Water pressure


Postby jackhammer » Sat May 17, 2008 6:56 pm

I have fitted a new bathroom suite recently and new taps - the taps are the half turn ceramic mixer taps to the bath and sink. I have also fitted a thermostatic shower valve which i have taken from the bath hot and cold water inlet. Today i have fitted the toilet and the problem i have is that there is not enough water pressure to fill up the toilet cistern. In the airing cupboard on the main cold water feed supply which supplies the upstairs of the house there is a tap which i have used to shut off the water supply (to the upstairs only) - this tap is a bit dodgy as it does not completely turn off the water supply there is a slight drip when i turn it off - do you think it might be something to do with this. The feed which comes into the toilet is the lowest point in the bathroom. Any help or suggestions would be greatful as i seriously need to flush the toilet!!!
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Postby plumbbob » Sun May 18, 2008 9:26 am

The first suggestion is a bit of debris from plumbing work has entered the cistern vale and blocked it. Strip it down and examine.
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Postby jackhammer » Sun May 18, 2008 1:19 pm

I've done this and couldn't see anything that shouldn't be there, also i can easily put my thumb over the tap and stop the flow without it spraying everywhere so that suggests a pressure problem.
It was fine with the old toilet but then that was a normal ball float system set up and this one is a new toilet with the built in over flow centre button flush etc.
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Postby plumbbob » Sun May 18, 2008 3:00 pm

This suggests that the cistern is connected to a low pressure feed from a header tank say? This may have worked fine with an old style ball cock as the the valve can be fitted with a low pressure device but a new Torbeck style are high pressure only. If this is the case, the toilet needs re-plumbing to the high pressure mains supply. Is the bath cold low pressure? Can you stop that and the basin?

I had assumed you did not have header tanks because of the way you describe fitting the mixer shower.
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Postby jackhammer » Sun May 18, 2008 7:37 pm

I can stop the flow of water with my thumb on both the basin and the bath. The upstairs feed does come from a header tank and now i am wondering should i have never fitted the shower? If so why should i have not done this as all i have done is taken a hot and cold feed from the supply to a thermostatic shower valve. I have since been to a local hardware store and purchased a new valve for high and low pressure WC's and it now fills up the cistern within 2 minutes. I can change the diaphragm to a low pressure one which will do it even faster. I am concerned about the last post saying about the shower being fitted to a header tank (should i have not done this?). Cheers for the replies.
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Postby plumbbob » Mon May 19, 2008 8:17 am

Change the diaphragm in the valve for low pressure or change the supply to a mains feed (where it ought to be) and that should sort the problem with your toilet.

The shower valve can only be connected to the feeds under the bath in a high pressure system such as a combi for example. The mixer should have a dedicated cold feed directly from the header tank and a hot feed as close as possible to the outlet of the hot water cylinder.

This is to ensure a constant flow of hot and cold water to the mixer regardless of any other usage of water in the house. If the shower was in use and the cold tap turned on, it is possible someone in the shower could be scalded.

Also as a further point, basin cold taps should always be connected to the mains supply. The water must be drinkable, and stored water is not designed for such use.
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Postby chris_on_tour2002 » Mon May 19, 2008 10:03 pm

hi plumbbob,

[quote]basin cold taps should always be connected to the mains supply. The water must be drinkable, and stored water is not designed for such use.[/quote]

is this a building reg requirement? or just advisory? i've always believed that the cold tap at the kitchen sink is the only mandatory mains feed for drinking. just curious.
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Postby plumbbob » Tue May 20, 2008 11:13 am

It is true that at least one tap must be supplied directly from a supply pipe for drinking and cooking purposes. In a dwelling, it is assumed that all taps will be used for drinking water and therefore must be made potable by either being supplied directly from the mains or from a 'protected' header tank.

Some years ago, it was required that a reserve of water was required in case of a mains failure and this was why some cold taps and toilets were fed via a header tank. This is no longer considered a necessity and the regulations advise that all cold supplies should be direct feeds.

Frankly, in my opinion, it is down to what I see in header tanks that puts me off drinking any of this water. The lids never fit properly, and therefore, egress of all manner of things is possible. Yuk!

How about the guy in the next post that has a tank full of loft insulation?
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