Help !!...Blocked 15mm pipe behind shower tiling

[maldin]

Hi,
Hot water from mixer unit getting less over approx 1 year. Mixer valve is fully round to max hot.
Isolated pump power supply, disconnected pump discharge and checked flow of cold water OK
Checked flow of hot water from pump discharge OK
Removed mixer guts and checked water at mixer, cold water OK hot water very low almost negligable. The mixer is recessed into the wall and consequently the pipework is also behind the tiles.
It looks as though the pipework to the hot connection on the mixer valve is blocked.
Have I come to the correct conlcusion and how can I clear a blockage in the pipework without having to bust all the tiles and shower in the process?
Any help appreciated
Regards to all forum members
Mal Dinsdale

 

[Tinitus]

First check there might be a filter on the inlet pipe to the shower. I have had this problem several times. Clean the filter and Robert is your mum's brother.....

It is unusual to have a blockage in your hot water pipe. Good luck.

 

[corgigazza]

Try connecting pump outlet to mains water with shower cartridge removed also check for filters in pump and that flow switches on pump are not jammed

 

[ChrisR]

It could of course just be that the shower cartidge is knackered! Yo might be able to run with the cart removed, depending on design, just to check for filter etc blockages.

 

[maldin]

Hi,
There were no filters in the original pump, I have replaced the pump, installed filters and they are all clear the pump works fine as does the flow switch. The problem is between the hot discharge of the pump and the shower mixer unit. The mixer unit is Newline and is recessed into the wall. I have removed all the internal parts from the mixer that are accessable. I'm not sure what you mean by cartridge, there is no cartridge shown on the parts drawing of the mixer. It is possible that there are inline filters installed where the 15mm pipe attaches to the mixer unit but they are inaccessable as the pipework is behind the shower tiles. The shower unit was originally installed by a qualified plumber, so I would not expect him to have installed in-line filters in such an unaccessable location. I have tried forcing normal mains in the reverse direction from the mixer back to the pump, water does come out but again at a very low flow rate.
Any further advice much appreciated otherwise I have to get a plumber to confirm my conclusions and start knocking tiles off the shower wall.
Regards to all
Mal Dinsdale