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suspected air lock on gravity fed cold water system

Postby chris_on_tour2002 » Sun Nov 18, 2007 10:44 pm

good old air locks again, trawled through the postings and cant find a specific related topic so here goes....

recently drained down the cold water tank so i could change the bathroom taps in our new house (no isolator valves, old plumbing) refilled the tank and have good pressure in basin cold tap but no longer in the bath or toilet cistern, just a trickle from the cold bath tap and nothing from the basin in the ensuite where there was good pressure before. is the most likely problem an airlock?

i believe that the correct tactic is to connect a hose to the main and put it in the outlet in the cold water tank to try to push the air out. there are 4 outlets in the tank, presumably feeding different systems which would explain why i have good pressure in some taps and not in others. so my questions are:

1) is the hose/main technique the correct technique?
2) is there any way to find out which outlet is feeding the airlocked pipework?
3) should i have the taps open during the procedure so the air can get out, or closed so the pressure can build?


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Postby peter the plumber » Mon Nov 19, 2007 9:06 am

This doesn’t sound like an air lock to me, more likely to a faulty gate valve or isolator.

It could be dirt or muck in the tank washing down and blocking the pipes when you drain down.

The hose/main technique the correct technique is the right way to fix an air lock, leave the taps open.
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Postby bobplum » Mon Nov 19, 2007 9:35 pm

hi i was intially going to say are they high pressure system taps but that wouldny make any difference to the toilet
id go along with peter the plumber and suspect its muck or air
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