Megaflo system - inadequate flow rate

[Doctor Drivel]

Because I'm planning to have a loft conversion, I thought it would be a good time to consider having a dry loft and installing a Megaflo system - the Heatrae Sadia Megaflo to be installed in place of the the hot water cylinder in the airing cupboard on the 1st floor. I currently have 1 bath/shower room and 1 shower room with another shower to be installed in the loft when it gets done.
The plumber came out and tested the flow rate and said that at 12 ltr/p min the flow rate was not enough for a Megaflo

Fit an accumulator, they work. Reliance do a good one. It is the size of an unvented cylinder. Then fit a high flow combi like the Ethos 54C @ 22 litres/min. The Ethos is a quality product and delivers. You don't want two large water cylinders in the house.

http://www.heatweb.com/products/accumulators/accumulators.html

http://www.heatweb.com/pdf/RWC/Accumulators.pdf
http://www.rwc.co.uk/Product.aspx?page=CAT6
No 3. Replaceable Membrane Potable

http://www.ethosboilers.co.uk/products_54c.php

Do not bother with a pump.

The best way is an accumulator. It is passive and requires no pumps valves or anything. Just one 22mm pipe to the cold water mains pipe and a double check valve at the stop cock. "" from accumulator to combi inlet. The accumulators does not and cold lines.

No needed for thermostatic shower mixers, just a combi mixer with an integral equalisation valve.

 

[lxbn]

Incidentally I'm currently having the kitchen re-done and let's not get started on that one - still on-going! davecon1 I can only sympathise in advance. I did though take the opportunity of having the mains feed upgraded to 22mm during the kitchen works - so I'll have 22mm from entry into the house to where I plan to site the megaflo unit on the first floor - if I ever do go ahead. That just leaves the outside - the last chap who came round thought it would not be that difficult as only flowerbeds would be dug up but didn't commit to a price nor a guarantee that this would do the trick - he did however give me a sensible price for installing the megaflo and converting the gravity CH to a sealed system. Have to check with Thames about lead times for connections in the West London area though.
Accumulators are an added cost and take up valuable space I don't have so I'm not considering that option yet. ChrisR, when you mentioned the salamander pump, did you mean this goes on the outlet from the cold water storage tank to the megaflo or does it go on the mains? The person at Heatrea Sadia may be wrong, but she informed me that the mains cannot be pumped. If the former, then will there not be a risk that the tank will run dry in times of high demand and cause an air lock? I hope I'm not asking foolish questions here.

 

[Nixt]

Avoid a Megalow and get a vented heat bank They are failsafe and do not blow up.

Does that mean an Alpha CD50 c/w unvented mains store is not failsafe and can blow-up?

 

[ChrisR]

lxbn
No you can't pump the mains. If your mains pressure is only 1.5 bar, I wouldn't rely on any mains powered system to get water rapidly to the loft. I know of houses where the pressure drops to about 0.9 bar at peak demand This means about 0.4bar static, in the loft. So hardly any water comes out of the taps up there even with no boiler in the way. You could manage it, by using large pipes and valves and careful choice of components, but you still wouldn't have much of a shower.

Which means you either have to pump water from a vented HW system, or from a CW cistern into an unvented HW system.
To save the HW storage space, you could use a pumped supply from a cistern going through a combi. As you say though, you need enough CW storage for whatever draws you have.

 

[simond]

if you have 1.5b at peak times the accumulator will do the job. If you can't afford it, that is a shame. Particularly when you consider how palatable the other options are.

 

[Agile]

Hi Chris

is there any pump on the market that will work with a megaflo. I've heard they do exist but in theory should not be fitted as it's straight off the mains.

You can use a break tank and a pump on the incomming mains supply.

But the cost of that is also high and uses up space. More relevant when you need lots of mains cold flow for short bursts and int incomming mains flow is limited.

Tony

 

[Balenza]

Ixbn wrote

and installing a Megaflo system

Avoid the megaflow. They can do this if improperly installed ....
http://www.youtube.com/watch?v=GF_Wrm-Ns0I

or this..........
http://www.youtube.com/watch?v=akqvaZ5J1aY&feature=related

 

[Biggles..]

Have a look at the Grundfos Home Booster. "00litres of stored with variable pressure and flow output.

 

[simond]

Crikey how shocking.

Or do I mean 'here we go again'. These American videos involve intentionally bypassing all the safety controls in order to get excessive heat into the cylinder.

We could blow up a Ford Mondeo by setting fire to its petrol tank. We could cause a dam to fail and video hundreds of people drowning. Or we could stop building tall buildings in case terrorists decide to crash planes into them.

Lets talk about the number of people injured or killed each year in the UK from unvented cylinder explosions.

Any figures anyone? Ideally I'd like the answers from those pushing tacky videos on this forum.

 

[Balenza]

simond wrote

Ideally I'd like the answers from those pushing tacky videos on this forum

Their is nothing tacky about those videos.
It demonstrates the power and capability of a steam explosion and I suspect you were unaware of this power until you saw the videos.
What is tacky on this forum however is those who push potentially dangerous UV cylinders when their are superior and safer alternatives available.

 

[simond]

You suspect wrong. It is common knowledge that when water turns to steam it involves an expansion of over 1000 fold.

In Victorian times it was not uncommon for steam engines to disappear along with their drivers and firemen. Usually the passengers were far enough away to survive.

However after about 20 years of explosions, the power was harnessed with various safety devices and since 1900 the incidence of steam trains blowing up was very rare.

I put it to you that you are doing the equivalent of the man walking in front of the car with the red flag. It dodn't pay well and he was soon made redundant.

Now where are those figures regarding unvented cylinder explosions in the UK?

 

[Balenza]

simond wrote

You suspect wrong. It is common knowledge that when water turns to steam it involves an expansion of over 1000 fold

If you know this then you wouldn't push potentially dangerous UV cylinders unto your customers.
You need to keep watching the video's over and over again until you get the message. (Though I doubt you ever will)

 

[simond]

Are you sure you aren't 'doctor drivel' under a different name?

Your advice to 'watch things over and over until I get the message' sounds strangely similar to his phraseology.

You want me to watch a tacky video where all the safety devices have been bypassed in a tin bucket and the contents are heated to the point at which steam is produced.

We should all marvel at what happens when water turns to steam. This was exciting to your ancestors four generations ago. We know how to handle it now.

Let's see the figures for the UK supporting your 'unvented bomb' theory.

I am, as ever, waiting.


PS: If you have any good Danni Minogue videos, I'm listening.

 

[Balenza]

simond wrote

I am, as ever, waiting

You won't have to wait much longer.

KABOOM...........................................

Especially with the amount of installers out there banging these systems in.
Add to that the cowboys and not forgetting the foreign imports who haven't a clue , then you have the potential for disaster.
I wouldn't have one in my home if I was getting it for free.

 

[simond]

I have one in my own home

And I am getting it for free.