Mega flo again.

19 Jun 2017
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United Kingdom
Hi All.

Does not matter what ever i google for advise and help on a Megaflo all the good advise comes back to this forum! Looks like this is the place that you pros hang out too!

I am not a plumber so hope I'm welcome and to be honest most of my trouble shooting has come from here too.

So hopefully you guys may be able to put me out of my misery!

First point to note I have had 3 different plumbers out that are all G3 (i think thats right?) to use unvented systems.

So far not a great deal of progress, the reason for 3 different ones is 2nd and then 3rd opinion.
Of which none have come back with the same answers, hence reaching out on here.

So the problem you ask:

We have been in our new house for 3 years and over the last 6 months the showers have got weaker and weaker, the house is quite big (lucky me) 3 stories with 2 bathrooms and 1 ensuite. All the showers are either 20cm rain heads or bigger (sorry forgot the brand) and have until recently been great.

Now they are weak and i would say about 50% that of what they used to be.

The information I have:

The water board came and tested the supply in the road outside my house and said its 3 bar

Bought a pressure gauge and checked it on the outside tap (its in my garage actually on the same run as the main stop tap. It shows 2.5 bar.

The house is only 7 years old and i can see the pipes coming in to the stop tap are blue plastic and quite big - I'm guessing 28mm

Pipes going up to i assume the Megaflo are copper and again I'm guessing 28mm

Megaflo is on the 3rd floor next to our ensuite:

Had the Megaflo bubble reset about 3 times.

The last plumber fitted a gauge on the incoming cold water next to the Megaflo and it now shows 2 bar.

He also fitted a gauge on the top of the mega flo and that says 2.5 (no more)

1st Question:

Is the Megaflo correct at 2.5 as i thought it was to be at 3.0 bar, I assume as the incoming gauge next to it is 2 then thats why?

He also fitted a completely new valve, i think is a PRV (learnt that on here!) but it is different from the original as its a multi bloc - has the PRV and the 8 bar relief combined on it.

But i have noticed there is a blue plastic ring on the collar and it says 2.1 bar

I have looked on line and i think it is this:

"2.1 bar Reduction/8 bar Relief - 1 Piece Multibloc Inlet Control Valve" (RELIANCE)

2nd Question:

Should it not be a 3 bar PRV? as i assume that it does what it says on the tin and is reducing / balancing it to a maximum of 2.1 bar. I know that sounds silly but I'm just looking for clarification.

The One he took of was a 3 bar as again it says it on it (on the black cartridge)

Surly having a 2.1 bar is not the correct valve?

Time for my guessing and confirm what has been done to date:

All shower heads taken off and cleaned ran water with no heads on and still quite slow.
Re setting the bubble correct:
Noticed after resetting the bubble that the kitchen taps did not work at all, Cleaned the filter out (the ones that unscrew on the ends) and it was full of crud.
I assume that is from the bottom of the Megaflo when draining it?

Fitting gauges correct:
Changing the PRV (although i know the original can be cleaned i was happy for him to replace it for a whole new one just to rule that out) - but swapping a 3.0 bar to a 2.1 bar?

He said thats what they had in stock at the suppliers:, I only noticed the 2.1 bar after the event and it was fitted.

So my issues:

Since the new 2.1 bar valve was fitted the showers have got even worse:

I am still no better and closer to any improvement:

What I'm hoping for:

To get back to where we where (or better) 6 moths ago. Unfortunately we did not have any gauges until after we noticed the big drop so can not comment on what it was.
But can say hand on heart that the showers are 50% of what they used to be. Without even saying anything both my wife and children have pointed out how bad they are:

Moving on:

I am at the thought that maybe we just do not have enough pressure coming in anymore, maybe we used to have a lot more and the 3 bar valve we had was doing just fine, maybe united utilities have reduced it to our post code as my neighbours is roughly the same on there outside tap (slightly more if I'm honest 2.8 bar - oh i wish i had that!) I guess outside tap is always the best.

Whats next?

Replace the 2.1 bar valve to a new 3 bar?


I have read and read everything i can find with obviously some conflicting options.

I think it time to look at a way of getting more pressure to the mega flo? Or is that not the case?

The megaflo as mentioned is on the 3rd floor and we do have a loft space above the room its in if that helps at all?

I have read about:

Accumulators, Pump Sets and Water Boosters.

