I'm probably asking for trouble with this question, but here goes....

I had tenants complaining of a luke warm shower and discovered that their boiler hot water temperature was set to about 50º.

The shower has a thermostatic valve and has no separate power control. As expected the mix was coming out about 38º. The manual says that at least +10º is required in the hot supply and that they recommend 60º. (Meaning that for a 43º shower they'll need at least 53º at the boiler, but higher in reality to get some power).

However, the bathroom sink has separate cold and hot taps (no mixer) which means they are at risk of scalding themselves. This is why they turned the boiler down.

Is there a way - without fitting an electric shower and without replacing the bathroom taps - to have the shower temperature up as required, but keep the wash basin safe?

Aside: Previously I had a thermostatic valve with a power handle, but tenants turned it up full blast and then complained it was cold. I figured prioritising the temperature was a better route as long as the power was acceptable.

  • 1
    To anyone asking why I don't just fit an electric shower, or install a mixer tap at the sink: It's a period property with traditional fittings and I want to keep it that way. I've also just spent about 400 quid getting the new shower installed.
    – Tim
    Feb 3, 2021 at 12:44
  • Is an "electric shower" one that has an electric, on-demand heater to provide some additional heat as needed? Otherwise, I'm thinking "electric" and "shower" don't belong in the same sentence...
    – FreeMan
    Feb 3, 2021 at 12:50
  • Yes. I mean boiler stays at 50 or whatever and electric shower heats water. I thought this was a common term. Googling it, it seems it is.
    – Tim
    Feb 3, 2021 at 12:56
  • 2
    @freeman Fair enough. I always forget on here to mention UK. Models with pump for extra pressure also known as power showers over here.
    – Tim
    Feb 3, 2021 at 14:02
  • 1
    In case I need to justify by concerns regarding danger and survival (which I don't). I have tenants. Tenants complain at best. Sue at worst. I'm a good landlord and their grievances seem reasonable. In my own home I constantly pull my hands away from the kitchen tap when I forget it's at 60º but I have nobody to complain to, so I say "ouch" and get on with my day.
    – Tim
    Feb 4, 2021 at 10:16

1 Answer 1


You can install a standalone tempering valve on the line to the sink, or (probably a larger one) on the line to "everything but the shower" which would protect the kitchen sink as well, for instance.

  • Thanks for the suggestion. The kitchen has a mixer at least. Adding just to the basin supply should do it.
    – Tim
    Feb 3, 2021 at 13:58
  • I'm going to accept this answer before trying it. It's the only response so far that actually addresses the question I asked. I wasn't aware of such a gadget and now I am. Thanks
    – Tim
    Feb 4, 2021 at 10:19

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