Min. Hot water supply temp. for shower mixer valve.

[FarmerN]

 

I hope,my DHW is to be heated by GSHP as far as possible,  so I think I want to run at as low a hot water temperature as possible in the cylinder. The plumber suggested today that a lot of shower mixer valves would not work at a low hot water supply  temperature, he said some will not turn the cold off completely within the mixer. Is this true, do I need to chose a mixer carefully ?

It will be surface mounted mixer due to wall thickness. A lot of the time there will only be two of us using water off a 300 litre tank , so thought I would be running it at a temperature in the low 40s. Pushing it up if we had a house full.

I did look online at mixer valves and one cheap one specified a minimum hot supply temperature of 55C . I was horrified !

There will be a sterilisation cycle.

[JohnMo]

I had my UVC running today, supplied by ASHP, and the shower was a lot cooler than previously when supplied via a combi boiler, even though it was turned down to supply at 45.

 

So could be an issue

[Conor]

We've our tank set to 45c.

We've four thermostatic mixers. All work perfectly except one which doesn't go cold. Just very hot to warm. It is a complex concealed unit it just as likely that I didn't put it together quite right rather than an issue with water temp.

 

If you have tank set to 46-48c, won't be an issue.

[Andehh]

Yep, we have this issue in our mixer shower valves.

 

On first use all were cold at maximum temperature, because they're all designed for a hot supply several degrees warmer.

 

I adjusted them on, a crappy fiddly job, and at best could get them 'quite hot' but not much more. This also means at full cold they're still mildly warm.  I do need to have another fiddle.

 

Annoying as we paid a bloody fortunate for them.

 

Our digital aqualisa works fine.

 

 

[FarmerN]

Thanks for replies.

Sounds like a real issue, I'll email a couple of manufacturers and see what response I get.

 

I came to another shower mixer valve ,on line, with a minimum hot supply of 60 deg C!

With an ever increasing proportion of water heated by heat pump , sounds like the shower mixer valve manufacturers need to up their game.

 

Am I nuts even thinking I only want to heat the hot water cylinder to low 40s Deg C ?

 

Like a lot of things in my new build , GSHP, UFH, MVHR, PV, Batteries, triple glazing, I have no experience at all and will only find out what we should have done when we have been living there a while.

Live in a huge old farmhouse now, damp but extremely well ventilated ,no central heating just log fires so a bit of a change coming for retirement.

[FuerteStu]

My guess is that there will be a new line of "compatible" products that are very expensive. 

With other products that would work in their catalogue left cheap but not labelled as compatible for profits sake. 

 

It's a bit like when induction hobs came out and there were expensive lines of pots and pans released designed for them, when often their budget range also worked just as well. 

 

 

[JohnMo]

34 minutes ago, FarmerN said:

Am I nuts even thinking I only want to heat the hot water cylinder to low 40s Deg C ?

40 degs is very low, possibly too low without huge quantities and anything with a mixer will give luke warm water at best.

[Conor]

1 hour ago, FarmerN said:

 

Am I nuts even thinking I only want to heat the hot water cylinder to low 40s Deg C ?

 

45c min. We had our setpoint at 40c. When it got that low it wasnt hot enough for the likes of a bath. Now have it set qr 42c.

[Gone West]

8 hours ago, FarmerN said:

Am I nuts even thinking I only want to heat the hot water cylinder to low 40s Deg C ?

We heated our EASHP powered UVC to 45C and didn't have any problems with our bath thermostatic valve, nor the thermostatic showers.

[FarmerN]

1 hour ago, Gone West said:

We heated our EASHP powered UVC to 45C and didn't have any problems with our bath thermostatic valve, nor the thermostatic showers.

Good to hear.

Could you tell me make and model of shower mixer Please ?

[Gone West]

14 hours ago, FarmerN said:

Good to hear.

Could you tell me make and model of shower mixer Please ?

This was a few years ago, but the make was Nikles and I think the model was Pure Tronico.

[FarmerN]

@PhilT In another thread you posted this.

Quote

 Yes the icon you mention is the dhw temp. 55 is very high. I use 42 but each household has different requirements. 

Please can you tell me what shower tap you use, is it thermostatic?

I'm having very little luck asking manufacturer which valve to use for a low temperature hot supply to shower. The replies I have had so far seem to want a big differential between hot supply and shower delivery temperature.

[JohnMo]

Grohe shower mixers used by me, really need 47/48 degrees for a nice hot shower, 45 and it's getting cooler in the shower. Seem to be getting about 10 deg temperature drop via mixing.