Mains pressure not quite man enough for kitchen mixer?

[sanderr2]

Hi,
the cold water in our kitchen mixer tap has been slowly dying - it hasn't been great since we moved in but it had slowed to a trickle. The pressure at other mains fed taps seemed fine so I figured that the kitchen tap was past it's sell buy - washers etc.

I bought a new kitchen mixer tap online and connected it up only to find... no cold water at all!

I've checked the pressure all the way up to the tap and it seems strong. I put the cold feed onto the hot tap and voila - cold water. So I began to think there must be something on the cold side of the tap deliberately restricting the flow to balance the relatively low pressure hot coming from the combi against the high pressure mains fed cold.

I took the taps apart and sure enough, on the hot tap side there are two clearly visible holes into the final part of the tap assembly while on the cold side I can't see anything. Putting my lips to where the cold tap would be and blowing very hard finally yielded some flow (albeit my hot air) through the tap.

So my suspicion is that although the mains cold feed feels pretty decent it
isn't quite man enough to push through whatever valve exists on the cold side.

I thought that one way around this might be to drill a small hole on the cold side and enlarge it until the cold is flowing (but hopefully not too much to prevent any hot from flowing).

Presumably the alternative is a low pressure mixer tap - but with the relatively high cold water pressure won't that prevent successful "mixing"? Any wisdom would be very much appreciated.

Thanks and apologies for the lengthy post,
Rob

 

[ratonnastick]

Sound`s like your cold inlet may have a check or non return valve fitted to prevent cross contamination of the cold main, this would restrict the flow rate from the tap.

The tap you purchased would have given a minimum pressure it will operate with, have you checked this?

You could remove the check valve but this is not strictly to the book, on the same note most mixers do not normal come with check valves installed and rely on the plumber installing them before the tap connections but most don't bother. Be warned this can cause other plumbing issues.

Note:
Pressure and flow are not the same thing, a big pipe say with .5 bar pressure can deliver more water than a very small pipe with 2 bar pressure.

So low pressure with small openings = no chance