This is where i get completely lost and hopefully this thread can be one that we get a result from.

Should i get yet another plumber? Or ask the last One to swap the 2.1 bar?

If that was a mistake he has made then should i continue with him / if / should he swap it?

He is a really nice guy and seemed to talk the talk but i cant afford to continue with him if that was mistake with the 2.1 bar valve.

Or am i left with once again trying to find another (obviously G3)?

I really just want powerful showers again! and too have a plumber that can advise / fit the right solution be it a Accumulators, Pump Sets and Water Boosters or not.

So if anybody is super star and wants to have a go, Im in Bolton! BL7

I would love some good advise and would like to keep this thread going until the job is done so it can be of use to anybody else in the future.

The problem with forums is once somebody has the info / options / advise they need then they never bother to share the solution as they are all fixed and thats rather selfish.

I would like to leave a solution here and will update it with what was done.

Many thanks in advance and I look forward to hearing your wise words.
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Get the valve changed for a 3bar for a start, when you are checking pressure do you have a tap running ? with the water running you measure residual pressure rather than static pressure, double check that all stopcocks are fully open, come back when done and we can go from there.
Your shower valves will have filters on the inlets. As your kitchen tap proved, some crud has been stirred up. First clean these filters. You may have to clean them twice. Picture of shower may help us to tell you where the filters are.
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Hi all.

Thank you so much for the replies!

"when you are checking pressure do you have a tap running"

I did not, but have now tested it with a hot tap on in the ensuite which is in the room next to the Megaflo = 1.5 Bar on the megaflo gauge.

"Your shower valves will have filters on the inlets"

I suspect the shower filters on the inlets, are yes buried behind tiles as there is no pipe work on show what so ever just the controls - ON / OFF / temp etc.

"double check that all stopcocks are fully open"

As far as I am aware there is only the One in the garage and the one below the 2.5 BAR PRV again next to the megaflo = All fully open.

"New House May have limescale reducer fitted under Kitchen Sink"

Not that i can see , the only thing that is not the norm are some bits i assume for the boiler (Boiling water on demand) But no filters.


I have tried to order a 3 bar cartridge to change out the 2.5 but they only sell them as full unit, so thats on order, will have that Thursday and I have taken one out before to clean so am confident enough to take the 3 bar one of the new one and swap it for the existing 2.5 bar cartridge, I assume you can swap the cartridges as the unit is obviously fitted and don't see the point in swapping the whole thing if it just the 3 bar i need. I am a bit annoyed that the last plumber even put that on.

United utilities are coming out Friday, but to be honest out this will do anything apart from confirm what they are supplying to the house and if I am on a shared supply etc.

I have done as much research as i can possibly digest without getting lost, so am stopping trying to find a solution on my own.

I guess i will haves to see if the 3 bar replacement does anything, but i do suspect it will only add a margin.

Happy to try any other suggestions, while waiting for the 3 bar part.

Im just hopeful that this thread will be a great resource from start to end with the end being a RESULT.

I know I'm going to have to spend money to get this right and accept that.

End goal: Is this to much to ask?

The incoming water feed gauge on the 3rd floor next to the megaflo to be at 3 bar minimum - ( residual pressure) its now 1.75

Megaflo gauge to be at 3 bar (residual pressure) its now at 1.5

This should in my thinking provide enough power to get the showers back to where they where 6 months ago?

The last few weeks have just been a right stress of which i am reminded of every morning when i stand under the once super powerful rain shower, getting more annoyed every day.

Finally i would like to say how much i genuinely appreciate all the comments so far and for anyone taking a genuine interest, it does give me a lot of confidence that we will get this working.

I was thinking about doing a full write up after the event with pictures etc, maybe a kind of guide - trouble shooting that ends with a great solution!

Thanks again.

What is the pressure out of the hot taps like? I would be looking at debris in the inlet filters as previously mentioned.
The hot tap pressure is not great at all. But better once a took of the little filter on the end of the tap (just the one that unscrews)

Im not sure how you access "inlet filters as previously mentioned"? On the showers or the taps
Your pressure is terrible, wait till your cartridge is changed before doing any thing else or you might introduce another fault .
Your pressure is terrible, wait till your cartridge is changed before doing any thing else or you might introduce another fault .
That is exactly what i was thinking.. Ill update the thread Thursday , thanks guys

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