Bath shower mixer...increase back pressure to keep diverter up

[Mark Huddleston]

I have a gravity fed system and have recently fitted a bath shower mixer tap designed to work at low pressure (0.2 bar). Granted the diverter knob will stay up most of the time but it’s bit hitty missy. Am I right in thinking that if I get a smaller bore hose it will provide more back pressure and keep the knob up? I have seen various diameter hoses but confused as to whether I need a smaller or larger bore hose. I’ve also seen shower heads designed for low pressure systems. Has anyone any ideas?

 

[Welder]

It's not back pressure that keeps it up but the pressure in the supply. By reducing the bore all you will do is reduce the flow.

I'm afraid no spring operated diverter is suitable for your (I'm guessing) low pressure system.

FYI there is NO consensus on what 'low pressure' means. This has been a bone of contention in the UK plumbing industry for decades. Manufacturers 'sell' something as low pressure simply because they want to move product. As it nearly all originates from across the globe where they universally use mains pressure for everything (so 3-5 bar) low pressure is strictly something like 0.5bar. Unfortunately the UK's low pressure is more like 0.1bar. Hence them not working as advertised.

 

[Mark Huddleston]

It's not back pressure that keeps it up but the pressure in the supply. By reducing the bore all you will do is reduce the flow.

I'm afraid no spring operated diverter is suitable for your (I'm guessing) low pressure system.

FYI there is NO consensus on what 'low pressure' means. This has been a bone of contention in the UK plumbing industry for decades. Manufacturers 'sell' something as low pressure simply because they want to move product. As it nearly all originates from across the globe where they universally use mains pressure for everything (so 3-5 bar) low pressure is strictly something like 0.5bar. Unfortunately the UK's low pressure is more like 0.1bar. Hence them not working as advertised.

OK cheers. If it’s all based on the pressure in the supply how come the diverter doesn’t stay up when the hose is disconnected altogether? When I take the hose off and try it the knob just gets pulled straight back down.

 

[Welder]

It uses the flow to keep it open. Flow is a consequence of pressure & bore. Your pressure simply isn't high enough and you cannot increase it unless to add a pump to the system.

 

[Ben-gee]

If it’s one where you pull up the knob and a spring pushes it back down; I have overcome this problem in the past by cutting part of the spring away.
Do this little by little until it works, as you can’t add it back on again.

 

[Welder]

If it’s one where you pull up the knob and a spring pushes it back down; I have overcome this problem in the past by cutting part of the spring away.
Do this little by little until it works, as you can’t add it back on again.

Part of the reason for a minimum spring pressure Ben is to guard against cross contamination. Personally I'd not recommend that course of action on an open forum.

 

[Mark Huddleston]

I’ve already found that reducing the 2m hose to a 1.5m length has made it work better

 

[Sharp Point]

I’ve already found that reducing the 2m hose to a 1.5m length has made it work better

Put a 0.5m hose on then, for total amazingness