Ideal Icos HE12 hot water issue

[Gassy_NE]

I have the above boiler with an unvented cylinder. There is no problems with the heating but it kettles when the hot water is on (on it's own) so constantly firing up and knocking off. No fault codes.

I think there must be some sort of circulation issue (possibly in the cylinder coil or that area) that isn't letting the boiler keep the correct flow/return differential temps or it's overheating.

The house is only 9 years old and I've replaced the 2 port valves and pump previously.

Where is the best place to start with this? Is it worth opening the hot water 2 port and blasting some water through it with the filling loop?

Thanks for any suggestions...

 

[king of pipes]

The pump is the heart of the system i would say start there .

 

[Gassy_NE]

If it was the pump then surely it would also affect the heating... probably moreso than the hot water, bearing in mind the central heating gets hotter than the hot water.

 

[king of pipes]

Maybe but pumps do loose performance with age , make sure your programmer is on constant for hotwater turn the cylinder thermost up to say 70degrees c observe the 2port valve can you see the lever move to the middle postion if you move it side to side it should have no resistance on the lever the 2port valve is then open , turn the cylinder stat down to 50 degrees and the valve lever should motor over to one side and have resistance the valve is then closed try that . cheers kop

 

[townfanjon]

Manual gate valve/ bypass clogged up or closed