boiler problem.

[ash65]

could anyone please advise me .i have a halstead combi and the problem
i am having is
1)on occasions when i turn the hot water on it doesn't always work 1st time
i turn the tap off and then on again and then it works
2)when i have the ch on and then i run hot water it knocks the ch off while the hot water is running and when finished,running the water the heating comes back on.

 

[BOB D.O.L.E]

could anyone please advise me .i have a halstead combi and the problem
i am having is
1)on occasions when i turn the hot water on it doesn't always work 1st time
i turn the tap off and then on again and then it works
2)when i have the ch on and then i run hot water it knocks the ch off while the hot water is running and when finished,running the water the heating comes back on.

1) could be the microswitch
2) this is what it should do

 

[spacethegas]

my guess is that the diverter diaphragm is on its way out.

if the hw gradually gets worse thats your penguin.