binding taps with mega flow

[harrypotterton]

i have 4 sets of ceramic disc mixer taps, running on a mains system with a unvented hot water store 3 of the taps are binding i have al ready changed the catridge/ceramic dics on 2 pairs 6 months ago now they are starting to bind again.any ideas? it s not a .scale problem

 

[simond]

If it is a Poxi Batterton Megaflo then it is entirely possible that the internal air bubble has partially gone, leading to much higher static pressures during periods of no water drawoff.

If so, recharge the airgap and ponder what makes a Megaflo better than other unventeds. Their advertising.

 

[harrypotterton]

thanks for your in put
its not a bubble top . i dont think its a pressure problem either as bove the cold and hot draw offs are after the ressure reducing valve

 

[simond]

Your tap problem may not be a pressure problem - although I think it is very likely. But your PRV location has no relevence to my suggestion, all unvented have the PRV before the outlets.

If the airgap fails one of two things will happen;

- a safety valve will eventually open at around 6 bar
- failing this, something will rip open to let the water out

 

[harrypotterton]

Thanks again but i m sure this is not a pressure issue.the hot and cold out let is relifent to the posistion of the pressure reducing valve as this reduces down to 3.5 bar .The standing pressure before the valve is only 3.5 with a working pressure of between 1.5 to 2.5
The taps them self have a max rating of 10 bar.

 

[simond]

To be pedantic Harry, for the second time the position of your PRV and its rating are neither here nor there if the airgap fails.

When you heat water it expands - where does it go? The word 'unvented' is a good clue I'd like you to consider.

 

[harrypotterton]

have checked the expansion vessel which is charged at 6bar and there is nothing to suggest that the safety valves have opened.