Low pressure issues with shower?

[zenonithus]

Hey guys,

I have a riser shower same as in this image. Lately the pressure has been pretty weak. Also the temperature is really up and down going from cold to very hot and back and fourth. I have ordered a replacement mixer bar that I hope will at least fix the temperature setting, though is it likely to fix the weak pressure? Does the mixer bar control this? I am also descaling the large shower head in vinigar though it looks as if it comes out the pipe fairly weak.

I just had the boiler checked over and all is working fine though could the pressure be a boiler issue? The flow from the taps isn't too bad though no way near as powerful as the cold water pressure.

Any help would be great. thanks

 

[terryplumb]

Remove the shower valve and check the filters,if they are clean, Whilst removed, turn water back on and establish the flow from the open pipe. You may need to cap the cold pipe and fit a full bore isolator to the hot pipe in order to carry out the flow test.

 

[zenonithus]

Hi Terry, thanks for the advice, that is a good point. So do you mean removing the mixer bar and testing the actual hot and cold feed pipes? I will try that thanks. Is there a way to read if the pressure is low when the water is flowing out the pipes?

 

[terryplumb]

Yes ,isolate water supplies and remove the mixer bar from the wall.
Pressure can only be established with a pressure gauge ,however ,the flow rate can be measured by timing over 1 minute ,how many litres of hot water runs from the pipe into a bucket. That would need you to be able to control the flow of water ,so you may have to do a temporary plumbing job on the two pipes that come out the wall . Capping the cold ,and fitting a full bore isolation valve to the hot. That will enable you to turn back on ,the water supplies.
Just watching the flow from the pipe will give you a good idea of what's being delivered ,pressure and flow wise.
Is your hot water from a combi boiler ??

 

[zenonithus]

Hey Terry, great thanks for the advice I'll try this out, should be easy enough to fit a temp isolation to check the flow. Yes this is coming from a combi boiler. When the shower pipes were installed and I fitted the shower the water was flowing out good so not sure if over time limescale has clogged up something in the mixer bar. Otherwise is it possible for the hot water pressure from the boiler to degrade over a couple of years?

 

[terryplumb]

Pressure from the boiler won't really change ,but the flow rate can. You said the boiler has been checked and is fine...???
Blocked filters in the boiler and in the shower valve itself are the first things to rule out .

 

[zenonithus]

Thanks Terry, yes the boiler had a full service last week and all seemed good. I'll check the pipe filters when the new mixer bar arrives tomorrow. I'm really hoping that a new thermostatic cartidge inside will fix the issues. Though still not sure if that controls the flow rate.

 

[terryplumb]

Let's say ,for arguments sake ,that the open pipe flow rate is ,9 litres per minute. The thermostatic valve and the pipe/ hose outlets will create a level of resistance to that flow ,and you should get somewhat less than 9 from shower heads.
If you only get 6 litres per minute from the open pipe ,then your problem is the supply ,not the shower.
Have you purchased a complete new shower ,or just the cartridge to replace in your existing shower ?

 

[zenonithus]

Good point. I'll see about doing a test with just copper pipe and then measure again once the shower is assembled so the flow out of the riser bar without the shower head attached. I do have a video of the water coming out of the riser bar without the showerhead and it looks quite slow. I'll see if I can upload it here. I purchased a whole new mixer bar with taps as I couldn't locate the exact cartridge from my current shower mixer bar. So doing a straight swap with the entire mixer tap bar.

 

[zenonithus]

Quick update on this. So as terry suggested the filters on the connecting water pipe fittings were clogged with limescale (I live in a very hard water area) and rust. So changed them out with new ones, though pressure was still low. I figured it was the diverter valve that as the lever is really stiff and I noticed nothing really moves inside when I move the lever so the lever isn't fully allowing the water to pass through. I am soaking it in vinegar to hopefully loosen up the limescale. Though might just buy a new one on ebay.

 

[terryplumb]

Did you measure the flow rate from open ended pipe ? If so what was it ?

 

[zenonithus]

hey Terry, I didn't get round to this as there are shower bar attachments fixed to the pipes so wanted to rule out any issues with the shower before removing those. Though I think the water pressure is fine as I attached the hand held shower hose end directly to the mixer bar top outlet and the difference was clear as the water shot out at a much more powerful rate.

 

[terryplumb]

Ok ,sounds like the showers diverter is duff as you suspect.