Is this a dumb idea?

ComicGeek

breaking_free said:

Thanks ThisIsWeird.

I've cranked the spindle as far as it can go with the knob offski. I reckon it is as you say - the mixer won't allow it to go any hotter. Good to know a leccy shower won't be an improvement as that's one less blind alley to go down.

Both showers were plenty hot over summer but are adversely affected by the cold weather it seems. Money isn't really a problem so if I could achieve a better result by paying someone I'd happily do so. Wondering why other money saver's showers aren't affected like mine?

The maximum temp of the shower shouldn't be affected by winter/summer - it's not like an electric shower where it can only raise the water temperature so much, and therefore the output temperature is limited in the winter when the incoming water comes in much colder. Yours will just mix hot and cold water to get the right output temp.

Have you looked at the temperature of the bathroom, and looked at increasing it? People feel the difference between the room temperature and the water temperature, so lots of people increase the water temperature in winter to get the same feeling of warmth when showering. If your bathroom is cold, then you will feel like the water is colder.

ThisIsWeird

breaking_free said:

Thanks ThisIsWeird.

I've cranked the spindle as far as it can go with the knob offski. I reckon it is as you say - the mixer won't allow it to go any hotter. Good to know a leccy shower won't be an improvement as that's one less blind alley to go down.

Both showers were plenty hot over summer but are adversely affected by the cold weather it seems. Money isn't really a problem so if I could achieve a better result by paying someone I'd happily do so. Wondering why other money saver's showers aren't affected like mine?

It's a bit weird.

Your boiler has two separate controls for CH and DHW temp, and I understand the max DHW temp output is 60oC? And does the display show it as being 60oC? I guess it does, since the pure hot tap in your bathroom is 'ouch'.

It should be as Comic says - pretty much regardless of outdoor temp, the boiler should be able to deliver DHW at ~60oC. Any difference due to the cooler incoming should be slight, and certainly not enough to prevent you from having a shower as dangerously hot as you like. So, yes, there must be a limit to what the thermo cartridge in the mixer allows. Ie, it always has to blend some cold through, since I understand they're also designed to shut off the flow if, say, the cold supply were to fail.

If you had a 'manual' mixer instead, I am pretty sure you could scald yourself all day long if you liked.

Whether a different make of thermo mixer would allow a hotter output temp, I don't know, but suspect that some will, just because you always get some variation. On my old Victorian style thermo mixer, which uses a commonly available cartridge seemingly shared by many makes, I can override the temp using a similar button to yours, and often tweak the temp up in small stages at the end of a shower just for 'fun'. It's 'oooooh - ouch!' for a few seconds until you get used to it, then another tweak and a further exclamation, and so on. I can't imagine that temp of water all through a shower, or even allowing it to come over my head - it's pretty darned hot. As the temp is increased, the overall flow drops off a bit as clearly less cold will be blended with it, but not to a significant degree.

Anyhoo, I wonder if it's worth unscrewing the cartridge on yours and seeing if it can be tweaked further before refitting? I have no idea if they can. Or you can certainly get a manual control mixer with no safety features...

Apodemus

breaking_free said:

I'm pretty sure women like a significantly higher temperature than most men.

Coming back to this point, in light of your new issue of not being able to adjust the shower temp as high as you might like...

In a bid to save a little on the central heating bill, I reduced the thermostat setting on our hot water tank but found that the hot water no longer met my wife's required temperature for a bath.  So I turned it back up and when she next had a bath, I tested the temperature of the water that she was sitting in.  Turned out that her desired water temp was 50C, which was what I had previously turned the tank thermostat down to!  No wonder she could no longer get enough suitably hot water for her bath.  I can't even put my hand in the water at that temp and would consider it dangerously hot!

I've noticed that most thermostatic mixing valves on showers are set at 38C, with a maximum around 46C, so if you are a 50C gal like my wife, you might struggle to get the shower to a temperature that suits.  

ThisIsWeird

F-f-f-f-f-fifty?!!!

Lawdie!

