wrote:

This year I got 2 radiators changed (a large one in the lounge and a
small one in the bathroom). Now more air is entering the small bedroom
radiator. The frequancy of the air is un-acceptable, not only making
bubbling noises that wake people up but also requiring to be bled once
a week or every other week.

Did this radiator change require a drain down? If so, was new corrosian
inhibitor added as the system was refilled?

If there is not enough inhibitor in the system then one possiblity is
that they gas you are collecting is not air, but being generated by
corrosian.

What I want to know is 'why' is this air getting in ?

I have not seen any leaks in the system, my plumber says that it's
through the vent and the pipework needs to be changed to 'fully pumped
system'. BUT the question in my mind, is why is this happening? The
pump hasn't changed, so surly the vacumn in the system hasn't changed,

so why whould the water in the vent pipe now be getting sucked lower
for air to get into the system? Also why would this be made worse once
again by 2 new radiators.... it doesn't add up in my mind, any ideas?

The new rads may have changed the flow resistance of the whole circuit...

When I had a (badly designed) vented system it suffered a similar
problem due to the vent being on very close to the suction side of the
pump. Everytime the pump kicked it it would suck in a gob of air via the
vent. I fixed it by cutting into the vent pipe about a foot above the
pump and inserting a tee, then connecting the feed from the header tank
to the tee (blanking off the connection to the other side of the pump
that it used to connect to).


--
Cheers,

John.

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