Loss of shower pressure

[Richard210363]

Hi there,
Since I had some work done I've lost pressure in my shower.

I have a downstairs bathroom and ran a shower off of a mixer tap. Being on the ground floor I had good cold water pressure from the tank in the loft.
Mixing in the hot from the hot water tank (also on the ground floor) I got a reasonable head of pressure in the shower at a reasonable temperature.

Recently, I had a plumber (a mate) add inline valves to the supply so that as I decorated the bathroom I could isolate the taps as I moved the sink and bath around to plaster and decorate behind them.
He also added a 15mm spur off the pipe work as I was undecided as to where the sink would end up after the redesign

Now I find I have a much reduced pressure to the shower and taps.

Could it be because he reduced the pipe work from 22mm to 15mm to incorporate the valves?

I have 15mm flexible hose connecting the new mixer tap/shower to the old pipe work. I wondered if the hoses absorb the pressure as they flex but I also get reduced pressure from the new 15mm spurs.

I have checked and I believe that all valves in the system are fully open.

What can I do/test to solve this problem?

Thanks for any advice.

 

[seco services]

should of used 22mm full bore isolation valves.

 

[Richard210363]

So the reduction in size will lower the pressure?
So all I need to do is make sure the pipe work is 22mm all the way?

 

[Richard210363]

I've found the formula for water resistance here and going from 22mm to 15mm reduces the water flow to a fifth of the original!!

I'll make the changes

 

[seco services]

So all I need to do is make sure the pipe work is 22mm all the way?

i would.

 

[Richard210363]

Cool. I'll let you know how I get on.

 

[Richard210363]

Hi Seco,
I've replaced the pipe work with 22mm and the flow has gone up considerably.
It is still not quite as it was.

I used to have a mixer tap with 2 valves and 2 handles.
When I turned them both on the subsequent water flow was all of the cold water flow plus all of the hot water flow.

Am I right in thinking that with my newer single lever mixer tap the water flow is constrained to either all cold, all hot or 50% of each at the central position? (and any other % combination).
My hot and cold pressures are approximately equal.

 

[Rico99]

Rich,

One more thing you may want to check, is if your tap/mixer is suitable for low pressure systems like yours.

Most modern 1/4 turn taps are only designed for high pressure systems like combis.

Rico

 

[Richard210363]

I didn't know that.

Bother!

I may have to fit a pump. Or buy a new older style tap