If that's the case with you, BF, then I suspect a manual shower mixer may be needed. Bearing in mind that it will almost certainly have zero protection against flow drop-outs, such as someone flushing a loo. If you are already touching 50oC, then that is gonna be more than unpleasant.

Perhaps worth contacting some of the big shower mixer manufacturers - I dunno, Grohe? Mira? Aqualisa? There's plenty, but bear in mind that similar-looking products will likely have similar or identical cartridges inside them, and ask then what the max output temp can be set to with a 'safe' tweak.

I was also going to suggest a thermo mixer valve such as the kind that limits temps to hot taps, and perhaps having a separate shower handset in your cubicle, but that would be messy, and might not even work.

Fling off emails to the make companies, see what they say?

breaking_free

Thanks Apodemus and ThisIsWeird. Yep, I definitely like my showers hot! Boiler is set to the max of 60c but my thermostatic valves in both showers think they are doing what is best for me and cooling the water down "sigh".

I am thinking a manual mixer is the way to go. Now I'm a fairly confident DIYer but have never faffed around with showers until  now. Where do I begin? Any YouTube vids around that walk through the process of changing a thermostatic bar mixer for a manual one? A recommendation for a good quality manual mixer would be appreciated as well!

EDIT: Watched this vid - looks dead simple to swap the mixer out but what brand replacement would I swap it for?

https://www.youtube.com/watch?v=Qbn_SJi5Sas&ab_channel=POUSEaroundtheHOUSE 

Apodemus

Before you rip everything out...

Someone above mentioned the room temperature, but the height of the shower head also makes a difference.  The water droplets cool significantly in the air before it reaches your body, so the further the stream travels between the shower head and your skin the lower the water temperature.  Can you lower the head at all?  Or change the flow characteristics of the head?

breaking_free

Well yes, I could lower the head as well. I shall have another shower tomorrow (I skipped it today) and see if the adjustments I've made plus lowering the head makes enough difference.

Thanks to everyone that has contributed so far.

Apodemus

ThisIsWeird said:

Perhaps worth contacting some of the big shower mixer manufacturers - I dunno, Grohe? Mira? Aqualisa? There's plenty, but bear in mind that similar-looking products will likely have similar or identical cartridges inside them, and ask then what the max output temp can be set to with a 'safe' tweak.

You can normally find the design characteristics in the specification sheets for each shower mixer (well, at least for the quality manufacturers).  This should include the normal temperature range and the max/min water temps that the mixer valve can handle. 

I remember seeing one where it suggested that the minimum input cold temperature should be 10C - I'm not sure why this should be an issue for a mixing valve, but my input cold water is about 7C this morning and I have seen it as low as 4C.  I guess some valves simply cannot reduce the cold flow-rate sufficiently to deliver 42c water with a 60C hot input and 7C cold.

GDB2222

Have you completely dismantled the thermostat control knob? They normally include a limiter to prevent turning it too far.

Apart from that, it should be easy to replace the entire unit with a simple non thermostat version, if that works better for you. 

A 30kw combi is adequate for most people.

ThisIsWeird

Yes, it's almost certainly the thermo cartridge just working within its design. Not really a surprise as they simply cannot reduce the cold flow below a certain level, as this would presumably be detected as a flow failure, resulting in the shower shutting off.
But, in order, I think I'd try: emailing shower manufacturers - tell them you just need a couple more degrees... Remove your existing cartridge - you've already been half way there - and see if there is any way it can be reset. I dunno, circlip removed, spindle turned, clip replaced. Once you have the design of cartridge, I'm sure there will be decent info out there. Take lots of close-up photos, and you can pop it back in place and continue to use it while we all 'research' it. And 'consider' a manual valve, which could well be a straight fit - the pipe spacings tend to be standard. But I'd caution against this option for the obvious reasons - genuine risk of scalding.
A manual valve would also need to be a diverter type, cos you have two outlets. Can you get to the pipework behind the shower? If so, then fitting a thermo blender to the hot, set at 50oC, should ensure that's the max temp in any event?