Worcester bosh combi boiler junior28i problems

[HALLOWITCH]

ive been having problems with my Wooster combi boiler banging at night so ive had all my radiators changed and on Saturday had M C 3+ cleaner through the system and sentinel x100 inhibitor put in the boiler was fine that night
Sunday night about 3 in the morning the boiler banged then i could hear a woosh of water going through the boiler and another bang

this afternoon i heard the boiler fill up so i watched the pressure gage while it was filling it lost pressure into the red usually sits on 1 bar and running rich (smell gas)after it had stopped filling the pressure went back up to 1 didn't hear the pipes bang this afternoon

any ideas help gratefully received
i will be using a plumber or gas safe what ever one i need to do the job and fix the problem

 

[ianmcd]

If it is a greenstar Junior there is a manual vent at the top of the heat exchanger, did they remove the boiler casing when changing the rads ?

 

[HALLOWITCH]

ianmcd thanks for the reply no they didn't the rads have been changed over the last 2 yrs the last one getting done on Saturday
when i changed over the rad in the kitchen about 18mths ago i put in another rad feeding off it this one only gets warm (i hope that makes sense)

 

[ianmcd]

It is possible that you have trapped air in the heat exachanger , cant say for certain though

 

[HALLOWITCH]

i will get that checked out
i cant rember when this banging started but i haven't spent much time at home in last 18 months a week or 2 hear or their up until lockdown

i think the new rad feed may have been put on wrong(back to front maybe) and I'm going to get that sorted this weekend ive turned the boiler off and its not going back till this is sorted
I'm not sure if its the boiler that's banging or the pipes going into it its like the pipe at the bottom bangs then starts filling up it stops filling up then the pipe at the top bangs while its filling it loses pressure after its filled the pressure goes back to normal 1bar