hot water everywhere, but in the top floor shower

Greetings Devotees of DIY

I have a rather strange situation, the top floor shower (third floor) has cold water coming out when it should be hot. I can do a temp fix by running the cold water taps in the bathroom downstairs, and after 20 min so it will start to run hot. Strangely the basin in same bathroom has no problem nor is there any problems anywhere else. The other observation is that the cold water seems to be running at very high pressure.

Any ideas how could I sort this........

regards

do you know how the shower is fed ?
it could be that cold water from mains is pushing the hot water back up the tank

It could also be that you have a leaking thermostatic shower or one that always allows some cold through and this is defeating the lesser pressure of the hot supply?

Tony

Thank you both for responding so quickly.

I need to check if its leaking and how's its fed but if its the cold water supply pushing the hot water how ( can I ?) can fix it ?

cheers

If the hot water is tank-fed and the cold is straight from the main, then as you get closer to the tank (ie. higher up in the house) the pressure difference will get greater. As has been suggested, the probability is that the pressure of the cold water entering the shower valve is overcoming the (much lower) pressure of the hot supply. Turning on a cold tap elsewhere reduces the cold water pressure at the shower valve and then you get some hot.

If it's always been like this, you need a pressure-balancing valve which attaches to both supply pipes just before the shower valve.

If it's suddenly started happening then the thermostat in the valve (if it's that type) could have stuck or gone faulty. (Either way, there should be check valves built into the shower valve so that even if you can only get cold water out of it, at least you will not be pushing cold water back down the hot.)

Are you sure you're not so close to the cold tank that the hot water presure is close to zero?......