New Bathroom - Cold Supply Intermittent

[tigerjimbo]

I've just fitted a new bathroom suite, toilet, bath and basin and new radiator.

The bath was moved through 90 degrees and the taps were moved to the other end of it. The basin was moved a short distance as well.

The cold supply is tank fed from the loft and the hot is via the hot water cylinder which is next to the bathroom.

Bath supplies were originally run in 22mm copper and that is what they have been re piped with, adding a check valve (due to bath mixer taps with shower head) and 22mm isolating valves. Taps are connected with copper, not flexis. All fittings are end feed.

The bath mixer is suitable for low pressure systems


Basin supplies are 15mm, again with isolating valves.

The basin taps are fine, both hot and cold providing good flow and pressure.

Hot supply to bath is fine but the cold is intermittent.

Sometimes when the cold is turned on there is a slight gurgle and sometimes a trickle of water.
Sometimes turning the lever over to the shower seems to allow the cold to come through. This doesn't always work and sometimes the cold can be open indefinately without anything happening.

It appears that the only certain way to get the cold flowing is to open the cold bath tap and then turn on the cold basin tap. Hey presto, service is restored.

Once the cold is flowing, pressure is good as is the flow and I can turn the supply on and off as normal. I can then use it as usual for a good few hours, sometimes up to a day or more.

Any ideas what the problem could be?

Any help would be appreciated.

James

 

[tonybhoy]

Sounds like an air lock or blockage in the pipework.

I would remove the NRVs and iso valves to check if I were you.

 

[tigerjimbo]

Thanks for the reply.

If it was an airlock, where would it be getting back into the pipework, bearing in mind I can get it all flowing freely with no problems. If the air is getting in fairly quickly I would anticipate the water would come out. I am aware that air molecules are smaller than water, but even so.....

Am I missing something obvious?

Could a faulty check valve cause this problem. The hot supply to the bath is plumbed identically to the cold and works perfectly?

Thanks

James

 

[tonybhoy]

Thanks for the reply.

If it was an airlock, where would it be getting back into the pipework, bearing in mind I can get it all flowing freely with no problems. If the air is getting in fairly quickly I would anticipate the water would come out. I am aware that air molecules are smaller than water, but even so.....

Am I missing something obvious?

Could a faulty check valve cause this problem. The hot supply to the bath is plumbed identically to the cold and works perfectly?

Thanks

James

Sometimes air gets trapped in the pipework.

Cold feeds can be murder to clear of airlocks(a dip in the pipe in the loft for example)cause it's not so easy to force water up them they way you can with the hot or open the sludge at the cylinder to clear an airlock on the hot supply.

You might have to disconnect the CF at the tank and blow through it with the bath tap open then reconnect.

I would look at the other valves too though