas, the one in the guest room refused to get above lukewarm no matter what you set it to and, while the main one I normally use wasn't obviously malfunctioning, it was definitely not getting as hot as it was previously - I'd subconsciously put it down to it just "feeling" cooler because of the cold weather etc, but tbh hadn't really noticed until the other one went wrong.

I tried removing the shower head and hose and the water coming from the unit was still lukewarm, so I discounted any issue with those. That was when I tried cleaning the filters and swapping the cartridge, etc, none of which made any difference.

Separately, my boss suggested that maybe I should try turning the stop c*** down, in case it had somehow been turned on more strongly or something. I was half hoping this would help - because I did want it fixed, obviously, but also half not, as I was going to be raging if the fix was as simple as that, lol! That also didn't do anything, however. Having run into a brick wall, I almost resorted to getting a plumber out, but to be honest I couldn't see what he was going to be able to try that I hadn't done, except recommend replacing the shower, which I didn't want to do. So I went back to the manual to see if there were any other bits and pieces that might be going wrong. At that point, I noticed that there was an option to fit a flow regulator for high pressure systems - aha, I thought! Maybe one was fitted and it's gone wrong and needs replacing. At this point I did what I probably should have thought to do earlier: I took the hose and shower head off the main shower and put it on the guest one... and the water ran hot. Words cannot describe my emotions at that moment after wrestling with this psychological puzzle for weeks, lol. One slight snag, however - I looked at both hoses and neither of them had a regulator fitted! But, my main shower had a different head on it. One of these to be precise:

https://www.amazon.co.uk/gp/product/B075L3STT2/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

(please, no need for lectures as to whether these do anything or not, that's a different story).

The hoses were identical, so it looked like the showerhead was making the difference. Just to test the hypothesis, I of course tried the guest shower head and hose on the main shower and - you guessed it - lukewarm. So, by a process of elimination, I could only assume that the restriction caused by the shower head was reducing the water pressure enough to allow the shower to get hot. This was also borne out by the fact that I'd noticed that earlier on, even with the malfunctioning bits in place, the water would briefly get hot before settling back down to lukewarm, so it wasn't that hot water wasn't being produced and getting to the shower at all, something was actually throttling it back. So then, as a final test/solution, I bought some of those little regulators in my previous post and that has caused the shower to work again with the original hose and head.

Also, and this is also highly speculative, of course, I coincidentally happened to be looking at a planning application in on my street and one of the comments talked about there having been water pressure issues recently, with complaints being made to the water suppliers, so it's not completely unlikely that there may have been recent work done recently that may account for an increase in pressure, although I've never noticed any issues with it personally.

Anyway, to answer your question as best I can I've got a Glow Worm 30cx combi boiler, with separate central heating and hot water. No tanks or anything like that. The hot water is set to 62 and the water in the taps has always been very hot throughout, so I didn't really think it could be the boiler that was an issue, although I did investigate but couldn't seem to turn it up any higher anyway. And, like I say, since I've fitted the regulator, the water is, if anything, too hot at the highest shower setting.