Poor pressure on a megaflo??

davecon1 · 6 May 2006

Help!

We recently had a 170 litre megaflo and a valiant boiler installed into out 3 bedroom house in preparation for a loft conversion. After a few teething problems things seemed to be OK and we had great water pressure.

Now the loft conversion is complete the water pressure upstairs seems to be much less than downstairs. Also if you run the bath on the 1st floor (the boiler is on the first floor) or run the tap in the kitchen you can visibly see the pressure decrease and the shower sometimes starts to 'throb'.

Can anyone please offer me some advice on what might be the problem? My plumber is saying this is normal as the water is being diverted and HeatraeSadia say that as my flow rate is 20 litres per minute this is the minimum they recommend for their system. I was under the impression that Megaflos are meant to be the best on the market- surely it can operate two sources at the same time without that great a pressure loss?

doitall · 6 May 2006

They are the best, how they cannot supply more than the mains.

You need to check the mains pressure and volume first

fitz1 · 6 May 2006

if its been piped correctly u should have equal (balanced) pressure on ur hot and cold . therefore both should exit the tap with equal pressure.what does urs do.

davecon1 · 6 May 2006

if its been piped correctly u should have equal (balanced) pressure on ur hot and cold . therefore both should exit the tap with equal pressure.what does urs do.

Wow- speedy reply.

I've just checked all the taps and there is a bit more pressure from the hot water tap except in the kitchen where it is like a jetwash and the bath where it is noticably stronger.

Cheers

ChrisR · 6 May 2006

It's not uncommon for a Megaflo (-type) installation to provide less hot water than the system it replaced. Too many plumbers don't know what they're doing, unfortunately.
Anyone who installs one must by law have a "ticket" to do so. They can be dangerous if put in by a someone who's dumb enough to not understand the basics of pressure and flow.

davecon1 · 6 May 2006

The plumbers that installed it both had the Megaflo installer cards but they are not the most helpful of people. The pressure is 100% better than it originally was with the cold water storage in the loft but I'm just trying to figure out why the pressure is not the same in each bathroom!

Gasguru · 6 May 2006

The water pressure in the loft will always be less than the the incoming water pressure.

If for example you only have 1 Bar pressure (equivalent to 10 meters water head) coming in to your property the pressure at the loft shower head would be 10 meters minus the vertical height difference (typically 7 meters) minus frictional losses leaving perhaps only 3 meters or 0.3 Bar pressure.

If your incoming pipe is only 1/2 inch lead this will prove very restrictive and as you draw more water the pressure will further decrease as you have noticed.

The plumber should have measured the static water pressure (the real pressure in the street water main) and the dynamic or running water pressure when the taps are turned on. You can only then assess whether the incoming main is suitable.

Agile · 6 May 2006

Do you understand the diffference between pressure and flow???

bripl · 6 May 2006

enlighten us then oh great one

doitall · 6 May 2006

The plumber should have measured the static water pressure (the real pressure in the street water main) and the dynamic or running water pressure when the taps are turned on. You can only then assess whether the incoming main is suitable.

GasGuru has already explained Bripl.

Volume is the quantity of water avalable at the outlets, for example you could have 2bar delivering 10 litres/m with a 15mm pipe or 30 litres/m with a 22mm pipe.

Therefore you could have a good pressure but the flow rate drops off when you open the taps. which is probably whats happening to the OP

bripl · 6 May 2006

dia i do know how to measure static and dynamic pressure but mr a is such a patronising poster i thought i would attempt to add some humour with a hint of sarcasum

doitall · 6 May 2006

bripl said:
dia i do know how to measure static and dynamic pressure but mr a is such a patronising poster i thought i would attempt to add some humour with a hint of sarcasum

Yes I understand "thescruff" has told you enough times

Agile · 6 May 2006

In the traditional forum usage all replies are addressed to the original person as an answer to his question.

Of course in reality the original poster is often left wondering what on earth he has started!

Tony

bripl · 6 May 2006

two cheeky bar-stewards is enough

one patronising bar-steward is more than enough[mr g]

no offence mr g,you are normally pretty good with your diagnoisis but your posts appear to be arrogant and patronising to the point of blatant rudeness

davecon1 · 6 May 2006

Guys-

Many thanks for your responses (especially the banter between you some of you).

From what I've read it appears that it's normal to get less pressure upstairs than downstairs and that my megaflow is operating very much on the minimum requirements. The plumbers did measure the flow rate (though I'm not sure if they measured the static rate) and I will attempt to get around some of the problems by fitting flow regulators on the taps downstairs. I'll also try using a smaller showerhead as the Grohe had quite a big head.

Cheers.

diynot

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Poor pressure on a megaflo??

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