Central Heating/Combi boiler

[dumbboy]

Help !!!!
Woke up this morn and found that I had no heating or hot water.I managed to reset the boiler,it had overheated.
I now have lot of noise coming from the boiler,it sounds as though I have air in the system.I have bled it several times and air does come out but after starting the system the noise comes back after about a minute.When the banging comes the pressure in the system does seem to wobble (Local pressure gauge).I keep bleeding the system and sometimes there is air and sometimes not! There are 2 red "Accumulators" in the back of the boiler,not sure what these are but they do have air valves on them,the same as a typical car tyre.What pressure should these be at and what are they ???
The boiler is a vaillant vcw sine tw3
HELP me please .....its driving me mad !!!

[stuelwell]

hope you havent vented the "2 red accumilators" these are actually pressure vessels that are factory set. there is normally an automatic air vent inside the boiler that will vent itself. it sounds like either a vave under the boiler is closed off (flow or return valve) or the thermostat on the heating has failed. please seek profesional help, because it could cost a lot of money if you start messing with parts you dont fully understand

[dumbboy]

I havn't touched the pressure vessels and as for the flow and return valves there open.The auto air vent is working as i've checked that.
I've tried to get proffesional help but unfortunatley everyone is booked up till after crimbo !!!
maybe the thermostat then !
Thanks

[dumbboy]

After ringing around and not being able to get a specialist to fix it till the new year I had a look myself.It turned out to be the heating pump.It was fouled up with bits causing a low flow through the heater matrix which in turn caused the water to turn to steam inside it !!!
Cleaned the pump and put it back together and now I have a lovley quiet boiler again !!!!!!!!

[daffidazey]

Wanna come do mine dumbboy? Lol! Mine is up the creek and I haven't clue where to start! Got someone coming to fix it on 4th Jan. x

[gucciman]

well done, was going to answer that the water was boiling inside the heat exchanger and was probably due to low water flow, either due t the pump or the eat exchanger itself being blocked, that or there was not enough water in the system. you've done well fixing it, i would have just put a replacement pump or heat exchanger in.