Air into closed system CH?

[pinheadplanet]

Is there any way air can be getting into a closed CH system?

I'd fitted a new PRV, X800'd the system and flushed it a few times, X100'd it and refilled it to 1.3bar and vented the all rads. Run it a few times and vented the rads again and filled it back to 1.3bar.

After a few days the pressure had gone up a couple of points. Re-bled the highest rad to find more air in it. 'Ok' I thought 'lets see what happens' .

Took some more air out of this same rad again today rather surprisingly.

In the past couple of days the boiler/pipes have started to be a bit noisy again (like vibration noise) whereas it was completely quiet after I did all the work.

Any ideas?

 

[moggridgeplumbing]

Next time you bleed a radiator see if the air smells of eggs or if you purt a match to it it pops. If so then it is not air getting into the system but hydrogen building up.

 

[pinheadplanet]

That's OK is it - Hydrogen?

 

[moggridgeplumbing]

Hydrogen is a by product of corrosion in the heating system. To stop the corrosion and hydrogen build up add a corrosion inhibitor.

 

[plumbswe]

Could just be air in the system left in there from the original fill up. You could have missed venting it out the first time.

 

[pinheadplanet]

I put a lighter to it and I think it did pop, now what?

I did add a litre of Sentinel X100 inhibitor when i refilled the system 10 days ago. Should I add more? (8 rads (three bed semi)

 

[moggridgeplumbing]

I put a lighter to it and I think it did pop, now what?

I did add a litre of Sentinel X100 inhibitor when i refilled the system 10 days ago. Should I add more? (8 rads (three bed semi)

No that's enough. Just let it circulate and do it's stuff. You may need to bleed some rads for a little while yet, but it will stop. Patience is a virtue!

 

[pinheadplanet]

Patience - isn't that those people in hospital

Thanks

 

[pinheadplanet]

LOL It's definately hydrogen, I set light to it as I bled the rad and burnt the heck out of my thumb trying to close the bleed valve

At least I know for sure now.