Classic bath tap with severe low flow rate problem

[alex889]

Hi guys,

I've got a classic style bath tap which has a really low flow rate. I was checking all my taps to ensure flow and pressure is consistent and after that today I decided to open the bath tap to check inside.

I found the tap very clean, no signs of limescale, but the middle part of the mixer between hot and cold taps has like a T juntion where I can chose the tap to fill the bath of the shower head. That mechanism to select between the two is what restricts the flow massively. I'm trying to even understand how water flows through it as viewing from the tops it seems to not have any gaps.

Anyway, I'm thinking here, do I need to get a bath tap that doesn't have restrictions like this? Can I do something to this tap as it is?

Thanks!

 

[dilalio]

What flow rates are you getting from this valve and others? Measure in lpm.
There are 000’s of valves out there and it’s either a poor one of them or problems lie elsewhere... impossible to tell without specific details or eye’s on.

 

[Madrab]

The rod on the lever moves the diverter valve up or down. When moved down then the valve seals the lower outlet, the flow then runs up over the top of the valve & out the top outlet and into the hose. When it's moved up then it seals the top outlet and the flow runs below the valve to the main tap outlet. It shouldn't be very restrictive at all if it closes the flow properly up & down.

 

[sxturbo]

Be interested to see the outcome of this thread, I have the same style of bath tap and the flow through the tap is rubbish. Flow through the shower attachment is great though. Rest of the house oressurp and flow wise are exactly as they should.

 

[alex889]

What flow rates are you getting from this valve and others? Measure in lpm.
There are 000’s of valves out there and it’s either a poor one of them or problems lie elsewhere... impossible to tell without specific details or eye’s on.

I measured 20 seconds to fill a 2L bottle so that must be 6lpm. If I remove the tap cartridge and open the valve I get the 2L bottle filled in less than 8 seconds, so 15lpm? The flow is so restricted that if I raise the shower head to my height the flow drops even further, it feels like I lose about 30% flow. My hot water tank is at the same floor, my cold water tank is in the attic.

The rod on the lever moves the diverter valve up or down. When moved down then the valve seals the lower outlet, the flow then runs up over the top of the valve & out the top outlet and into the hose. When it's moved up then it seals the top outlet and the flow runs below the valve to the main tap outlet. It shouldn't be very restrictive at all if it closes the flow properly up & down.

The diverter moves and I can select between the tap or the shower head, but both have very low flow. If I bypass this diverter then the flow is fine. I can't see anything wrong with it but it could be that it doesn;t move the valve that much? I can turn the lever about 30 degrees, it seems it can't go any further. Maybe it should be moving further up and down

 

[Madrab]

If I bypass this diverter then the flow is fine.

How do you bypass the valve? It's integral to the tap. Or do you mean when the tap valves are out each flow is good before the diverter? That plastic diverter will actually pull out of the tap body, remove that and have a look at it check there's no restrictions. You may find it's the tap valves themselves not opening properly and a par of revivers may sort that. Was the tap fine before and has anything changed?

At the end of the day, how old is the tap and does it owe you anything? May be time to swap it out?

 

[alex889]

How do you bypass the valve? It's integral to the tap. Or do you mean when the tap valves are out each flow is good before the diverter? That plastic diverter will actually pull out of the tap body, remove that and have a look at it check there's no restrictions. You may find it's the tap valves themselves not opening properly and a par of revivers may sort that. Was the tap fine before and has anything changed?

At the end of the day, how old is the tap and does it owe you anything? May be time to swap it out?

I removed the cartridge and opened the valve before reaching the tap, the flow was fine. The plastic diverter barely move 2mm up or down and I can't take it out. I've force it to nearly the point it was going to break. I can;t see a proper gap to allow water to flow over or below that diverter.

The tap has always been bad, I've moved here 9 months ago. The house was built in 2005 but for some reason has these "classic" taps, definitely doesn't suit the style of the house.

What brands would be good value these days? I've read to stay away from B&Q and others as they tend to stock random brands that are just rebrands of low quality chinese stuff.

Are the taps sort of standard for the base? Mine seems to be 18cm between centres of the pile leading to the tap itself.

