Airlock

[barker41]

Problem with airlocks

Could anyone help with the following problem regarding the cold feed from the loft tank to the toilet and sink in the bathroom
The original bath had 22mm runs of hot and cold water feed with 15mm branches off to toilet and washbasin.
The new bath has no taps as it is filled from the new shower unit, which is a combined
Shower and bath filler system with completely separate pumped feeds of hot and cold water.
The toilet and washbasin uses the original pipe modified to suit new units

The old feeds to the bath where capped off at the bath end, and the pipe still feeds the toilet
And washbasin, also the down stair cloakroom (toilet and basin) which has no problem they still work fine.
The problem is about every 3 - 4 weeks the supply to the washbasin in bathroom stops, which also stops the toilet from filling.
In order to get the system working again I disconnect cold tap tail from the 15mm feed and connect
A piece of pipe fixed to my wetvac and suck out till the water runs at full bore again, this always works
And it also gets the toilet working, but the problems back after a month.
The hot water supply works perfectly ok

The new tape at washbasin is a Axor Citterio single lever operation tap for hot and cold
The tails from the tap head are only 10mm dia giving about a 5mm hole for the water to pass
And the same for the toilet one inside the system.

I am wondering if the feed hole size is part of the problem and do they work well on gravity systems
On the other hand the hot feed to the same tap with same size hole has never stopped working since
Installed and the cylinder is on the same level.

 

[swidders]

Please clarify one point:

Shower and bath filler system with completely separate pumped feeds of hot and cold water.

Does the pump get its cold supply from a dedicated outlet from the cold water tank for its sole use?

 

[barker41]

Hello swidders

yes the shower and bath fill are completly separate with dedicated 22mm cold feed from tank to pump and hot feed via essex valve from cylinder to
pump so the two systems are not connected.
regards

 

[swidders]

So, the question is - how is air getting into the pipework to create an airlock? The only way I can imagine is through the tap - when turned on the hot water is somehow creating a trapped bubble which works its way back up the pipes. If this is the case, the only solution, other than tracing the pipework back up to see where a high point exists, it to install a non-return valve between the tap tail and feed pipework.

 

[barker41]

hi swidders
thanks for the advice I will keep this in mind, I have also found out today that it is possible to change the 10mm flexi tap tail that came with the tap
to 15mm tails which will only leave a very small portion 6mm at the tap.
maby this will work,will try this first, if not will add non-return valve.
I was also informed by the plumb centre that most of the foreign units work on mains pressure not gravity. the last option would be to divert the
feed from tank to mains pressure.
will not be doing any thing till the airlock returns.

 

[swidders]

last option would be to divert the
feed from tank to mains pressure

....or install a pump on the feed somewhere.

You may need a non-return valve on the hot to prevent cold mains forcing its way up the hot pipe, or preventing its flow.

By the way, no I don't have shares in non-return valve manufacturers!!