gravity fed shower problems

[neilinbal]

i have recently moved a thermostatic shower from one side of a bathroom to the other. This always worked well before. I've fitted a triton thermostatic mixer valve works off 0.5bar which is directly under the tank in the loft. i have about a metre head. the problem is the shower works for a few days or weeks then the pressure goes. if i hold the shower head down then alls well but as i raise it up no pressure.
The hot is piped from the expansion going into the loft tank, just below the bottom of the tank. I guess i'm asking if i re pipe it lower down will it help?? or is it a completely different problem. i am stumped, completely clueless so any help please. thanks
Also there is another shower on the wall directly behind this one the hot comes up from the hot water cylinder straight into the shower. this work really well.

 

[Charnwood]

1 metre equals 0.1 bar, your shower needs 0.5 bar. Nuff said.

Lowering the showerhead will increase the head of water/pressure, but not noticeably, and will render the shower useless - unless you want to shower sitting on the shower floor.
Is t'other shower ecactly the same; make, model, specs?

Raise the tank or fit a pump.

 

[neilinbal]

hi cheers for answer. other shower is a mira. sorry i said it was 0.5bar it's min pressure is actually 0.1 bar.
Why will it work for a while then stop??
is the hot water piped ok coming from what i think is the expansion pipe??
Will re piping not make any difference??
Thanks, it's just i don't understand why it worked for god knows how many years but stopped when i moved it 6 foot closer to the tank.
cheers again

 

[Charnwood]

As it was working OK previously it might be blocked filters, scaled pipe.

What do you mean by repiping? the head is and always will be the vertical distance between the header tank and the showerhead, no matter how far the lowest bit of pipe is.

When you say 'expansion pipe' presumably you mean the pipe coming from the connection at the top of the cylinder. If so, yes, it's correct.

You say you moved it 6' closer. Horizontally? Did you just add 6' of pipe? Any extra elbows? Can you repipe it via a more direct route?

 

[neilinbal]

cheers again
when i say expansion i mean the 22mm pipe that comes up & over the cold water tank. When i moved the shower it came 6 feet closer horizontally, so just shortened the pipe work & upgraded as much as i could to 22mm, no extra bends or elbows as it was all in 15 before. I just wondered if piping it up lower down like the other shower would make any difference.
I have had to clean filters before & works for a while but when i take it apart i can't see much in the line of debris. I shouldn't have to do this every month or so though should i??
Thanks again

 

[Charnwood]

Is it 22mm all the way from the tank to the mixer (cold) and tank to cylinder to mixer (hot) ?

Lowering pipework, but leaving the tank and showerhead in the same place will do nothing for the head, as I stated previously. Once the water starts to go uphill the head decreases again. The perpendicular height determines the head.
View media item 62825

 

[longdogs]

Are there any 'high points' in the new pipe run ; ie: does any of the pipe run uphill then downhill? Air can get trapped in a high point.

 

[neilinbal]

Thanks again guys. Right the pipework is 22mm from copper cyl downstairs then t in loft where 22 carries on over tank & 15 then horizontal 2ft then vertical in 22 for 5ft. Cold in 15 from tank 2ft then vertical 5ft all in 15. No high points no weird runs. Have cleaned it out & a bit better but will eventually end up a trickle again. Do you think it could be air???

 

[Charnwood]

then t in loft where 22 carries on over tank

OVER the tank. I thought you said no high points. And that defies gravity. Water finds its own level. How on earth have you got it leapfrogging the tank?

 

[neilinbal]

Sorry think I'm confusing you. It tees off below the tank. But the 22 carries on to loop into the tank which is what I mean by the expansion pipe. That's what I've been told that the expansion pipe rises into the loft & back into the cold tank. Well that's where the shower tees off from right under the tank in15mm does thus make more sense? Sorry if its abut confusing

 

[Charnwood]

Sorry think I'm confusing you.

You think? I know:

where 22 carries on over tank & 15 then horizontal 2ft

 

[neilinbal]

Well what is that pipe that just hangs over the cold tank called?? Because its tee'd off that but bellow tank level. That's the hot. Cold off tank as normal then drops to shower valve. That's about it really.
Cheers. That's the non confusing version

 

[Charnwood]

This is the non-confusing version - hopefully.
Not to scale, not fully plumbed in, but is this your setup?
View media item 62835

 

[neilinbal]

exactly that yes

 

[Charnwood]

That drop to the ground floor to the cylinder will not help your cause.

A to B is about 1 metre?
View media item 62838
Pump.