I've switched off the cold feed to the expansion tank and drained down a living room radiator. Then put in the additive. However, I seem to have lots of air in the system which I now cannot get rid of - despite bleeding all rads several times. The rads are cold and the boiler now won't fire up. The pump is activated and I've tried venting it from the screw at the back. I've now twice successfully re-set the boiler but it switches off after about 2 minutes and I have to wait until I can re-set it again. It's a Potterton. Now I have no heating and it's not even firing for hot water. I think I'd rather have had the banging!
Hello again, Andrew.
I've left the vent screw out of the pump and re-set the boiler (a little reddish button underneath). The boiler burned for exactly one minute before tripping again and shutting down. The pump is extremely hot but the pipes leading down from the loft (pump and boiler are in loft) are luke warm only and the rads water is cold - with no air. The pump is running (humming) even when all the system is turned off at the programmer. The expansion tank is still full. I'm wondering if the pump has packed in on me. It's cerainly a bit noisy. Or is that trapped air? However, each time I manage to fire up the boiler, I get more air being released out of the system vent upstand pipe near the pump. It has a hexagonal nut at the top. And, I can't hear the expansion tank filling up after bleeding - it's right up in the loft apex so I can't see inside it.
Yep, will do. Speak tomorrow.
Thanks very much for your help and patience so far.