Hot on mixer tap not working

[Mattk]

We recently moved into a house which has a mixer tap in the kitchen. The first few days it worked fine but since then when you turn it to hot it starts to run warm/hot and then goes back to cold and never returns to hot.

All other hot taps in the house are of the standard type and are fine in that they run hot and stay hot.

Due to this it sounds like a problem with the mixer tap rather than the supply.

Does this sound feasible?

[The Builder]

I guess the tap has one lever. Yes it's possibly the tap. Perhaps it's a cartridge type, and this has got faulty.
It's possibly not a supply problem since the tap worked for a few days.
Take the tap apart and have a look :o)

[AlBags]

You could have a situation where the cold is coming on and pushing up the hot pipe which is also open in the mixer. This happens with one of my customers sink mixers.
Check it by isolation the cold (if it has an isolation valve) or switch off cold feeds. Then try the hot alone again.