Low shower water pressure

[LittleJoe]

I am installing a wetroom in our en-suite bathroom and I have replaced the old aqualisa shower with a 0.1 Bar thermostatic mixer valve (22 mm connections, Hot in, Cold in and mixed out). It is feeding a 0.1 Bar low pressure 'drench'shower head.
The old shower was plumbed with 15mm piping so I have retained these runs of pipe and just used reducers to connect to the mixer valve within 8 inches of the valve.

The cold feed comes direct from the loft water tank with an 8 foot length of 15mm pipe that then drops down through the ceiling into the shower cubicle.It has a couple of 90 degree bends before connecting to the mixer valve. There is an old Gate Valve (with red knob) where the 15mm pipe just comes out of the loft water storage tank. There is a 4 foot head of water from the bottom of this tank to the shower head.

The 15mm hot feed comes under the floor via the 22mm pipe that feeds the bath but reducers to 15mm about 6 feet before it reaches the mixer valve. There are 4 X 90 degree bends in this pipe.

Both the hot and cold water pressures are poor. The cold is worse than the hot. If I turn the mixer valve to fully cold the water dribbles out of the shower head. When the valve is turned to hot, the pressure is just about acceptable but poor. In the mixer valve mid point, the pressure is about the same as when set to hot.

If I remove the shower head and monitor the water flow directly out of the wall plate elbow, it is pretty poor, ie. water projects about 1.5 to 2 inches from the pipe.

The hot water pressure has never been brilliant at any of the hot taps in the house except for the bath. The main bathroom shower is plumbed completely with 22mm piping and uses the exactly the same mixer valve as I am using in the en-suite, although it uses a different 0.1 Bar shower rose, and it also suffered with the same low water pressure problem. I fitted a pump to solve this shower pressure problem. I really don't want to fit another pump for the en-suite. I feel that with 4 foot of water head, I ought to be getting enough pressure.

Before I progress any further I thought I would post this problem to see if anyone has any suggestions.

I am suspicious of the gate valve in the cold feed, possible blockages in the 15mm feed, debris in the mixer valve.

Any suggestions welcome at this stage.

Regards

 

[seco services]

start at the beginning.
your static height is only about 1m - not enough for a descent shower
shower should have it's own supply from tank / cylinder not teed of the bath supply.
reducing to 15mm is no good should be kept in 22mm all the way as you say your mixer takes 22mm.

long term fit a pump.

 

[LittleJoe]

Thanks Seco Services.
Plumbing a seperate 22mm supply from the Hot water cylinder is really not practical in my house (a major job!!!). I guess I could look at raising the cold water storage tank in the loft. How much higher would you suggest to make the presssure acceptable?

I can change the 15mm piping to 22mm.

A pump can be fitted as a long term solution, it's just the noise, and it would have to be located in my sons built-in bedroom wardrobe behind the shower wall.

Regards

 

[seco services]

raising tank don't give much 1m will only give 0.1bar every m.
and you need to try and balance the flows as you say your hot is good cold is poor so your mixer may always be slightly turned to the cold side to get a even shower temp.

but a pump will sort that out.

 

[LittleJoe]

Thanks.

I am going to replace all 15mm with 22mm and remove all 90 degree bends wherever possible using a pipe bender instead. I will replace the gate valve with a ball isolator valve.

I will see how things work then. I really want to avoid fitting a pump if at all possible.

Thanks again.

Regards

 

[seco services]

don't fit any ball-o-fix or any valves that restrict flow.
use full bore isolation valves or you'll be back to square one.

 

[LittleJoe]

Good point. I will ensure I use full bore.

Thanks