Low flow rate after plumbing work done - seeking advice

13 Mar 2006
Reaction score
United Kingdom

We have recently had our kitchen taps replaced as part of a refurb. The work was done while we were away and the plumber replaced my existing tap tails (which had integral stop valves) with separate stop valves and new tap tails. Therefore the stopcock was turned off :)

On our return, the 'water pressure' had obviously reduced where we notice it. I have spent several weeks educating myself off and on and while I still have some work to do I would like to know if I am on the right track. Obviously we have recalled the plumber who claims everything is operating within spec!

Our house has a high pressure water system. The water enters from the rear after feeding a yard tap and then gets to our internal stopcock. Flow rate at the yard tap is at least 22 l/min. After the internal stopcock there is an immediate branch to the bathroom. Cold water flow rate at the bath and sink taps (all mixers) is around 9 l/min.

After the branch the cold water feeds the washing machine, sink, dishwasher and combi boiler. The cold water flow rate at the kitchen mixer tap (without aerator) is no more than 5 l/min.

The mixer shower in the bathroom is much more modern than the main bathroom pipework (involving extensive plumbing work on installation) and is the main source of frustration to my wife (and therefore me!). The cold water flow rate at the shower is 5 l/min - it is currently impossible for me to positively check where this cold water is branched from. For the avoidance of doubt, flow rate at the shower is visibly different to our previous experience and is why I am doing this troubleshooting.

If we call for hot water anywhere in the house then the combi kicks in. After around 10 minutes of sustained, hot/cold mixed flow the hot water fades away... my working assumption is that the cold water flow at the combi is 5 l/min and that the combined effect of mixing cold and hot water over a sustained period is causing the combi pressure switch to reset because the hot water flow rate has dropped below threshold. Note that the combi pressure gauge is reading fine.

We also have a front garden tap which is controlled by the house stopcock. I do not yet know where this branches off the pipework in the kitchen (it runs under the floorboards the full length of the house). But the flow rate at this tap is at least 9 l/min.

I'd appreciate any comments/words of encouragement etc...!
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Change internal stopcock to a lever valve and replace any ballofix isolators to full bore.

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