Shower pressure problems – pump + essex flange still no luck

[BBunter]

Hi, this is my first post and I am hoping someone can give me some advice.

I have just finished installing my power shower system.

It comprises of the following :

Manual mixer concealed in wall will 15mm pipes running to the base of the bath.
22mm pipe running from the bottom of the bath approximately 3m to the airing cupboard.

In the airing cupboard the hot water tank and pump are located.

The hot water tank feeds a Salamander Shower Twin Pump 3.0bar RSP 100 via an essex flange for the hot (less than .5 meters in 22mm) and a dedicated cold supply via 22mm from the cold water tank in the loft (approx 1.5 meter above and 1.5 meters away)

The pump has been primed and water supply looks good on both the hot and cold sides.

However when I turn the pump on the pressure and water flow are disappointing at the shower.

I have good pressure on the hot water tap in the bathroom so I am starting to think I have a cheap/rubbish mixer unit?

I am going to see what the pressure/flow is like at the base of the bath and if its ok I guess the only solution is to rip out the mixer and replace it.

Anyone else see any problems with my setup above or something else I can try?

Thanks

 

[_luke]

As some others on here have found - have a look at the shower head and see if there is any kind of pressure-reducing device in there - sometimes just a bung with a very small hole in it.

Run the mixer with the shower head (not hose!) disconnected and see what the flow is like - with that pump you should have to hold on to the end of the hose - water should flow very quickly.

 

[BBunter]

As some others on here have found - have a look at the shower head and see if there is any kind of pressure-reducing device in there - sometimes just a bung with a very small hole in it.

Run the mixer with the shower head (not hose!) disconnected and see what the flow is like - with that pump you should have to hold on to the end of the hose - water should flow very quickly.

Thanks for the quick reply.

I did try it without the shower head attached and the flow was ok on full cold but it when I turned the mixer to full hot the flow was so poor the pump turned off....

 

[Richard C]

With a positive head salamander, you must have at least 600m from the underside of the CWS tank to the shower head (or any over & over pipe loops) or you are in a potential negative head situation. Check the water flow at the shower head, you should have at least 1 litre/min hot & cold under gravity (pump switched off) or the flow switches won’t kick in & start the pump; check the pump is actually running! Check mixer is correctly installed as suggested.

Other factors;
It’s best to run new, 22mm, right up to the mixer but you can drop down to 15mm from there to the shower head. Make sure that any isolator valves in the water feed & pumped lines are full flow, full bore (lever valves); most cheap gate valves will restrict the flow considerably. Long horizontal runs don’t help along with elbows rather than bends & torturous bendy pipe runs but a 3 bar Sally should easily cope with what you have. Is the pumped delivery pipe work new or have you just teed into some 22mm bath supplies that have been sitting there for the last 20 odd years? In which case it could be well furred up.

 

[BBunter]

Well I decided to take a feed from where the pipes arrive under the bath (before they go up in to the wall) and just run it in to the bath tub itself with two push fit valves in place.

WOW!

Had a hand from someone else and opened the valves at the same time and the amount of water and pressure took us both by surprise....

It was almost like both were under mains pressure...the pump was running not problems and was really pushing some water though the pipes.

I guess this leads to only one conclusion....the mixer itself is rubbish.

I notices I could unscrew the front of the mixer and take a look inside...pics of what I found are attached.

The first pic is the mixer without the cartridge installed.

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• BBunter
• 2 Feb 2010
• 1

The second is the cartridge.

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• BBunter
• 2 Feb 2010
• 1

The third is the cartridge fully closed.

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• BBunter
• 2 Feb 2010
• 1

The fourth is the cartridge full open.

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• BBunter
• 2 Feb 2010
• 1

As you can see from the fourth the gap the water is expected to go though is tiny and its no wonder the flow and pressure was poor.

So...does anyone have any recommendations for a mixer to surface mount or behind the wall (only have around 4cm in the wall).

Something that will be well suited to my pump and Deva KITROSE1 I am planning to install.....???

Any advice welcome

Mike

 

[leshill1]

Hi there,

I had the same issue as you with a Mira mixer shower and when i pulled it apart I had the same parts as those you have put pictures up of. I found that limescale had blocked the flow of water and having bought a new insert and installed it the presure was then fine. The insert cost me £10.00 from ebay and it's been working ever since.


Les.

 

[BBunter]

thanks for the reply.

it was some time ago. in the end I went with a Mira mixer which allowed allot more flow than the original.... problem solved