Combi Diverter valve only working from one tap?

[Jackuzi]

Hi all,
We have been having problems with our water going hot then cold then hot in cycles of about 2 minutes which makes a fun shower experience. I have called in a plumber and when checking he found that the diverter valve piston was only fully engaging for the tap that is situated right next to the boiler. When any other tap in the house is operated the piston barely moves. We now have no hot water to any other tap other than the one by the boiler. He said that replacing the diverter valve 'may' fix the problem but it's a gamble. I have no other choice but to get this done to hopefully fix it but any thoughts as to what else it could be if that doesn't work?
Thanks,
Glen

 

[namsag]

Diaphragm within it is starting to wear so changing the divertor should cure it ,cheaper option is to change the diaphragm.

 

[Jackuzi]

Diaphragm within it is starting to wear so changing the divertor should cure it ,cheaper option is to change the diaphragm.

Thanks for the reply Namsag. Desperate for a nice hot bath so I popped out and bought a new garden hose and a hoselock adapter for the tap in the utility. Managed to fill the bath upstairs by going through 2 windows . Can't wait for this to be fixed on Tuesday.

Still had some issues where it the hot stopped pumping, had to turn the kitchen tap on as well to get it running again. What a waste of hot water just to get a bath filled.

Can anyone help me understand how this works? Is it the back pressure/lack of flow forces the valve to close and therefore closes the switch?

 

[Agile]

Its nothing to do with the different taps.

Because of the failing diverter valve the boiler needs a greater flow of water to make it start up.

But you dont need to know why this happens, we do, but all you need to know is that the diverter valve needs to be repaired or replaced.

Tony