Y-plan heating problem.. Please help me!!!

[chrisscott3689]

hi guys..

i've got a problem with my Y-plan system.. central heating and hot water both working fine from the programmer and the room stat..
when i have the hot water on alone it is fastly moving up the expansion pipe and filling the tank in the loft causing it to overflow..
i've fitted a new cylinder stat as i thought this might be the problem but theres been no change!

any ideas anyone?????

also this is a Y-plan system that has an aerator, could this be the problem or a part of it?

THANKS, chris

 

[namsag]

Partial blockage somewhere and it is not uncommon for air seps to be choca even right down to pump valve

 

[chrisscott3689]

so would it perhaps be best to do away with the aerator then????