water flow

Postby mankind » Fri Oct 08, 2010 2:35 pm

Hi can anyone advise me on this problem please ?
Our newly installed bath has taps with a 15mm feed but the rest of the pipework supplying the hot and cold water is 22mm. the difference in diameter is taken care of by flexible hoses which connect the 22mm to the 15mm copper pipework. The hot and cold water flows from the 22 into the 15 and into the bath via individual taps (Not a mixer tap).
The flow rate out of the taps is very slow, what can I do to improve the flow rate ?
The hotwater cylinder is in an airing cupboard at the foot of the bath and the cold water tank is in the loft directly above the cylinder.

Any ideas ??

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Simply Build It

Postby plumbbob » Sat Oct 09, 2010 2:10 pm

Are you sure the taps are bath taps? Bath taps have 3/4" connections as the smaller 1/2" basin taps will not allow sufficient flow. So the connections should be 22mm to 3/4".

If you have a low pressure system, do not use flexible pipes as they restrict the flow far too much. The taps must have 22mm direct couplings to give unrestricted flow and certainly nothing as small as 15mm should be involved.
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Postby mankind » Wed Oct 13, 2010 4:08 pm

Hi Bob,

I purchased a complete bath kit from B&Q. The hot and cold water fixed pipework is connected to individual flexible hoses that connect to a bathfiller via separate hot and cold taps. The kit also includes a telephone system showerhead, which also has a flexible hose.
So the water flows through the copper pipework into a flexible hose, then through a tap/valve and into the bath filler where the hot and cold are mixed.

My main pipework is 22mm but the taps/valves as supplied with the kit require 15mm.

Should I speak to B&Q to see what they suggest ?

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Joined: Mon Feb 15, 2010 4:56 pm

Postby plumbbob » Thu Oct 14, 2010 4:27 pm

My guess is these taps are only suitable for fitting to a high pressure system. It is often the case that with DIY stores customers are left to buy products without proper guidance so it is always a bit of a gamble. Products are not always clearly marked as to the suitability for connection to a low pressure system. Low pressure taps must be capable of working at 0.1 bar. Anything above 0.5 bar are high (mains) pressure only.

I have seen posts here in the past where customers have taken this up with the stores which has resulted in a suitable solution, but with your taps, the options are limited.

I assume if the connection to the cold is 22mm, then it is fed from the header tank??? If so this could be rectified by directly connecting it to the incoming cold mains which is where it should have been in the first place.

Of course, no such option is possible to the rectify the poor hot flow. If the flexible tails are cheap and thin, replacing with a better wider bore pipe may increase the flow, but you might still be disappointed.
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Postby gilo » Thu Oct 14, 2010 10:06 pm

All the above is true but just to add if the tap has a airator which is a metal or plastic grill that is inserted in the end of the tap spout if you take this out this should improve the flowrate. We import taps from Italy and the Italians recommend that we remove these if the water pressure is low.
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Postby Skids » Sat Oct 23, 2010 4:48 pm

Hi Mankind,

Your problem is B&Q.

You do not state if your water is heated be combi or system boiler/cylinder.

If the supply pipes are 22mm I would conclude hot water comes from a hot water cylinder?

If so you need to go back to B&Q and get the taps changed for low pressure ones.

Do not use flexi hoses

B&Q should have asked what system you have in the first place!!

All the best

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Joined: Fri Dec 21, 2007 6:35 pm

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