Gas fitter masquerading as a plumber.

[ShaunM81]

Gas fitter here needing some experienced plumbers advice.

A family member has had a new kitchen + bathroom fitted. The hot water coming from her gravity tank has a very poor flow rate now at all her taps, as does the cold mains, strangely. After checking the usual suspects - stopcock, water in tank etc I then attached a water pressure gauge to the cold mains pipe going to the kitchen sink and was getting 1.5 bar. Hot water was around 0.1 bar which is pretty normal I believe for each. Yet very poor flow rate coming thru the actual taps. I done the same checks in the bathroom sink + bath and same outcome. Toilet is filling fine and electric shower pressure is fine.

Is this due to the “wrong” kind of taps fitted? The old taps were all individual full turn types. Now theyre all mixer tap 1/4 turns. The ones in the bathroom are the waterfall type. Could these new tap choices be designed for a different pressure or could the 1-4 turn type be wrong in some way?

Any advice appreciated cheers.

 

[Gasmk1]

are they fitted on flex connections some of these are quite flow restrictiong also are there isolations valves if these are not full bore they also restrict flow

 

[Harvest Fields]

You are correct you can get low pressure taps. But as above check for kinks in flexi pipes

 

[Riley]

Waterfall style are notorious for low flow

 

[ShaunM81]

Yes onto flexi’s mate and have isolation valves, however the pressure after the isolation valve on the mains side is 1.5 bar, so I don’t think the iso valves are the issue, the pressure after each iso valve is fine as id disconnected and checked, so the only possible things are the flexi hoses and the taps themselves, the water is dramatically reduced coming out each tap for hot and cold, could it be a mixture of flexis and incorrect taps?

 

[Harvest Fields]

Possibly mate. What make and model of tap is it?

 

[Riley]

Do we know where they were purchased from also

 

[Pickwickpick]

I think its more likely that the taps are the main issue although flexis & iso are probably contributing. Could you try scrapping the flexi and iso valve (or swap it for full bore) on one of the taps? Also have they still got the original taps to hand? If so you could swap one of the new taps for an original one, connecting it to the flexi. This would be a fairly cheap and quick way to rule things out.

 

[ShaunM81]

Can’t see what brand the taps are unfortunately, and I don’t have the old taps

So when you say full bore taps, do you mean taps with 15mm straight into them?

 

[Riley]

Ask them where they bought them they could be off eBay. They could be some tat from vp

 

[rpm]

PTFE tape where flexi joins tap is half blocking the outlet in the flexi?
Have seen it.

 

[ShaunM81]

No ptfe or anything else present, 90% sure now it’s flexis and incorrect taps... for future reference do you guys match certain taps to specific water pressures? As in gravity water = low pressure compatible taps?

 

[JCplumb]

The waterfall tap I have on my bath has pre-fitted flow restrictors, I didn't take them out before fitting and I now regret it as the flow is awful.
One day I'll get the time to take the panel off and remove the buggers.
Maybe your waterfall tap has these too?

 

[ShaunM81]

The waterfall tap I have on my bath has pre-fitted flow restrictors, I didn't take them out before fitting and I now regret it as the flow is awful.
One day I'll get the time to take the panel off and remove the buggers.
Maybe your waterfall tap has these too?

I think you are spot on mate I will check for these too!

 

[Aire]

Have you checked the filters on the outlet? Kitchen mixer will probably have a high pressure filter on its outlet which clogs up easy and some of the waterfall taps I've came across have a mesh filter in the outlet too.

Could also be the tap isn't designed for low pressure systems, if you know the tap make and model, check the min specs online

 

[ShaunM81]

Brilliant thanks a million guys really appreciate it the replies.

Fantastic site

 

[Pickwickpick]

Can’t see what brand the taps are unfortunately, and I don’t have the old taps

So when you say full bore taps, do you mean taps with 15mm straight into them?

Full bore was in reference to the isolation valves, the standard ball-o-fix isolation valves are only about 8mm inside.

 

[ShaunM81]

Full bore was in reference to the isolation valves, the standard ball-o-fix isolation valves are only about 8mm inside.

Thank you mate

 

[gmartine]

Take out the tap aerators.

 

[Welder]

No ptfe or anything else present, 90% sure now it’s flexis and incorrect taps... for future reference do you guys match certain taps to specific water pressures? As in gravity water = low pressure compatible taps?

There is much nonsense talked about tap flow rates. There is no formal definition of low or high pressure so one manus hi is another's lo. It's literally a lottery. From what you say in your original post, NO 1/4 turn tap or single lever tap will give you even reasonable flow rates. You are better off converting 1/4 turn to traditional multiturn. Yes, it can be done.

What you are trying to achieve is flow rate i.e. how much water flows into the bowl in a set period. While pressure has an impact on that, its the dynamic pressure (i.e. when open) that is counts not the static pressure (when closed). The static will always be higher.

Flow rate, just like through a combi, is deeply affected by ANY and EVERY restriction. For a low pressure HW system like this one then you MUST use hard tap tails (can be bought seperately) and full bore iso valves. Check EVERY valve on the supply pipework cos ANY valve that is not full bore will utterly compromise flow. If you had 35mm pipework from the cylinder to the tap and a cheap iso with its 8mm hole then your pipework is effectively 8mm in dia. It's NOT the same as gas.

HTH

 

[Callumjb]

Have you tried seeing if there is an aerator on the end of the tap outlet. These often restrict flow and especially will affect gravity hot water

 

[dan_the_plumber]

You seem to have focused on pressure. Is this 1.5 bst static pressure or dynamic pressure?
Also I tend to find that what you shouldmainly focus on is flow rate, not pressure

 

[ShaunM81]

There is much nonsense talked about tap flow rates. There is no formal definition of low or high pressure so one manus hi is another's lo. It's literally a lottery. From what you say in your original post, NO 1/4 turn tap or single lever tap will give you even reasonable flow rates. You are better off converting 1/4 turn to traditional multiturn. Yes, it can be done.

What you are trying to achieve is flow rate i.e. how much water flows into the bowl in a set period. While pressure has an impact on that, its the dynamic pressure (i.e. when open) that is counts not the static pressure (when closed). The static will always be higher.

Flow rate, just like through a combi, is deeply affected by ANY and EVERY restriction. For a low pressure HW system like this one then you MUST use hard tap tails (can be bought seperately) and full bore iso valves. Check EVERY valve on the supply pipework cos ANY valve that is not full bore will utterly compromise flow. If you had 35mm pipework from the cylinder to the tap and a cheap iso with its 8mm hole then your pipework is effectively 8mm in dia. It's NOT the same as gas.

HTH

Brilliant thank you

 

[TMHM]

Just an aside here, but I got caught out buying a tap in France, where they use mains pressure hot and cold water, the flow rate out of the tap on the hot side was unusable when installed in the UK.

 

[ShaunM81]

Just an aside here, but I got caught out buying a tap in France, where they use mains pressure hot and cold water, the flow rate out of the tap on the hot side was unusable when installed in the UK.

Why couldn’t it be used exactly? Just curious

 

[TMHM]

Just that the flow rate was so bad and so different from the cold side. I assume that there must have been some form of prv, but why it affected only the hw side, I am not sure.