2 questions

[roofrack]

In the last three weeks I have noticed a noise coming from the kitchen sink. The noise sounds like moving water in the mains cold water pipe. The house is about a year old, so I got the builder round and he said that the mains pipe entered the house under the kitchen sink. He noticed a dripping from the overflow pipes at the back of the house coming from the water tank in the attic and I thought that was the problem.

I went into the attic and bent the ballcock arm of the tank down to stop the water entering the tank below the overflow. I ran the bath with hot water and watched the water drain out of the tank. I thought Problem sorted. Not to be, next morning I checked the overflow pipes at the back of the house and one was running a steady stream of water. Into the attic again to check the ballcock and it is underwater. I ran the bath with hot water again and watched the water drain out of the tank, the ballcock seems to be working as it did not start to let water into the tank until the water level was at the correct depth. I then noticed a drip from the the inlet, one drip about evey 5 secs.

2 Questions:

1. Would this drip be enough to fill a tank overnight, so there would be a steady stream of water from the overflow pipes in the morning?

2. If the noise from under the sink is mains cold water coming into the house, where is it going? I have turned off the mains water which is out on the street and the noise stops. There is no sign of a leak.

Thanks for you help.

 

[JohnD]

Have you got a mixer tap, probably a shower but might be the sink, where the hot is tank-fed and the cold is mains fed?

If you have, are there service valves on the pipes feeding this tap?

Is there a service valve on the pipe which supplies the ballcock to the cold water tank?

 

[baxpoti]

Have you got another tank in the loft?

A small tank above the cold water tank?

 

[roofrack]

JohnD
I have a mixer tap on the kitchen sink where I can hear the mains water noise. The cold water comes from the mains and the hot is tank fed.

If you have, are there service valves on the pipes feeding this tap?

Im not sure if there are service valves on the pipes feeding the mixer tap. Could you tell me how to check this.

Thanks for your reply.

 

[roofrack]

baxpoti
Yes. I have another small tank in the loft. It is beside the large tank on the same level.

This tank has an overflow pipe aswell but it does not drip. I dont know what this tank does?

Thanks for your reply

 

[JohnD]

Most commonly a service valve will look like this, where you turn the screw head. Sometimes they have a lever like a washing machine tap. They can be incorporated into the fitting on a flexible braided hose.

It often happens that the leak in a mixer tap will allow mains pressure cold to feed up into the hot water pipe. This is more common with bathroom or shower mixers since UK sink taps are designed to prevent it.

The small tank in your loft feeds the boiler. It should be a bit lower than the level in your big cold water tank.

 

[roofrack]

JohnD
I think I have seen a service valve. I must check tonight to make sure.

Are you saying that the leak will be into the hot water pipes, which would in turn back up and fill the tank in the loft?

I have noticed that when you stop running the hot water. leave it a few seconds and turn it back on the water is really cold straight away (where you would expect it to be hot as you have just turned off the hot water) and then after running it for a about 5 seconds you get the hot water back.

Cheers

 

[JohnD]

yes, that is what I mean. If there is a service valve it should stop the backflow to help you diagnose it.

You may be able to detect it by feeling the "hot" pipes to see if they seem to have cold water flowing up through them.

You can fit non-return valves or buy a better tap. UK taps can have a Water Council approval I think (bit hazy on this) and low-priced imports may have the problem you describe.

If you have individual taps (not mixers) then of course the water can't pass from one to the other.

 

[joe-90]

If it is a case of cold water pushing hot water back due to a missing check-valve then the water in your tank (and the water that is overflowing) will be hot.

 

[BoxBasher]

STOP! Don't buy any new taps or start mucking about with check valves/service valves yet!
A mixer tap pushing back will only happen when the tap is being used, not overnight.

Check your toilet cistern and both tanks in the loft. If any of these is overflowing then fix them it. (Not just by bending the arm on the ballcock, but by repairing/replacing them). If it is none of these then start thinking about what else it could be but get the simple stuff done first.

If you don't feel like taking the lid of your toilet cistern (if its got buttons in the lid) then flush the loo and see if the overflow stops. If it is the cistern overflowing then it will stop until its full again.

With regards to a steady drip - it will not create a level in the tank capable of causing a steady flow. What drips in, will drip out at the same rate.

Regards to the noise of water flowing in the mains pipe, close the internal stopvalve (which should be under the kitchen sink if that where your mains supply comes in). Let us know if this stops the noise.

If your house is only a year old then why isn't the developer sorting things out for you?

 

[joe-90]

A mixer tap pushing back will only happen when the tap is being used, not overnight.

That's not so. A mixer shower will push back when it's off - not when it is flowing. When it is flowing the pressure isn't there to push back. It's the two flows in equilibrium that stop the water flowing ie - both mains fed or both tank fed.

 

[BoxBasher]

That's not so. A mixer shower will push back when it's off - not when it is flowing. When it is flowing the pressure isn't there to push back. It's the two flows in equilibrium that stop the water flowing ie - both mains fed or both tank fed.

Yes, however may I quote the following:

I have a mixer tap on the kitchen sink where I can hear the mains water noise.

I think we are confusing the situation by suggesting CV/SV's at the moment. Start from the beginning and rule out each thing in order. We still haven't identified which tank/pipe the water is overflowing from so rather than jump to conclusions about whats causing the problem, lets make sure it isn't something glaringly obvious.[/quote]

 

[joe-90]

Yes. I agree. Come to think of it, if the house has a shared water main you can sometimes hear a neighbours tap. Has he checked his water meter when he hears this noise? It may be noise in the general system.

 

[BoxBasher]

if the house has a shared water main you can sometimes hear a neighbours tap.

Better bloomin' not have if its new build...

I'm still unsure why the developer isn't sorting this out for you. (although if he's installed it as well as I'm guessing then you're probably right to DIY)

 

[roofrack]

Thanks for all the replies.
I think JohnD has it sussed.
I have a service valve on the hot and cold water pipes going into the mixer taps in the Kitchen. I turned the hot water one off with a screw driver and the noise stopped immediately. The steady stream from the overflow pipe stopped after a few minutes and this morning it was nice and dry out the back for the first time in weeks.
Happy Days

Is it easy to replace one of these service valves?
Looks like two nuts to loosen with a spanner and Just replace?

I will need the water off, but if its coming down from a tank how would you stop this.