Hot tap in bathroom hot at first then goes cold when fully opened

[Samantha123]

Hello

Ive just moved into a new flat & have noticed the hot water tap in the bathroom is fine at first but turn's cold when I open it up fully, all the other hot water taps are fine.

I'm a bit worried there might be a problem with the boiler & could get quite expensive.

Does anyone have any ideas what could be wrong?

Thanks for any help

Samantha

 

[dontknowitall]

It sounds as if the cold and the hot supplies are unbalanced. For example the cold is being fed by the mains at say 3bar and the hot is being fed by the cistern in the loft at say 2 bar. So when the cold is turned on the cold pushes the hot out of the way. (If you have a combi boiler) this can happen too.

Probably best to have a plumber look at it and give you an idea.

 

[tony diggs 69]

Have a look under the basin there could be a tmv fitted ( t shaped valve) if so this could be unbalanced and is inexpensive to sort

 

[Plumbstar Tom]

are you on a combi?

 

[Samantha123]

Hi Plumb star tom, yes I am

 

[Plumbstar Tom]

if you open the tap slightly does it stay hot? ie after 1 min or 2 min its still hot?

If so then the tap is creating too much flow for the combi, either live with it, as the previous householders have or change the tap, or fit a flow limiter to the inlet to the tap

 

[WaterTight]

or turn down the iso if there is one until it still gets hot on full