Hi,

I'm having problems with the hot water in my shower, the tap and boiler were installed approximately 6 months ago and they were working fine until January, when for some reason if I turn the knob to hot water it stays hot for about 20 secs and then it goes cold but goes hot after 50 secs and back to cold etc... Sometimes it is just cold all the time; the rest of the taps are working OK.

I called the boiler company helpline and they suggested that I bought the wrong tap but were not very helpful.

The boiler is an Alpha CD25C and is about 6 months old, the tap is a Neostrahlnd and it has got a sigle lever , the shower only works when there is enough pressure, which we have only with hot water at the moment. I didn't find the Neostrahlnd website so I don't know much about the tap. By the way I installed the tap myself :(

Thank you

Sounds like your mixing valve cartridge is defective... most likely you will need to replace the mixing valve cartridge.

Seems like you will need to go back to place you purchased the "tap" (shower valve?) and get info. On how to get repair parts and how to remove the parts.

Give some of the other guys a chance to chime in though... lots of good ideas come out of this place... maybe someone will have better idea.

Good luck.