Home plumbers of STW, I have just fitted a new tap in the bathroom (tank fed cold and immersion hot water feed). Old tap seemed to be ok, not crazy high flow rates, but sufficient.
New tap has a 3l/min flow rate as an 'eco' tap and also is 3/8" tap tails compared to the older 1/2" tails.
Taps are connected to isolator values and I have no access to any stop-cocks for these feeds (boxed in with tiled over area I think).
If I got to a 5l/min tap rather than a 3 is this going to improve things enough to make washing hands feel like they are being washed rather than slowly wetted?
A tap which has a higher l/m flow rate at a particular pressure will be better, yes. Searching under 'low pressure bathroom taps' or for one with the lowest stated minimum water pressure eg 0.1 or 0.2bar will probably come up with the best result for your dribble of water.
Is it possible that the tap feed is 'turned down' at the isolating valve, or is your pressure pitiful throughout the house?
I set the isolator valves back to the same as they were for the old tap, the old tap had a horizontal spout and water came at a reasonable rate.
Water pressure is generally ok around the rest of the house, I suspect the bathroom fitters set a valve for this tap somewhere then boxed it in, which is a problem with an older house with surface pipes and a 'modern' bathroom design.
I have mains pressure cold but its pretty poor at the best of times. Running a bath was painfully slow, changed the tap to a low pressure one designed for gravity fed systems and it now fills much quicker.
I think you can also get full bore isolators so might be worth checking they are available and if your current ones are limiting flow
3/8" plumbing fittings are often 1cm internal diameter and a bit less than that at the valve - it's likely to be the tap valve internals where the cross section is the smallest and restricting flow. If there's a water saving foaming thing or a pre-valve filter try taking it off. In that the tap seems to be the limiting factor then yes a higher flow rate tap would improve matters, but more head would improve it a lot more.
Switch the isolator valve for a full-bore one? Standard ball valves have a flow restriction due to the design.
https://media.screwfix.com/is/image/ae235/46860_P?$fxSharpen$=&wid=257&hei=257&dpr=on
This above not the one below
https://media.screwfix.com/is/image/ae235/65251_P?$fxSharpen$=&wid=257&hei=257&dpr=on
Have you checked what the actual flow rate is (jug, stopwatch)? I've never quite worked out how flow restrictors work but IME they seem to depend on pressure (ie are not very accurate anyway) and gravity fed UK systems are very low pressure and don't work well with them.
Our house is on mains pressure for everything, with a 3.5 bar limiter on at the source. Some of that will be lost over the pipework but 3.5 bar =10m of head. Your bathroom, with a tank in the loft for pressure just above it, might only have 2m or so of head.
You probably need a different tap.
I'd like to bet a 3/8th tap has a smaller bore than even the isolator in the bottom pic. I've just measured the bore of a 1/2 isolator like in the bottom pic. A 9mm drill is go and 10mm drill no go so the bore is about 9.5mm - the same as a valve in a typical 1/2 tap - a 3/8 tap is going to be the same at best or smaller. I still think the problem is the tap (and lack of head). The tap needs to have a bigger valve opening than the new one our OP has bought.
I've ordered another tap, hopefully collect and fit it before I have to collect my wife from the airport, then she'll not need to know of the mid-job replanning needed.
Thanks for the advice all, I suspect the low flow tap added to limited tank based water pressure are all contributing to the trickle, so hopefully a step up in flow rate and full bore connectors will solve all my woes, we'll see!
3.5 bar =10m of head
3.5 bar = 35(.7) m of head.
Apologies, could not help myself.
Retired engineer.
Our head tanks sit on the ceiling joists so a very low head. We always have to look that little bit harder for low head isolation valves and taps.
Gravity fed low head shower mixer taps are not really that low head these days so I ended up installing some in-line 'SP2B Automatic Shower Power Booster Pumps' which have proved effective and maintenance free for 2-3 years now. They are easy to fit and can be used to boost pressure/flow to a whole gravity fed water system not just showers.
https://showerpowerbooster.co.uk/
They also sell low pressure shower heads though I have no experience of them.
https://wrightchoiceshowerheads.co.uk/shop/
Hopefully someone finds this useful.
Ah, the shower head is ridiculous (40cm round head) so yes, we have a pump to provide water to the shower, my wife can still drain the immersion tank in a single shower though, to be fair the fitter did say we might want to consider a bigger tank/boiler replacement at some point as we are still on an old back boiler which just runs and runs with a yearly spruce up. We've lived here for 16 years and it wasn't even close to new when we moved in!
Stuck the new tap on, have a gentle stream or water again which is a significant improvement on the previous tap. Cheers for the input all.
Wish I had a low pressure problem. My inlet pressure is 6.25 bar so had to get a 3 bar pressure relief valve fitted after one of the BSP fittings started leaking. Saved a fortune on the water bill for mini me showers
