Air lock in kitchen tap query

[john west]

During some work on our central heating the heating engineer drained the water in the system, to fix a leaking motorised valve. Also during the work he turned off the mains outside water supply valve in the kitchen cupboard.

Everything now works fine, except the kitchen cold water tap sometimes just dribbles for a while when turned on before then going on to work OK.

I phoned the Water Board and spoke to an engineer and they told me to open and close the mains supply valve in the kitchen cupboard four times and then open all the cold water taps fully and run all the water from the taps for ten minutes.

I told them my water in the bathroom sink and bath (and i think also the toilet) upstairs runs off the large water storage Tank in the loft, they said to still open the taps up.

My first question is how could it make any difference if the mains valve in the kitchen is open and closed four times with all the taps closed since this would not enable any movement of water... would it ?

My second question is: i cannot see how opening the taps in the bathroom upstairs would be relevant since these taps are supplied from the water storage tank in the loft, and not the outside mains which is giving the problem to the kitchen sink tap.

And incidentally, all the cold water taps upstairs drained the loft storage tank in the loft empty in the ten minutes and so no more water came out.( I'm hoping that fact will not create any more air locks ).

Grateful for any advice. Thanks.

[Tim+]

Running all your cold taps and cisterns off your cold water tanks is very ?old school? but I?ve never heard of such an old school system that didn?t have direct mains supply to the kitchen tap.

I?d be very unhappy with such a system and would convert the cold supply to mains, or get someone to do it if you?re not sure how. Gravity cold supplies have some advantages (quieter cistern filling, ?reserve? supply in event of mains failure) but will also give poorer maximum flow and mean that you?re routinely drinking stored water. When did you last check your loft tank for dead animals, bugs etc?

It occurs to me another possibility might be a sticking ?jumper? in your kitchen cold tap. When it?s flowing normally, what?s the pressure like? Is it easy to stop with your thumb say or is it too high to do that easily?

I think the water board were just trying to get rid of you.

Tim

[Brian Gaff (Sofa 2)]

I agree with you. The problem is that the air lock could be anywhere between the cold tap and the stop c*ck. Are there any high points in the pipe, ie where it goes up, then down again? Have you got good pressure on mains water? Most mains water supplies around here are strong enough to shove air out in the first couple of minutes of full on running, usually drowning anyone nearby. If the pressure is low, you might have an issue? Are the pipes in the house lead and quite floppy?

Brian

[Brian Reay]

Perhaps the idea is that, as the upstairs taps drain the tank in the loft, the ball valve opens. It is at a high point in the pipe work*. Trapped air tends to migrate to high points**. With the ball valve open, it can escape.

• The ball valve is on the mains pipe work.

** The idea has some merit but depends on the pipe work layout.

You could try fixing a tube/ hose somehow over the tap and sucking with the tap on. You just need to get the system going, not suck it all out ;-)

[John Rumm]

Is this tap directly supplied from the mains cold feed? (it should be, but if in doubt, see if you can stem the flow of water from it by putting your thumb over it - tank fed you probably can...

If the tap was partially seized and not opening fully (or much at all), then winding back and fourth may free it and extend the amount of travel you can get.

It will cause a demand of water to refill the cistern. Just another way of running some water through the cold main.

it ought not unless you have some poorly though out pipe routes. It does tell you that the cold cistern is not refilling quickly enough. This could very well be due to a lack of mains cold flow that is also affecting the tap in the kitchen. Sometimes the mains flow into a property can't match the supply rate from the cold cistern. Sometimes doubling up on the float valves can help, but in other cases only a new larger pipe run from the water main into the property will really fix it. How much of any of that is a problem in real life depends on how much water you need at once.

[Dave Plowman (News)]

Sound like a response read from a script - like when you lose your broadband.