Mains airlock, anyone?

[Lindyboo]

Well folks, it’s me again and more water worries (of the house plumbing variety). Getting well fed up now.

Moving sideways from my recent thread on rising damp – very long story since then – but it turned out that the fundamental problem was a leaking mains joint which has been weeping – and then gushing – underground. Ground and walls have been getting a soaking for potentially years hence our flood after the hurricane.
The joint was repaired a week ago and we had an immediate improvement in water pressure as expected. Since then the pressure has gradually fallen away until there’s barely enough to run appliances.

The reduction in pressure after the initial boost began within about 24 hours but for four days after the joint repair the new joint was visible awaiting the hole filling in. The joint was definitely not leaking which suggests something else is amiss. The pipe and new joint are plastic.

There’s no supply issue locally (have checked) and we share a mains with only one other distant neighbour, whose supply is normal.

I’ve arranged for our water authority to come on Thurs to check the mains supply which will tell us if it’s their end or ours, but in the meantime I’m wondering if there’s an airlock in the mains which is causing the problem?

Previous airlocks (other properties) have been obvious by the noise of trapped air and/or spurting taps. There was some minor spurting after the joint repair but none since. In the past I’ve got rid of airlocks by the usual method of attaching a hose from one tap to the other, but as far as I can recall, airlocks are usually found only in either hot or cold supply – not both, as is the case here, which suggests a mains issue.

So, after this long explanation, has anyone had a mains airlock, i.e. affecting hot and cold supply and if so how was it cleared? If I can get it cleared myself it’ll be better than waiting till Thurs for the water bod.

Thanks

 

[88v8]

If an airlock has mains pressure behind it, in my experience it will self-clear.
Do you have an outside tap, does that also lack pressure?

What is the supply pipe made of?
I wonder if it has sprung another leak. After all, if it has been leaking for years, then other parts of the pipe have not recently been exposed to much pressure, with the leak repaired they are/were subject to full pressure, hence another one has given way.

Potentially serious having a leak under the house as it can wash out the foundations.

Flood...claim... if it was partly due to the leak then if they are minded to be difficult, the insurers might argue there was a pre-existing cause/gradual deterioration/no specific 'event' within the meaning of the policy. All a bit of a pain.

Not having much fun right now, are you?

Ivor

PS otoh, after this is fixed, your damp should eventually clear, unlike the problems of various other houses with ground levels etc which may be much more intractable.

 

[Lime]

A reduction in water flow or pressure is unlikely to be caused by an airlock in the mains supply.
Water supplied from a tank can suffer airlocks because the system relies on gravity to operate, but not the mains supply which is pumped.
To my mind there are two likely causes.
A blockage has formed in the pipe or local water pressure is not stable, perhaps caused by another leak.
A simple test for leaks.
Ensure nothing in the house is using water because that will mask what you are listening for.
Listen to the mains pipe using a rod or solid stick, one end of the stick/rod on the pipe the other end pressed to your ear in your fist.
A hissing sound will indicate a leak.
The nearer you are to the leak the louder it will be.
You can also do the same test on the stop cock or water meter.

To check you are listening "properly" turn on a tap slightly and listen to the pipe. You should be able to hear the water flowing in the pipe.

 

[Lindyboo]

Thanks both for your replies.

I tried the listening-to-pipe thingy this morning but couldn't hear anything. That said, even when I opened a tap remote from the pipe I couldn't hear water. Unfortunately the only ear-accessible pipe is about fifteen feet (linear) away (plus about 4 ft vertical) from the replaced joint. The outside tap also has low pressure. The stop cock is in a very difficult spot behind the sink cabinet - would need a long stick and a good ear to access it. I have upper body and arm mobility issues which make such a cramped manoeuvre impossible.

The pressure has got lower since my original posting. If it drops further I'll give the water brigade another call (they said I should) to see if they can get someone out quickish. It's struggling now to fire up the combi for hot water.

My biggest worry is not so much what the cause might be, but in finding someone to put it right. There's a serious shortage of tradesmen in this part of the world (though we have an excess of cowboys to make up for it :lol: ).

To add to the frustration our mains stop cock is a quarter of a mile down the road ...

 

[Lime]

If you can't hear a tap running you are not putting/placing the stick on your ear correctly.
You need to experiment until you can hear water rushing in the pipe.
You do not need to be very near a leak or open tap to hear it and the stick can be as long as you need it to be as long as it is solid.
Wooden broom handles make good listening sticks especially for stop cocks in the road.
Your stop cock down the road would be a good place to start testing.
If you have a leak anywhere in your mains pipework the sound should be able to be heard there.

 

[Lindyboo]

Have given the water bods another call - pressure still dropping so fingers crossed for a visit from International Rescue. Meanwhile, Lime, am going in search of a wooden broom handle - curse these modern aluminium varieties ...

 

[agbagb]

I would suspect some crud got in the supply pipe during the repair. It has washed up (over the first day) to your internal stopcock and is now restricting the flow. I would turn off the supply, unscrew the tap from the body of the stopcock and then (briefly) turn the supply on to flush it out. A hose adapted to the stopcock body would be handy.

Easier said than done! I think you are going to need help with this one.

 

[Lindyboo]

I would suspect some crud got in the supply pipe during the repair. It has washed up (over the first day) to your internal stopcock and is now restricting the flow. I would turn off the supply, unscrew the tap from the body of the stopcock and then (briefly) turn the supply on to flush it out. A hose adapted to the stopcock body would be handy.

Easier said than done! I think you are going to need help with this one.

Hm, sounds plausible - and difficult. Mind you, better than having to dig up our newly-laid-at-staggering-expense-landscaped-gardens-and-patio, so I kind of hope you're right ...

They say that with age comes wisdom. I now know this to be true. When I was a young thing and always buying properties I could 'make my own' I thought those grumpy older folk who just wanted a house 'ready to live in' were off their rockers and had no fit place in the design of the universe.

And now, I am that soldier.

 

[kreyszig]

I wonder if something like this would be of any use if you're having trouble hearing the pipe:

mechanics stethoscope

might not be long enough but the direct feed into your ear looks handy

 

[Lindyboo]

I wonder if something like this would be of any use if you're having trouble hearing the pipe:

mechanics stethoscope

might not be long enough but the direct feed into your ear looks handy

Thanks for that info. Will keep it on hand. Just had a call advising that International Rescue will be arriving before 4pm today. Will it be tears of sadness or joy, I wonder? Either way, everything else here is wet so ...

 

[Lindyboo]

The Waterboy has been and done various tests. He is '100% confident' that there are no leaks, so I wipe my brow as I type this. The fluctuation in pressure has him slightly bamboozled, but matters it seems were possibly compounded by an unreported major leak locally. Our pressure improved when this had been fixed (though it doesn't explain why our only neighbour who shares the supply was unaffected). He's advised us to monitor things over the next few days and report back if fluctuations continue. I informed the insurance who seemed not to understand what seems to me a simple concept that when the engineer says there are no leaks, it means there are no leaks.

Anyway, I might get a better night's sleep tonight (was up at 5, fretting). Thanks all for your input and advice.

 

[Keithj]

One sign that there's air in the pipes is "water hammer" - if you turn off the flowing tap very sharply you hear a "bang" as the air in the pipe repressurises. If your pressure is very low to start with, that's not much help because there won't be enough to make the bang in the first place. It's worked for me, indoors, though.

I'm inclined to agbagb's diagnosis, that some crud has got into the pipe somewhere.