Worcester bosh combi boiler strange pressure problem

[hallowitch]

ive been having problems with my 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 gauge 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

 

[Aquarius]

Firstly, if you can smell gas, turn off at the emergency control valve and call 0800 111 999.

Check your filling loop/key isn’t ppen or passing, this can build up pressure, discharge externally then refill.

 

[hallowitch]

Firstly, if you can smell gas, turn off at the emergency control valve and call 0800 111 999.

Check your filling loop/key isn’t ppen or passing, this can build up pressure, discharge externally then refill.

Firstly, if you can smell gas, turn off at the emergency control valve and call 0800 111 999.

Check your filling loop/key isn’t open or passing, this can build up pressure, discharge externally then refill.

thanks for the reply no gas leak just a wee smell of gas in the air for a second as the pressure dropped
boiler is off till Thursday until its looked at by my gas man its interesting you mention the filling loop/key because the plumbers always leave it in and I'm sure ive been told you shouldn't do that (i wont take it out i don't touch the boiler) over the last 18mnts ive had all my rads changed not all at once and Ive got myself totally convinced that the banging has got something to do with the extra rad i had put in the kitchen something to do with it feeding of the main rad (a plumber told its back to front but wouldn't make the boiler bang )and dosnt get very hot its getting taken out

Its got to fixed whatever it is ive asked the gas man to come and check the whole boiler to see if he can find the problem and fix it

again thanks for your reply very much appreciated this boiler it driving me mad