Combi versus Megaflow

[drian]

Hi,

I live in a top (second) floor flat and the landlords are about to add an additional floor to the block and so our old storage tank heating system needs to be replaced which will be done free of charge.

We can chose either to have a combi boiler or a mega flow system and I do not know which one is best to choose.

The flat is 2 bedroom, 1 bathroom with 2 occupants, the water pressure is good.

We would like to chose the best system for us as its free(!) with the least disruption, re-piping work etc.

Any advice would be really appreciated.

 

[twgas]

Most people would consider an unvented cylinder ( 'megaflow is just a trade name) as superior to a combi.
Providing your incoming main is up to it the flow rate would be better. A combi would probably need less unheaval to install, would take less space and provide a neverending supply of hot water (unventeds need reheating from scratch if totally exhausted)

 

[scoobydo123]

I would be asking if the unvented they are installing are indirect or direct. If you pay the bills you may not want to have direct as these are heated via an immersion(s). The cost per kw for electric is much higher than gas.

If indirect then I would go for that especially as these can also be fitted with immersion if the new boiler breaks down so you still have hw.

 

[drian]

Sorry for ignorance, but please can you explain the difference between "direct" and "indirect"

Many thanks

 

[twgas]

Basically, direct is heated by immersion, indirect by a boiler.

 

[Agile]

You need to ensure they fit an indirect unvented cylinder and that it meets the rule of thumb of 50 litres plus 50 litres per person as a minimum.

Better 225 litres in case more people come to live there in the future.

Tony

 

[ianmcd]

I would go for a combi if you only have one bathroom will be cheaper to run UV are great but you wont really notice the difference with one bathroom and are more expensive to run

 

[JohnD]

fill a bucket at the (mains supplied) cold tap and time it. How many litres per minute do you get?

in most houses it will be the kitchen cold tap, but sometimes the bath tap is also at mains pressure.

you are measuring flow, which is not the same as pressure.

 

[Agile]

An unvented fills a bath quicker and can supply a higher flow rate shower!

It can also supply a shower AND a kitchen tap at the same time ( if the mains supply is adequate.

Of course both of those features are something of a luxury and tenants usually have to live with a minimum power combi!

Tony

 

[David937]

Out of interest, are you renting this flat? If you are, your lanlord seems very generous to let you choose which system you'd prefer!

 

[Whitespirit66]

Space may be another consideration in a flat. With a combi, you will just lose the space taken by the boiler. With UV (indirect/boiler), you still lose the space of the boiler, but in addition, you will lose a whole cupboard to the unvented cylinder, associated pipework, valves, timers, etc.

In a 2 bed, 1 bathroom flat occupied by 2 people, I would probably go for a combi. Other benefits are unlimited hw, and only paying to heat the water you use.

 

[drian]

Out of interest, are you renting this flat? If you are, your lanlord seems very generous to let you choose which system you'd prefer!

Hi, The leaseholder wants to add another story to the building utilizing the current loft space. The current water tanks will have to be removed and so we will have to move to a mains water supply..

Luckily the lease holder wants to keep a good relationship and so a choice of heating is one of the incentives he has given to the flat owners to help him to have a smooth project.

 

[gigz]

In your scenario i would go for a combi, as already said an unvented system is great for more bathrooms/showers etc, but make sure they are fitting a quality boiler, you get what you pay for with a combi and a lot of the cheaper ones will let you down. P.S. you can still have a good powerful shower with a combi, but don't open another tap while its being used