Pipe sizing for Prima 50

[jelboy]

Hi all

Pott Prima 50 has 22mm flow and return for about 1.5 m to 3 port then the heating flow comes out of it and immediately reduces to 15mm... Is this ok? If the boiler runs at full heat it bangs like a b**tard!

Any ideas

Jelboy

 

[gazthepottertonengineer]

how long has it been in like this ???
Has the problem only just started

 

[jelboy]

Its an older system (boiler 7 yrs old). I have recently changed the 3 port (honeywell) and the programmer to try to fix another prob... HW in cylinder not getting hot when both CH and HW are on... Am stiffled and can't work out best plan of action. There is also a small hall rad which looks like it is acting as the bypass (15mm pipe off HW return runs to it). Poss probs are all related?

Any ides would be appreciated

 

[gazthepottertonengineer]

problem could be down to sludge in system what was the water like when you drained it out to replace 3 port

 

[jelboy]

clear as a bell... any other thoughts please?

 

[Agile]

If its always done this the best fix is probably to fit an auto bypass across the flow and return after the pump but before the valve.

Tony

 

[jelboy]

As I said in a previous post I believe that the small hall rad is acting as the bypass and no it has not always happened...