Megaflo or something else

[Extendingsoon]

I am extending my house to be 4/5 bed, 1 family bathroom plus 2 ensuites. I am also building a granny flat in the garden which will basically be a 1 bed flat. I need to accommodate me, my wife and two teenage kids in the main house and 1 person in the granny flat. I would really appreciate advice on what system I should use. Is Megaflo the answer for the main house and a separate combi for the flat - and if so what sizes should I go for. Or is there another type or make of system I should try.

Many thanks in advance.

 

[Doctor Drivel]

I am extending my house to be 4/5 bed, 1 family bathroom plus 2 ensuites. I am also building a granny flat in the garden which will basically be a 1 bed flat. I need to accommodate me, my wife and two teenage kids in the main house and 1 person in the granny flat. I would really appreciate advice on what system I should use. Is Megaflo the answer for the main house and a separate combi for the flat - and if so what sizes should I go for. Or is there another type or make of system I should try.

Many thanks in advance.

Avoid a megaflow. Use a heat bank. explanation: http://www.heatweb.com
Range do the FlowMax and many companies make them.

Megaflows can do this:
http://www.waterheaterblast.com

The Granny flat? It sounds detached. Is that so? I would be inclined to have the Granny flat with it own services and make it self-contained, not extensions from the main house. Have its own water supply, gas supply electricity supply.

If you don't, or can't, have separate meters. Then extend off the main house with maybe sub meters (owned by you).

You could have a small CH only boiler in the Granny flat and run in DHW from the thermal store using a secondary circulation loop that gives instant DHW at all the taps.

Need more details from you.

 

[Extendingsoon]

Thanks for your interest.

The Granny flat is detached, but for simplicity I would rather run all services from the main house - unless there are major benefits from having them separate?

Liked the Megaflo video - but that sounds a bit like someone selling me critical illness insurance i.e. if it's properly maintained/serviced it shouldn't happen.

However, I am very interested in any other options to the Megaflo. Can you please explain in laymens terms the difference/benefits of the other system you suggested.

On the Granny flat if I'm running DHW from the main house, can't I do the same with the CH? or is it a timing control issue?

 

[alexp.1]

Avoid a megaflow...Megaflows can do this:
http://www.waterheaterblast.com

Avoid ever getting into a car; they can do this:

PS. It's "Megaflo".

 

[Doctor Drivel]

Thanks for your interest.

The Granny flat is detached, but for simplicity I would rather run all services from the main house - unless there are major benefits from having them separate?

Divide and rule really. It could become a rented out place in future.

Liked the Megaflo video - but that sounds a bit like someone selling me critical illness insurance i.e. if it's properly maintained/serviced it shouldn't happen.

That is what they can do when the safety devices fail. They can take down the side of a house. Megaflows require an annual service which costs, just to store water.

However, I am very interested in any other options to the Megaflo. Can you please explain in laymens terms the difference/benefits of the other system you suggested.

A heat bank does the same as a megaflow but is failsafe and can operate on higher cold water mains pressures. No power shower pumps and other tripe.

A heat bank can also do the CH as well. The rads are run off the heat bank cylinder. So this means three CH circuits can be run off the heat bank. One for downstairs one for up and one for the flat. A Grundfoss Alpha auto speed pump on each and TRVs on all rads. No wall stats. In the flat a simple time clock to switch in and out the pump and boiler/heat bank. Same with the other two heating zones.

The boiler when heating a heat bank is operating in an ideal hydraulic environment. They heat up efficiently in one long efficient burn.

If I was you, I would go for a heat bank/thermal store. Have three CH zones off that. TRVs all around the rads with each CH zone having its own timeclock (upstairs can be switched off and downstairs on during the day) and have a DHW secondary circulation loop.

Take the heating to the flat in a large plastic buried pipe filed with vermiculite and the pipes with heaving insulation taped to them.

Make sure the cold mains is good enough and replace the stoptap with a full bore tap. Have an isolation tap on the gas and water to the flat inside the flat.

A heat bank may have backup electric immersion that do the DHW and CH.

Insulate the hell out of the flat and the extension, like 8 inches in the walls over 1 foot in the loft.

 

[leakydave]

Megaflo should be installed by G3 installer and they will not go 'bang'. If installed by idiots who don't know their a**e from an ef elbow they might!

Eggs in baskets... do you want the convenience of one boiler fulfilling all your hot water and heating needs vis two or even three zones, or do you want two separate boilers? One bigger boiler would be cheaper I reckon, but , if it were ever to fail you would be stuck... An immersion element in a megaflo would at least provide hot water backup...

Unvented cylinder every time for me if money allows and your water pressure/flow rate is sufficient...

 

[petit_pablo]

How many unvented cylinders have you seen go bang!

If installed properly there are no issues with unvented

 

[Corgigrouch]

Please read what I wrote. An immersion(s) can be backup for CH and DHW in a heat bank.








The immersion is going to heat the house??? how many elements and how many watts are they each ? surly to heat a house you would need a three phase supply.. So some kind of ear defender would be required for installing an unvented since they regularly go off bang and blow the house down.. Cant help thinking that you are scare mongering and I cannot see the reason for it. Yes an unvented is not a DIY proposition.. but like the plastic pipe debate it is a case of horses for courses..

 

[heatingman]

Thought I'd have a look at this thermal store site, I always think of Gledhill's and I've removed loads, never but one in (fitted unvented)
Yippy doo some one has stuck a plate heat ex on it. If I wanted a plate heat ex I'd buy a combi.
Had a look, had a think unvented for me every time.

 

[ChrisR]

How many kids have you seen scaled to death.

None at all.
It's the heat exchangers on thermal stores that get scaled to death.

 

[ChrisR]

Original poster - most important is that you check the incoming main pressure and flow - or get a plumber to do it for you.

 

[Extendingsoon]

I feel like I've lit the touch paper here! Bit of a contentious subject to say the least. But thank you to everyone for your input - most informative.

So as simple layman it seems I have 2 choices. The unvented Megaflo or the other one which I need to read up on as I don't know how it works.

So the next question is price comparison. Ball park figures, what are we talking as:

1. set up cost for the Megaflo in this case, plus annual service charges
2. set up cost Dr D's solution

Ignore labour charges if it makes the question easier to answer, given you don't know the layout.

While we are at it we might as well ask are there any other factors - apart from the house blowing up - that need to be taken into consideration e.g. typical parts that go wrong on either system.

Thanks again

 

[Extendingsoon]

Forgot to say, I intend to get the water mains from the road renewed to the larger pipe and will test the flow and pressure - but am told it will be ok.

 

[Softus]

How many kids have you seen scaled to death.

Well, Puff The Magic Dragon was responsible for a lot, but that was in the sixties.

 

[bpowell555]

This may seem a stupid question but why aren't megaflows fitted with failsafe stats like I just fitted to my immersion - if its fails - so I'm told - it fails in the off position, so my 3 year old in bed beneath the cold tank can sleep sound ...