Combi boiler + sink mixer tap with pull-out shower head?


4 Jan 2012
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United Kingdom

I have a Worcester Bosch 30CDi combi boiler in the ground floor kitchen. There are no hot or cold water tanks in the house. Upstairs is a bathroom with an electric shower (i.e. independent of boiler), and a sink with a 15mm hot water pipe from the boiler, and a 15mm cold mains feed. The taps are separate.

Now, in winter, the power shower has lost a lot of power because the cold mains that comes in is - so cold! It was noticeably more powerful in summer (new Triton only installed this summer).

So, I have an idea.. The sink is next to the bath. I am thinking of replacing the hot/cold taps in the sink with a monobloc mixer tap with a pull-out shower head on a hose, and use it to shower in the bath! This one in fact: (there are detailed pics lower down the page).

My worries are about water pressures from these mixer taps. If I turn the current separate sink hot and cold taps on full, water comes out at what looks like a pretty good flow rate. If I join the 15mm hot (combi) and 15mm cold (mains) supplies into this mixer tap, would I get a decent flow rate for a powerful enough shower? (I can fit my own shower heads with multiple settings, if that helps). I am also a bit worried if this 'lever' type tap would for some reason give a smaller rate of flow compared to the 'twist' types.

A few more details: there is a bath tap in the bath which also gets hot from the combi and cold from mains, but it has no shower hose attachment! The flow rate from that is excellent (but I guess it has 22mm water feeds, not 15mm, if it makes a difference). And it's such a weird massive faucet that you cannot fit those push-on rubber tap/shower converters onto it. The Hozelock garden hose clip-on also doesn't fit. And replacing the tap would be a major hassle which is why I wanted to try the sink mixer tap idea.

Many thanks for any input!
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Seems a bit odd to have the shower coming off the basin.

I would either change the bath mixer tap for one with a shower hose or install a separate shower mixer valve and get rid of the electric shower. Electric showers don't give a lot of pressure and they are more expensive to run.

The flowrate will depend on your incoming mains flowrate, assuming it is greater than and the HW output of the boiler, which is 12.6 ltr/min. :)
Thanks for your reply. If only it were simple enough to change the bath tap.. It's an ancient rented property and the bathroom is a pretty horrible hodge-podge of DIY horror jobs. Some eejut has even put lino over the bath side panel so it runs up continuously from the floor, and will be a pain to remove. Still, have the plumber coming in tomorrow for an unrelated issue so will ask about replacing the bath tap. Shouldn't be impossible.

But, to my eyes at least, if the water flow out of the bath tap (hot from combi and cold from mains) is ok - it is really gushing out - then feeding a shower hose from the sink should also be ok..? I'm just unsure because of the lever tap on this mixer, and the 15-22mm pipe difference between sink and bath.

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