Boiler Popping

[bally74]

I've been trying to get rid of a clicking noise from my pipes recently. This has got worse since installing TRVs (bi-directional), I have rinsed out all the radiators, added inhibitor and drained all the air, no air seems to be getting into the system, the pump is running ok. I have a small bore system but I've gone 15mm on the TRVs also my house-extension is all 15mm, been a pain on balancing but seems ok. I have checked the pipe runs and managed most of the clicking by using pipe lagging but still have some clicking noise from these, thought about fitting plastic but a little close to the boiler but it is a clicking I can live with, However the big noise is a popping deep noise which I can't locate, I figure it must be from the boiler itself. I have noticed that the feed pipe from the F&E tank gets hot from about 2metres from the boiler but the expansion pipe remains cold. I have checked the F&E tank and it seems a bit stagnant and no water flows from the expansion pipe and the tank is very cold. Any help would be appreciated.

 

[chrishutt]

the expansion pipe remains cold

That's the vent pipe, not the expansion pipe (which is the same as the feed pipe). The vent pipe would normally get hot so you need to check the water level in the system. The feed & expansion pipe could be blocked so you need to check what happens in the F&E tank when you drain off a bit of water.

 

[bally74]

Well I should be able to check the F&E pipe soon, tomorrow after work(Wed).
I'm gonna drain the system down and add some inhibitor and X200 noise reducer, hopefully this will clear the problem.
The F&E pipe is only hot from about 1metre from the boiler and the vent pipe is still warm but not as much.
How can I check the level in the vent pipe, should it match the level in the F&E tank and how can I check whether the vent pipe is actually blocked. I suppose I can stick some cable down the end but my attic is cold and dark and I probably wouldn't be able to find out the level of the vent pipe this way.
BTW my boiler is a potterton Netaheat MkIIF, I am also looking for a cover for the bottom of this, looks rather untidy with all the electrics showing.

 

[bally74]

Well I drained the system down, the F&E Pipe wasn't blocked, I also reduced the length of two 22mm pipes from the boiler to relieve the pressure of them being tight around a 90 degree bend.
I re-filled the system and added fernox inhibitor and x200 noise reducer.
Still getting air out the system but it seems quite settled now and most of the clicking has stopped.
I get a quieter pop still but I seem to get a growling noise from the pump now. Maybe cause of the air still, I do have my hot water thermo set to 50' but the hot water is too hot to touch, could this be my problem, do I need another Thermo? The F&E pipe is a lot cooler now, the same as the vent pipe.