Plumbing Design Mega Flo?

[smoo12]

Hi we are just about to start a conversion of a victorian terraced house. We converted a flat loft last year and were constantly annoyed that the combi boiler struggled wwhen two taps were on at the same time. Having read the forum for advcie I was wondering if anyone had any ideas on the following?

1- THe house will be three stories, with toilet and kicthen downstairs, a batheroom on the middle floor and an ensuite in the roof. (other rooms ion each floor will need Radiators)

Is it definitley a mega flo system that we require.

2- There is a natural cupboard on the middle floor , can the boiler and the mega flo go next too each other in there, or does the boiler have to go in the kitchen?

3- we have been told we have good pressure in London. Does anyone know what sort of calcualtions we should be asking the experts . The in tact pipe is 22ml.

4- we really want a responsive system but are out most of the day., We really would love to come in and have hot rooms quickly.

5- as we are already extending into the loft , is it better that we have an unvented system so that there is no need for an extra tank in the loft.

Any advice and if anythinhg is wrong above then please forgive me, as we are real beginners.

many thanks

 

[CBF]

pressure & flow is what needs testing (two totally different things), yes you can put both in the same cupboard if there is room (& the flue can be inspected throughout it's lenght), wouldn't fit a megaflow too expensive, there are plenty of others out there that will do the same thing but cheaper with the same warentee, don't forget the installer MUST hold the G3 cert for unvented

 

[dcawkwell]

Glow worm ultrapower a cross between combi and unvented cylinder.
All in the one nice neat box.
Will outperform a 300 litre unvented cylinder yet still work as a combi
should there only be two in the house.
Will supply up to 36 litres a minute of hot water (provided your incoming mains can handle this).
Also has immersion heater backup should the boiler fail for hot water.

30kw boiler will easily heat the house in no time provided your radiators
are sized correctly.

Beware some areas of london have hopeless flow and pressure so incoming
mains could be poor.

 

[MeldrewsMate]

Here's an alternative...
Can you keep the cold water storage (CWS) tank somewhere in the loft? If so then you could keep your vented hot water cylinder and install a 24kW combi above it in the airing cupboard. The combi DHW would supply only the en-suite on the top floor, leaving the stored hot water (generated conventionally from The CH output of the combi) to serve the middle and ground floors. In this way the combi would have sufficient power to supply the one outlet, and 24kW is ample to provide quick warm-up of the rads.

Using this method I recently heated a large 5 bedroomed house and two (mains pressure) hot water storage tanks, the combi instantaneous HW output feeding only the kitchen sink and the family bathroom's basin.

One downside of an airing cupboard boiler installation with hot water storage is the need to have access to every joint in the (vertical?) flue ("flues in voids"), others are the loss of airing space, need to guard against clothing/sheets etc touching the boiler case, and the raised temperature that the (expensive) electronics will run at.

MM

 

[flameport]

1- THe house will be three stories, with toilet and kicthen downstairs, a batheroom on the middle floor and an ensuite in the roof. (other rooms ion each floor will need Radiators) Is it definitley a mega flo system that we require.

Not necessarily - depends on water pressure and flow. One thing is certain - you do not want a combi.

2- There is a natural cupboard on the middle floor , can the boiler and the mega flo go next too each other in there, or does the boiler have to go in the kitchen?

Boiler and other items can go in many places. Just because many persons shove them in a kitchen doesn't mean you should.

3- we have been told we have good pressure in London. Does anyone know what sort of calcualtions we should be asking the experts . The in tact pipe is 22ml.

Location means very little. A test of the pressure and flow will confirm if it is suitable, and that's pressure with the taps open, otherwise you may find you have no water upstairs when the kitchen tap is used. Should also be checked at different times of the day as well.

4- we really want a responsive system but are out most of the day., We really would love to come in and have hot rooms quickly.

Any properly designed heating system will do that.

5- as we are already extending into the loft , is it better that we have an unvented system so that there is no need for an extra tank in the loft.

Probably, as the alternatives are a pump or a combination boiler.

Combination boilers are designed for use with one hot outlet at a time. They are often installed because the person suggesting it will make more money, as shoving one in will always be far quicker and easier than another type of system.
They are typically found in houses which are rented out - can't imagine why, as they are the worst type of system for such a situation. When it breaks, the tenants have no hot water or heating at all.

Those combination boilers which have internal storage are a partial solution to the fact that combination boilers are both feeble at providing hot water for washing purposes and at the same time are grossly oversized for space heating.

No doubt the next suggestion will be a thermal store - steer well clear of those as well.

