Low Pressure from Surrey Flange to Power Shower

BABYCAKES · 19 Nov 2006

Hi there

I have a power shower fitted and it has been working fine for many months.

A few weeks ago there was poor flow of hot water. I was advised to change the Aqualisa grey cartridge, which unfortunately did not fix the problem.

I was then advised to change the twin impeller pump, which I replaced with an identical Wickes unit. This did not fix the problem.

I then switched off the pump and disconnected the inlet pipes. I noticed that the flow of hot water was much lower than the flow of cold water. I checked that the pipework from the hot water cylinder to the pump inlet was not blocked (i blew through the pipework!). Could the surrey/warix flange be causing the problem? Hot water to the rest of the house is fine.

Many Thanks

Softus · 19 Nov 2006

BABYCAKES said:
I checked that the pipework from the hot water cylinder to the pump inlet was not blocked (i blew through the pipework!).

Good information in your post. However I doubt that you could assess the potential flow rate by blowing through the pipe.

Could the surrey/warix flange be causing the problem?

This rarely happens, but can happen - you'll need to remove the flange to find out.

As an experiment, if you swap the connections on the Surrey, is the hot flow through the pump acceptable?

BABYCAKES · 20 Nov 2006

Thank you for your reply Softus

Am I right in saying that the hot and cold flows to the pump should be similar even though the hot water is coming through the surrey flange? My hot flow was significantly lower than the cold flow.

Swapping the pipes over for the hot water and the shower is going to be tough as they are at right angles and 22mm for hot water and 15mm for the shower feed.

Is it possible that the replacement aqualisa cartridge was also faulty? The one I removed looked clean and was intact.

Is it possible that air in the pipework is causing the problem?

I am at a loss as to what to do now...

Softus · 21 Nov 2006

BABYCAKES said:
Am I right in saying that the hot and cold flows to the pump should be similar even though the hot water is coming through the surrey flange?

Yes, correct. The hot flow is bound to be less because it's passing through more fittings pipework, but the aim should be to make the difference as small as possible.

My hot flow was significantly lower than the cold flow.

So you said.

Swapping the pipes over for the hot water and the shower is going to be tough as they are at right angles and 22mm for hot water and 15mm for the shower feed.

I don't know what you mean by shower feed, but temporary pipework is an ideal application for some plastic pipe and pushfit fittings. This was only a suggestion though.

Is it possible that the replacement aqualisa cartridge was also faulty?

Hang on - you said that the flows into the pump were significantly different, so where does the shower cartridge come into the equation?

Is it possible that air in the pipework is causing the problem?

Unless you've drained the cylinder that seems unlikely, because you said you have a Surrey/Warix flange.

I am at a loss as to what to do now...

May I suggest an objective measurement of the flow from various hot and cold pipes, as follows?

1. Cold feed into cylinder (if necessary, add a gate valve at a point higher than the tee off to vent and hot service).
2. Hot service from cylinder.
3. Shower outlet from Surrey flange.
4. Cold inlet to pump.

If you get significant differences, then investigate as you think appropriate.

If there are no differences, then do the same with the shower pump outlets, and compare those.

BABYCAKES · 23 Nov 2006

Once again Softus, thank you for your reply.

I have tested the system again:

With the Aqualisa cartridge out and the pump on - cold gushes out, hot has a slow flow

At the inlet to the pump - cold flow about 4 times greater than hot flow.

At the surrey flange - hot flow to shower is slower than hot flow to taps

Cold flow into hot cylinder is same as cold from from cold tank.

This indicates to me that the Surrey flange has a problem. Could a piece of debris have lodged itself in the flange? I am going to try and poke a stiff wire down to see if that helps. If that fails then I will remove it and inspect.

joe-90 · 23 Nov 2006

From reading this forum over the past year or so, the general concensus is that the Surrey flange is a poorly designed piece of kit that rarely if ever works properly. The reason being that the flow through the flange is poor due to the size of the apperture.

What type of flange did the manufacturer recommend?

BABYCAKES · 23 Nov 2006

Dear Joe-90

The thing that I fail to understand is that the power shower worked and then one day stopped working. Investigation suggests that the flange is at fault - could some debris have found its way into it?

I cannot imagine it has failed looking at this picture of a surrey flange:

I cannot see any mention of surrey flanges on the aqualisa websites and I was not aware that there were different manufacturers of them.

I will dismantle it when I get the opportunity.

Softus · 24 Nov 2006

BABYCAKES said:
The thing that I fail to understand is that the power shower worked and then one day stopped working.

That's exactly how all fault symptoms appear - one moment they're not there, the next they are.

Investigation suggests that the flange is at fault - could some debris have found its way into it?

Quite possibly. Why not just leave it in place and fit an Essex flange?

I cannot imagine it has failed

It's the nature of the universe that everything is capable of failing.

BABYCAKES · 24 Nov 2006

Softus - you are right and everything does fail.

Looking at the diagram above, the plug between the shower feed may be faulty or as I said it may be blocked.

Watch this space. I will report back as soon as I have delved deeper.

I appreciate your help and comments.

Nige F · 24 Nov 2006

Just a thought .......has the immersion heater been changed in the last few months .....it`s been known for particles of the foam lagging to get from the o/s of the cylinder to the inside

ChrisR · 24 Nov 2006

If it's recent Surrey it'll have 4 holes round the dip pipe, which will be drawn to a point at the lower end. Don't see how one would block easily.
I just put one on a tank which was feeding a wickes cheap pump.
With the pump off, and only about a 1 metre head, there was almost no hot flow but plenty of cold, so the flange and pipe resistance must have been significant. Once the pump was on though, no issue at all.

What hot flow do you get with the pump on - ideally measured before it goes into the mixer?
You could try the garden hose up the hot pie - you might be lucky!

BABYCAKES · 26 Nov 2006

Thanks everyone. It was debris in the dip tube that was impeding the flow of water.

Pressure is great now.

I love you all.

Babycakes.

xx

Nige F · 26 Nov 2006

Nige F said:
Just a thought .......has the immersion heater been changed in the last few months .....it`s been known for particles of the foam lagging to get from the o/s of the cylinder to the inside

OR it could be debris in the dip tube

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Low Pressure from Surrey Flange to Power Shower

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