DIY Doctor UK DIY Forums

New on here, but hoping for some quick assistance. Has anyone plumbed in a kitchen mixer tap with spray head attachment. You know the type, singe hole stainless steel 11/2 bowl sink and ss tap, single lever mixer art base rising up to a horizontal swivel 'neck' for the main tap (with second on/off 90 degree tap at the end) and an outlet for the main tap.

Rising up above the main horizontal outlet is the attachment to a flexible hose in a large coil spring leading to a spray outlet which resides in a swivel holding arm projecting from the main body.

OK, I plumbed it in yesterday replacing an older leaking swan neck two valve mixer. I had isolation valves under the sink but instead of the previous soft copper tails this one has long flexible braided connectors so I used adapters after the isolators for go from 15mm copper to a half inch bsp screw to fix the flexibles to.

On refilling the system the cold works fine. The hot has vey little flow. I can only think that I have possible restricted it with some stray ptfe tape OR something else in the tap is introducing additional resistance on the hot side. (Mine is a hot cylinder with loft header tank system).

Now, when I put the main valve to mix flows and close the outlet at the end of the horizontal arm (ready to use the spray head) I can hear the cold flowing back up my hot pipes and if left on would eventually overflow the header in the loft I guess. Although it is less noticeable I think I get the same effect when just using the mixer tap normally (ie cold flowing back up the hot side).

What is normally there to stop this happening? I can imagine a non return valve on the hot side would possibly cure it but this is surely not an essential but unmentioned part of the installation.

Any helpful thoughts gratefully received.

Do these taps come in types for combi's only by any chance - it was not marked as such but that might explain it if they required equal pressure on hot and cold sides ? (I do hope not).

You need to check the taps instructions and/or with the manufacturer/supplier. The tap could be meant for use on mains pressure systems not tank fed.

alfazzr,
Unfortunately you have a tap intended for a combi boiler.
Fitting a non return valve in the hot feed will further restrict the hot flow.
You have two choices: fit a pump in the hot water supply or scrap the tap and replace it with one for low pressure. Be wary of claims that taps are suitable for low pressure - even some of the ones claiming this do work but take forever to fill a bowl with hot water.
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