air lock

[kevplumb]

evening chaps had to go to a job today air lock in gravity hot water line

history
existing system gloworm ultimate boiler gravity hw pumped ch
been told by customer original boiler in same place but floor standing
didnt do the swap so cant tell exactly what was changed

app every 3 mths the hw side airlocks

usually undo top union and vent
this time wouldnt have it so pulled the stat probe waited for the gurgle

success apparently the system has only started playing up since the boiler was changed

any ideas lads im baffled

 

[ChrisR]

Doesn't the vent go off the HW primary? Perhaps it should!

 

[kevplumb]

yes thought of all the obvious chris plenty of water sufficient head etc its just a head buster

only other thing that crossed my mind the pump is in the return ie neg pressure
poss pulling in thro valve glands
just cant fig why only hw side affected
usually just fills the next rad with air