Mixer Shower and Gravity Fed System

[Toobrish]

About 10 years ago we had a new mixer shower fitted. However, the most we ever got out of it was a trickle - even from the beginning. At the time I looked up the manufacturers installation instructions and it says that the showerhead needs to be at least 1 m from the bottom of the water tank we have in the loft. At this point I thought that we had made a costly mistake and was annoyed with the plumber for not getting the job done properly. As a temporary measure, I fitted a shower hose over the bath taps and it has been working okay for all these years.

I’m now finally getting round to seeing if I can fix the built-in shower and a few things don’t make sense to me. Firstly the pressure doesn’t seem too bad. From the video below you can see that it seems reasonable. The outlet here is about 1.5 m from the underside of the water tank in the loft above.

View: https://youtu.be/kyxN3vqHYJM


Then when I fit on the mixer unit, I can only get a trickle as shown in the video below.

View: https://youtu.be/re0UISNxwoE


According to the manufacturers instructions, I think I should be getting much more flow than this. If anyone can give some advice I’d really appreciate it.

 

[Aquarius]

Check to see if the inlet filters are blocked. Check is it piped the correct way around? There’s obviously a restriction of sorts after you fit the valve. What model of Bristan is it?

 

[Toobrish]

Check to see if the inlet filters are blocked. Check is it piped the correct way around? There’s obviously a restriction of sorts after you fit the valve. What model of Bristan is it?

It’s a D CSHXRR C Bristan Art Deco Thermostatic Shower Kit . Not sure where the filters are. I am not seeing any.
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I should have said, my family are putting pressure on me to fix the shower ASAP - I just wish it was the shower which had the pressure not me

 

[Aquarius]

They should be on that elbow that you pointed at the wall. Also check both isolation valves are open and balanced supplies.

 

[Ben-gee]

You only show the right hand side flowing well- this should be the cold.

Is it possible this is the mains, and only the hot side is from the tank?

 

[Toobrish]

You only show the right hand side flowing well- this should be the cold.

Is it possible this is the mains, and only the hot side is from the tank?

Looking at it again - that is possible. But even if that's the case, shouldn't the flow be good when the shower is turned fully to cold. At the moment its poor no matter where the temperature controls are.

Today I took the shower into the garden and connected it to the mains via a hose. The flow was a bit better but far from adequate. It seems like the mixer cartridge is reducing the flow considerably. Is that normal?
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They should be on that elbow that you pointed at the wall. Also check both isolation valves are open and balanced supplies.

My father in law and I connected up the shower unit to the cold supply at mains pressure on both sides to make sure the supplies were balanced. As you can see in the following video, the flow is still poor....

View: https://youtu.be/EOJljVy6sME


Have tried to contact Bristan, but they are impossible to reach at the moment. Will keep trying.

Is this a faulty mixer? Are we missing something?

 

[Aquarius]

It could be the cartridge, but I doubt Bristan will accept it now. Whether you could get them out to look at it?

 

[Toobrish]

It could be the cartridge, but I doubt Bristan will accept it now. Whether you could get them out to look at it?

Good idea. I’ve filled it up with limescale remover to see if that helps in the meantime

 

[John.g]

Worth a go even though you say it has never worked from the beginning, I read somewhere that showers like that should flow ~ 9 LPM @ 2M head without the shower head attached so should have been belting it out at mains pressure, you might be able to disassemble it for a good inspection.
For interest attached is a good description of a competitor's thermostatic shower (page 24 onwards)