Thermostat Mixer Tap not going above 40 degrees

3 Sep 2020
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United Kingdom

New build house (builder has been contacted but if this can be fixed myself I’ll do it)…

On the bath is a bath, hand held shower head mixer tap. Hansgrohe -

Problem I have is we can’t get water out of it above 40 degrees. The taps on the wash hand basin are fine.
No matter how far past the 40 degree ‘lock’ I turn the tap the water just doesn’t get any hotter. The water temperature at the boiler is set to 55 degrees and all other hot taps are fine.

40 degrees is far too tepid for a bath.

I had a look at the instructions but its not clear to me what needs done. I’m happy to wait on the developer getting back to me, but they will be weeks - so if its something quick and easy then I’ll give it a go.

Attached photos of the tap itself and the instructions. Any advice appreciated.


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1&2 remove the knob and other parts as shown
3 - turn water on full and adjust the spindle until the maximum temperature that is required flows, you will need a thermometer.
4 - water off, refit the components as shown, the alignment of the small ring is critical
5 - water on, adjust spindle until the flow temperature is 40
6 - water off, refit knob and other parts so that the indicator is against 40 without moving the spindle.
Thanks flameport.

I’ve followed the instructions which are fairly simple now you’ve given me that guidance. On stage 3 I had to turn the spindle as far as it would go to get water that was remotely ‘hot’. For example, I can hold my hand under the bath tap with the spindle fully turned, but the wash hand basin hot water is too hot to do that.

Is there a chance the actual thermostat works of the mixer tap are just faulty?

I’ve put it all back together and the water is hotter, but still not as hot as the other taps. Literally going to test it with a bath now!
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Thanks Jim - I had suspected that, but the builder tells me thats not the case, I had a look myself and theres nothing to see with the bath panel off. Apparently the scald safety is the tap itself? I’m in the bath now lol and its still nowhere near hot enough. I like when Its so hot you can just barely step in and it stays hot for ages.

Neighbours tell me their identical taps deliver roasting hot bath water when the tap is pushed past the 40 degree limiter.
Doesn’t make any difference Jim thanks.
Thing is the actual tap body itself is ‘burning’ at the hot feed, but the tap is clearly feeding in too much cold water to the mix.

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