 

[alex889]

I think what I was referring to are tap legs. The problem that I can see now is access to the base of the tap legs is quite difficult.

https://www.toolstation.com/shop/p83848 these are similar to what I have

perhaps replace my tap with this https://www.toolstation.com/shop/Taps+&+Showers/d240/Bathroom+Taps+&+Mixers/sd2691

 

[Hot&Cold]

Plenty of room to get to the tap connectors,just take's a little longer

cant really see which existing tap you have,usually for showering the tap will have thermostatic control but you may already have balanced pressure/thermostatic control on the supply to the bathroom. Thermostatic control improves safety.

so many different makes of taps on the internet,dont be fooled by English sounding named manufactures/products they will be imported.Look for brands like Bristan and Mira. For a thermostatic bath shower mixer expect to pay £200+
180mm is standard uk bath tap connection centres

 

[Madrab]

Is your tap similar to one of these?

If so you can probably leave the pillars intact if they're clean and buy any wall/pillar mounted bath thermo filler/shower that has 150mm centres. Just check and measure the distance between the centres of the pillars where they connect to the actual tap body at the back of the tap valves, it'll hopefully be 150mm.

As @Old&Cold mentions though, thats a normal space underneath that bath for the pipework and tap connectors, so no issue to get to them, only issue is it's copper and if the pipes are well supported they may be difficult to move off the ends of the pillars if the nuts are tight. There is a knack to it all that comes with experience.

 

[alex889]

I don;t think I have any thermostatic control anywhere, you can get piping hot water on the tap.

I think I have low pressure or these taps are just too restrictive. Removing the tap I get high flow rate, putting a new tap in place to check has similar flow to the previous tap.

Perhaps that is the problem with a water tank, I can't really get much pressure.

 

[alex889]

Plenty of room to get to the tap connectors,just take's a little longer

cant really see which existing tap you have,usually for showering the tap will have thermostatic control but you may already have balanced pressure/thermostatic control on the supply to the bathroom. Thermostatic control improves safety.

so many different makes of taps on the internet,dont be fooled by English sounding named manufactures/products they will be imported.Look for brands like Bristan and Mira. For a thermostatic bath shower mixer expect to pay £200+
180mm is standard uk bath tap connection centres

Yep, standard 180mm indeed, just got one tap of the shelf to use and test, but not much luck

Is your tap similar to one of these?

If so you can probably leave the pillars intact if they're clean and buy any wall/pillar mounted bath thermo filler/shower that has 150mm centres. Just check and measure the distance between the centres of the pillars where they connect to the actual tap body at the back of the tap valves, it'll hopefully be 150mm.

As @Old&Cold mentions though, thats a normal space underneath that bath for the pipework and tap connectors, so no issue to get to them, only issue is it's copper and if the pipes are well supported they may be difficult to move off the ends of the pillars if the nuts are tight. There is a knack to it all that comes with experience.

Mine is very similar just shorted legs, half length

 

[Madrab]

Yup, you have great flow (22mm pipes) but lousy pressure (gravity) and such is life with gravity and the newer narrower waterways in modern taps. All you can do is get a low pressure/high flow taps to suit and live with it or pump the feeds.

 

[alex889]

I was looking for low pressure/high flow taps but they have like 10lpm at 0.2bar which I believe is likely to be my pressure. 10lpm is not that far from 8lmp that I measured as it is.

The problem I've see is that is you leave the shower head at foot level you get one flow rate, at your head level the flow decreases further 20-30%

Do you know any bath tap that would be close to the 22mm diamater?

I'm looking for taps but they don;t give any information about internals like diameters. Very frustrating.

 

[alex889]

I've found some examples here

https://www.drench.co.uk/vellamo-flare-bath-shower-mixer-tap

Flow Rates:

• Flow rate at 0.2 bar - 11 li/min
• Flow rate at 0.5 bar - 17.2 li/min
• Flow rate at 1 bar - 24 li/min

It seems the only way would be to have a combi boiler to replace my tank or then have some sort of pump for hot and cold water.

Do you guys have any suggestions?