Do megaflows etc really work OK on less than 20litres min ?

[mickyg]

OP-Your just below the limits of acceptability for an unvented system. A new upgraded mains supply might well be enough to make it doable. alternative solutions are pump sets and/or an accumulator. Alot of areas suffer with poor mains supply but there's often a reasonable solution. There are quite alot of areas of poor pressure in Hertfordshire, combined with the incredible hardness in some areas you could say we have possibly the worst supply of water in the UK

 

[mrsdecisionmaker]

If lots of money could buy pressure and flow from the mains then cost is not a problem. My point is that these systems seem so dependant on mains flow and pressure ( ie variables outside your own control) that they are the wrong solution for most people. ie mains pressure at kitchen stopcock 2 bar 18litres/min ( 10.30am). They don't function well in certain areas. Or is it like buying a fast car and then using it to drive in traffic - you've got the brand/image and the function doesn't really matter?

 

[mickyg]

I don't know what your getting at. You make sure the house has the correct flow and reasonable pressure. You install the system, it works, job done. People don't just buy them and hope they work unless they are very stupid.

 

[mrsdecisionmaker]

Agreed you need the correct flow and pressure - but if you are in a not great areas for water then the solution is not an unvented system. It is only by upgrading pipework/ getting an accumulator /Dualflow etc add ons to the pressurised unvented system that the thing works.

Whole areas should be off limits for megaflows and their kinds surely ? If they work without all this fiddling then great but it seems a bit ott if all you really want is a decent shower... thank you for the input.

 

[tamz]

It seems like you are waiting for someone to talk you out of your "decision" to "think" about having an unvented cylinder installed. If you cant get the pressure and flow required then forget it. They are not suitable for every installation.

If all you want is a "decent" shower stick a 3 bar pump on it. Flow rate up to 24 litres/min for around £6 - 700 fitted. Big rain showers, multi heads, body jets you can even pump the whole house. Whatever lights your candle.

 

[mrsdecisionmaker]

Yes I think you are right ! But 'megaflow' systems have street cred /big marketing budget and I am trying to work out why they are so appealing but actually aren't always the right choice.

 

[mickyg]

Yes I think you are right ! But 'megaflow' systems have street cred /big marketing budget and I am trying to work out why they are so appealing but actually aren't always the right choice.

because they will provide almost as much flow as you put in, they last for 30yrs or more with limited maintenance, they don't make any noise, they usually come with HE coils suited for Weather comped systems.... Not the answer to every problem but a good option for many.

 

[tamz]

A 12 inch shower head and some body jets will get the street cred with the naybores. They don't need to see in your airing cupboard

Unvented or mains fed (combi's) have had to be fitted to new builds for the past few years so people are more aware of them so there is a massive market for them as most homes still have storage tanks.
As mickyg says they have a lot of advantages over the old systems but they are not suitable for all.
Even if you only had 0.5 bar and 10 litres a minute it would still "work", you would still get hot water at your taps. But what would be the point of spending all that money for something that looks good in its shiny white casing but in reality is no better than what you already had.

Speak to a good plumber, not some course cowboy or A1A1A kwikplumb? from yellow pages. If you want a really great shower there are a few ways to do it without unvented.

 

[mrsdecisionmaker]

Water company are coming again to fix our street stopcock which is broken and then measure pressure/flow there to see if any benefit from replacing our bit of the outside supply pipe that runs in garden. Only able to measure internally on first visit. We are linked via a communication pipe to the mains which is on the other side of the street, so they will also measure mains, not expecting more than 0.2 bar difference.

If we choose to replace our pipe with 32mm it is regarded as a new supply and a water meter will go on. Replacing existing with 25mm doesn't trigger a water meter.

Water company very helpful and quick to respond so checking pressure/flow is easy.

 

[tamz]

Renewing the stopcock and supply pipe might (will) give a slight increase in flow but the pressure will be the same.

 

[griggs]

Yes I think you are right ! But 'megaflow' systems have street cred /big marketing budget and I am trying to work out why they are so appealing but actually aren't always the right choice.

Very often when these are installed, the difference between them and the previous vented system that they have replaced is significant enough for the end user to be impressed and happy with them, the people who will not necessarily be as happy are those that have done lots of research on them and who are going to measure the flow rates at their outlets to ensure they've got every last litre they have paid for. In your case, it seems that you have a neighbour who you could chat with and ask them how they get on with it, but I bet they won't be able to tell you jow many L/min they het from their shower whilst the kitchen sink is being used at the same time.

 

[mrsdecisionmaker]

Stopcock replaced and flow measured at 18/20 litres minute and 2.5 bar pressure. Water technician's opinion was we need to put in a 32mm pipe to make a 'megaflow or other' type system to work, and even a vented system would work better with a better flow rate than the 13litres/min got now. With 32mm we should then get flow of minimum 20litre/min internally. Currently have a thin copper pipe across garden to house. Just getting a quote for 32mm in our garden.

 

[mrsdecisionmaker]

Going for new supply pipe tomorrow a.m. as while there is a hole in the pavement there is an easy one off opportunity to link in direct to the external stopcock. ( There is a big tree on our boundary whcih would make it very difficult once the hole in the pavement is closed up). Then we shall see if pressure and flow are improved as per prediction. Hopefully it is 20l and 2 bar and then we will go for unvented. If not we just have a new blue pipe !

But unvented needing flow and pressure in order to work is a bit mad when the water systems weren't really designed for this and the minimum legal service provision of the water companies would leave unvented users up the creek literally if unforseen events in the future meant the water systems couldn't do on average what they do now. At least with a cold tank and pumps on your premises it is all in your control.

 

[tamz]

Decisions decisions

You'll be fine with 18-20l/m at 2 bar and won't notice the difference with a little variation in flow rate or pressure. Pressure varies slightly throughout the day as demand rises and falls. Generally a bit higher at night.

 

[mrsdecisionmaker]

32mm now connected. Definitely more water coming out but rough bucket testing tonight maybe 16litres/min so not a flood given size of incoming. Plumber coming to test for real. Voucher for boiler hopefully arriving soon