Intermittent working Vaillant boiler?
Is the flue obstructed?
Open the cover +check the pump is working on setting 1 or 2, change+ check again,listen to noise?
Do u have a carbon monoxide meter ?
Where U refill the system from the main,is there a leak?
Do U have thermostatic controls on radiators?
Turn heating on ,wait for it to warm up ,then Open up each radiator top plug and wait for the air to clear and hot water to run out ,one by one ,until all the air is out;
starting from the one furthest from the boiler
They may have scaled up!
When U open the hot water tap in the shower for the 1st several minutes does it smell of limescale ,then clear up ?
When did you drain the system?
Do U live in a hard water area?
If the system has not been drained a long time there is sludge in the system,which means turn off the boiler,take doff the plug,turn off mains water,
close all the taps in the house,do not use the flush in the loos until U finish draining ,bleed the sytem until it is drained fully-no water comes out of drain plug! Unsrew and block the connector pipe joints so it does not leak to the carpets, get a 2nd person to help you ,take off the radiators from the wall one by one to the garden and jetwash /hose them,darin water left and put them back if they happen to be modern type ,otherwise buy new ones of same size for each room and replace them.Boiler servicing does not include the draining of the system beware.
My system was leaking slightly from the drain plug;put a new plug and was ok then.
hope this effort helps to solvc your issues
kind regards
Ahmet Hajiahmetoglu, September 2010
