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Mixer Taps low hot pressure despite decent hot flow rate in pipes

Postby strike101 » Thu Feb 02, 2017 10:06 pm

Hi Everyone,

I'm hoping somebody can help.

I have a problem in my bathroom. My mixer tap (i have tried several) is giving me very poor pressure hot water. If I turn the mixer to full cold, the water if cold and with food pressure. Any other setting on the mixer (full hot or in the middle) gives me pathetic flow. Basically as soon as it introduces any hot water the tap produces low pressure water.

I measured the flows of the hot and cold taps and I have found that;

Hot Water: 7L/m
Cold Water: 12L/m

Through the mixer however I am getting a pathetic 2.5L/m

I have tried three different mixer taps and they all give me more or less the same problem.

Now my hot water is 7L/m and cold water is 12L/m so I dont understand why as soon as I connect the tap, the flow becomes so low (2.5L/m). The flow rate was measured from underneath the sink, the last place before the pipe is attached to the mixer.

Any suggestions would be welcome
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Simply Build It

Postby GayEddie » Fri Feb 03, 2017 8:10 pm


This is a common problem people buy taps they like or look nice but the problem is the flexible tap tail will sometime have a very small bore which is fine for mains pressure hot water systems but when you rely on gravity from your tank in the loft people notice a big reduction of pressure.

They do mixer taps for low pressure with large tap tails 12mm or 10mm also you could put on your hot side a full bore isolation valve every little helps ... +CP/p11495
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Postby lets have a look » Sat Feb 04, 2017 5:40 am

I have been changing a few sink mixer taps recently as the bore in the flexi pipes are to small.
lets have a look
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