Repeated Airlock in Bathroom

[PaulB100]

Hi, Can anyone advise as to why the cold water to my bathroom keeps airlocking?

This originally happened about 12 months ago and has happened 3-4 times since.

It’s an upstairs bathroom, fed from a tank in the attic. The tank is about 8 Meters away and feeds a bath, sink and toilet. The tank seems to be always full of water so no air is getting in there.

The first time it happened, I called a plumber out and he vacuumed out the cold tap until water flowed, I thought that would be the problem fixed. All was good for about 6-7 months and then it blocked up again. Instead of calling a plumber I cleared the air myself, I connected a hose to the mains tap downstairs, and forced water up the bathroom taps, this resulted in lots of air bubbles being forced into the attic tank, and then everything worked OK.

It seems to have become more regular now though, My fix only lasted about 2 months, so I repeated the process again, which worked, but it only lasted about 6 weeks this time. Now I seem to have to repeat it every 3-4 weeks.

I do wait until all the bubbles of air stop going into the tank and run the sink tap / fill the toilet so I am fairly confident all the air is out of the pipes when I finish.

I cannot think as to why it keeps happening. It worked without problem for 10 years previously since I got our bathroom remodelled.

Our toilet is fitted with a bottom entry cistern fill valve, is there any way that this could be faulty? And allowing air into the system? The only reason I mention this is because it seems to be a bit noisier than it used to be when filling the cistern.

Any advice would be appreciated. Thanks

 

[John.g]

Is the bathroom HW fed from the attic as well, if so, is this also airlocking?.

 

[fowlerboi]

Do you have a teenager in the house who likes long showers?

 

[Chuck]

Check the gradient on the pipework between the tank and the outlets. If there are any places it rises rather than falls that will allow air to collect in the 'inverted-U' section.

 

[PaulB100]

Is the bathroom HW fed from the attic as well, if so, is this also airlocking?.

The HW is fed from the attic tank too, but there is no problems with airlocks on the HW. Thanks

 

[PaulB100]

Do you have a teenager in the house who likes long showers?

This is a possibility, we do have a shower in the upstairs bathroom fed from the attic tank. I might switch it on and see how quickly it drains the tank. Thanks

 

[PaulB100]

Check the gradient on the pipework between the tank and the outlets. If there are any places it rises rather than falls that will allow air to collect in the 'inverted-U' section.

The cold water feed leaves the tank in the attic at a low level, travels horizontally across the attic for about 5M, drops down inside my hot press vertically for about 2.5M and then runs horizontally about 3M to the bathroom. The only place the pipes go ‘up’ is from the floor of the bathroom to the toilet / sink / bath.
This pipework has been in place for about 11 years and never caused a problem until about 12 months ago. I will lift some of the boards in the attic and see if the pipe run has moved in any way.
Thanks

 

[PaulB100]

Is the bathroom HW fed from the attic as well, if so, is this also airlocking?.

Hi, thanks for the reply. Yes the HW is fed from the same tank but we have never had a problem with airlocks on this.

 

[Last Plumber]

The cold water feed leaves the tank in the attic at a low level, travels horizontally across the attic for about 5M, drops down inside my hot press vertically for about 2.5M and then runs horizontally about 3M to the bathroom. The only place the pipes go ‘up’ is from the floor of the bathroom to the toilet / sink / bath.
This pipework has been in place for about 11 years and never caused a problem until about 12 months ago. I will lift some of the boards in the attic and see if the pipe run has moved in any way.
Thanks

It needs to have a very slight fall at least, throughout its run. No up and down. Even a slight rise and fall can collect air.
The water in the tank when freshly filled is aerated and this air can collect in a high point in pipework.
If the ball tap is at the same end as the outlet, that can in some cases cause an issue too due to a large volume of aerated fresh water and surrounding air splashing into the tank over the outlet whilst water is being drawn off.

 

[Chuck]

I will lift some of the boards in the attic and see if the pipe run has moved in any way.
Thanks

Before doing this, check the level in the cold water store tank while someone runs a bath to make sure it stays at a reasonable level above the outlet.

If possible, use a 'water level' (a length of tubing) to check the fall on the pipework. Don't assume the joists are level without checking; houses, particularly if they are built on clay, can tilt slightly over a period of years (or even after a long period of wet/dry weather) due to subsidence and/or heave.