Bath Shower mixer tap temp problem

[eddyesi]

hoping someone may have some ideas

Recently fitted a new bath shower mixer tap to replace the old cheap one. Ever since the new tap doesn't mix well, runs fine with either hot or cold on full, but when you mix for the shower the temperature constantly fluctuates hot and cold, like the water isn't mixing properly, and seems slightly worse when using the shower rather than straight out the tap Water system is a combi boiler and mains cold, both seemingly working fine

Original mixer was a standard cheap one like this

new one is this one

Thinking
1) New tap is a poor design, the T junction meant the water is fighting and not mixing correctly
2) new tap is faulty, or something is blocked a little, or i managed to fit them incorrectly
3) backpressure from the tap is causing the boiler to work differently

anybody had anything like this, or got any ideas, as i don't want to have to remove all the taps again, they were a bugger to fit the first time, so hoping its somat easy, but probably not

any help greatly appreciated

 

[seco services]

is the boiler constantly running or cutting in/out when this happens ?

 

[eddyesi]

Thanks,

boiler seems fine, sounds like its running constant, no noise or change in lights, so pretty sure its not cutting out.

 

[Technotim]

You do have a strange problem I have had a look at these taps before they are from plumbworld if I remember they are rated at 0.5bar which you would have, I am wondering if you slow down the hot cold supplies to the bsm will it then stabilize if it does then I think you might be using all the flow that the boiler can provide and you cannot rely on the combi to deliver the stable temperature at that max flow.

So the answer would be to fit flow restrictors to the outlet of the shower and in the end of the bath spout.

Let us know how you get on