Odd hot water issue to one tap

[DominicO'Regan]

Hi All,

We have a strange situation where one tap in the house, has great pressure, but no hot water unless the hot water timer is on. Everywhere else we have hot water until the tank runs out, but not in the kitchen.

We don't have a combi-boiler, and the pressure is great, any possible/probable causes?

Many thanks.

 

[FiremanT]

You mean that with timer OFF, hot water comes out of all taps but the sink one runs cold? or does it stop all together?

 

[DominicO'Regan]

Yes, with the timer OFF, the kitchen runs warm (not hot), while every other tap runs hot.

 

[JohnD]

I suspect a booster pump.

 

[jeff the gasman]

I suspect cross flow at a shower mixer.

 

[DominicO'Regan]

If its cross flow at a mixer, then I guess I try to isolate mixers then test? Or is there an easy way to tell?

 

[jeff the gasman]

If you can access the pipework you can detect temperature difference and change. Someone else operating the tap.

 

[DominicO'Regan]

Thanks.
We'll investigate further. Incidentally, I noticed the issue wasn't present this morning, so it may come and go. To the layman that does sound like it could be a failing valve somewhere.

 

[jeff the gasman]

Yes.