Locating the cause of an airlock

[toasterx]

In my son's house, they're frequently finding that the cold water taps (which all run off the cold water tank) get airlocked. I've put together a short length of hose to clear it using the hot supply but it happens so often it would really be useful to find out how it's getting an airlock in the first place ... where do I start?

T

 

[Newboy]

Is the tank filling fast enough to keep pace with demand - when the bath tap is running a full flow does the tank fill as fast/faster than the rate at which water is being drawn.

I assume that the kitchen cold tap is on the mains?
Is the hot water provided by a combi boiler?

 

[toasterx]

I'm not there now but am pretty certain the kitchen sink tap is mains and that the boiler is NOT a combi ...

 

[Newboy]

If the hot water supply is gravity fed (i.e cylinder and cold water cistern/tank) then you cannot clear an airlock using the hot supply - the pressure on both hot cylinder/tank and cold tank feed will be the same.

The kitchen cold tap should be mains fed (if it isn't then stop drinking water from it!). First thing to check is the tank filling & keeping pace with draw off rate.

Using a hose from kitchen cold (assuming mains supply) then you can push the air back into the cold water cistern.

Out of interest, what symptoms are you/your son experiencing and how often?

 

[toasterx]

Hmmm, the hot supply is gravity fed but some sort of air lock seems to clear when I do the above procedure, I run the water for maybe 30s, hear a bit of bubbling and then the cold supply starts running freely again after a short period of stuttering. The root symptom is that the cold taps on the bath and basin in the bathroom, and the cold tank-fed supply to the upstairs toilet cistern just stop running at all. Executing the procedure I describe gets it all going again for a period of hours to days and then it recurs. I did previously clear it once using their hoover but it damn near killed the thing. Running a hose from the mains downstairs is possible but trickier to say the least

 

[HERTS P&D]

Fit a new float valve to the cold water storage tank and take it from there.

Andy

 

[Newboy]

First thing to check is the tank filling & keeping pace with draw off rate.

 

[longdogs]

Can you see any pipes from the water tank that go up then down (like an inverted V) over obstructions or other pipes?

Also, check that the hot supply pipe coming out of the top of the cylinder is at a slight angle to allow air to escape? (Up away from the cylinder- not down)