Finally, consider that any system which is unnecessarily complex will go wrong and break in all kinds of ways you never thought possible, and therefore cost far more in the long term.

 

[Agile]

The Santon is the second name of Megaflow and much cheaper.

You need adequate pressure because 1 bar will be lost to the top floor.

Its essential that the pressure and flow are measured. Any real professional will know how to measure the dynamic flow rate!

But be aware many dont and only measure the open pipe flow rate which is not what is required.

Tony

 

[smoo12]

Many thanks guys,

If we do get the Dynamic test done, and its all ok,

Does anyone else have an opinion about using the glow worm ultrapower sxi 170 - It seems like a good comprimise, and allows us to do everythuing we need. - Sounds a bit too good to be true?

 

[sherbert]

if its made by Glowworm then it is to good to be true ............. Aviod IMHO

Go with a system boiler (Worcester, Valliant) and 250litre unvented if the pressure and flow are good ......

Job done and youve entered the 21st century

 

[mickyg]

nothing wrong with the ultrapower its a good piece of kit and reliable.......BUT........its far too expensive. Its cheaper to buy seperate boiler and cylinder, which is preferred.

 

[smoo12]

OK. So many differing replies its as confusing as just on the internet. We are starting form scratch, I am meeting the builder tomorrow and I would love to be armed with the knoweledge.

Assuming we have all the right flow rates - Whats the best way To make sure we can have ....

1- All the Taps and showers and Washing machines on at the same time ( if need be) - With unlimited heat and no loss - And be able to heat the radiators

2- Not have huge storage Tanks in the loft .

I am not saying money is no object , but space is, as its a small terraced house and I am willing to spend money on getting this bit right as in my flat , the combi boiler never quite got it to the right temperature in winter and the flow died when Two people used the shower.

Many thanks - And you are dealing with a novice sorry.

 

[mickyg]

well the first mistake your about to make is talking to a builder about heating and plumbing. Find a good installer independantly from the builder. Most builders own plumbers are often not very good, hence why they work for builders.

 

[SimonH2]

Combination boilers are designed for use with one hot outlet at a time. They are often installed because the person suggesting it will make more money, as shoving one in will always be far quicker and easier than another type of system.

Not just the installer, but the developer if it's a new-build or conversion - means they can shave a few square feet off each rabbit hutch.

They are typically found in houses which are rented out - can't imagine why, as they are the worst type of system for such a situation. When it breaks, the tenants have no hot water or heating at all.

Agreed, I can vouch for the fact that tenants aren't very understanding when matters beyond your control take over. For some reason, because it's rented, they expect things they wouldn't consider reasonable if they actually owned the place (and were responsible for maintenance).

No doubt the next suggestion will be a thermal store - steer well clear of those as well.

All I'll say is I've been happy with mine, and so have the tenants. Probably also the simplest way of having mains pressure HW, with electric backup for both DHW and heating ...

Finally, consider that any system which is unnecessarily complex will go wrong and break in all kinds of ways you never thought possible, and therefore cost far more in the long term.

Indeed.

One of the factors behind me putting the thermal store in the flat was to get the boiler down to "a box that makes hot water". So there is little in the system that I have to deal with outside numpties to maintain. When it takes "experts" a week to (not) diagnose a simple fault (failed microswitch, I ended up diagnosing it myself and telling them what to replace !), I prefer to have as little as possible that I'm not legally allowed to deal with.
And now the boiler only does one thing (heat water), it's been a lot more reliable - as in not had a single problem once in 2 years, whereas before it was needing attention most years.

 

[smoo12]

I have had my Dynamic water test done on my mains. - Do these number mean I could go for a system boiler?


Method
The static pressure was tested. The flow rate was measured at each 0.5bar. The flow was measured by timing the filling of a 10L container.

Results

Static Pressure - 3Bar
PRESSURE IN BAR FLOW RATE

Pressure in Bar / Flow Rate
3 0 bar - 0 ml/sec
2.5 bar - 182 ml/sec
2 bar - 303 ml/sec
1.5 bar - 455 ml/sec
1 bar - 526 ml/sec
0.5 bar - 555 ml/sec

 

[Agile]

You seem to have dynamic flow rate of 30 litres per minute at 1 Bar.

Thats considered quite enough to fit an unvented.

But unlikely to be enough to drive all your many taps at the same time.

You will need to fit a new large size supply pipe from the street at considerble cost. Most would live with it !

Tony

 

[smoo12]

What if I fit a new large size supply from the street , I could have an unvented system boiler and probably get all the taps in the house going at the same time, with good pressure?