How to choose between MegaFlow or Combi
This article explores the difference between a Megaflow system and Combi boiler. If you’re choosing a new hot water system, then you may be confused with the vast choice. Do you go for Megaflow or a Combi boiler? What exactly is the difference?
This article explains the difference between Megaflow (or its misspelling Mega Flow) and Combi (short for Combination) boilers and what situations they are best for.
By the end of this article you’ll be better informed about whether Megaflow or Combi is the best option for you.
What is a Megaflow System?
A Megaflow is also known as a Megaflow system or a Megaflow unvented system. Sometimes it’s called a Megaflow Boiler. In fact, a Megaflow technically isn’t a boiler at all. It’s a water tank or cylinder made of stainless steel that heats water.
Water from the mains feeds into the cylinder and is kept at mains pressure. This is why it’s called ‘unvented’. The result is you get a high pressure supply of hot water.
The Megaflow heats the water within it. There’s two ways it can heat the water:
1. an immersion heater heats the water. This is also called ‘Direct’ Unvented Megaflo; and
2. the heat from your central heating system. This is called an ‘Indirect’ Unvented Megaflow.
A Megaflow system only heats water and doesn’t heat radiators.
With a Megaflow you have a constant store of hot water.
Megaflows can be connected to solar panels or the electric supply, which is perfect if there’s no gas supply to the property.
Megaflows are manufactured by British company Heatrae Sadia.
What is a Combi Boiler?
A Combi Boiler is also known as a combination boiler. Combi boilers deliver instant hot water on demand without the need for any hot water tank.
This means you save on space as there’s no need to have a separate hot water cylinder.
The big difference is that Combi boilers also heat your radiators.
Since there’s no hot water cylinder to keep hot, they are very energy efficient and therefore much cheaper to run.
Unlike Megaflows, a combi boiler doesn’t require a much water pressure to operate, which is handy in areas of low mains water pressure.
There’s a big choice of manufacturers who make Combi Boilers, including Worcester-Bosch, Ideal and Baxi. You can read our review of the choice of Combi boilers in our article ‘What’s the best Combi boiler on the market’ here.
Or you can contact us and we can help you choose the best one for your home’s requirements.
How to choose between Megaflow and Combi
Large homes that have 3 or more bathrooms or showers where they are likely to be used at the same time, then you’re best getting an unvented hot water storage vessel, such as a Mega Flow. That way there be plenty of hot water for multiple baths or showers.
If you’re home is smaller with just 1 bathroom, then a Combi boiler is the best solution.
That being said, if you have no gas supply to the property, then a Megaflow system is the option for you.
Megaflow pros and cons
Lots of stored hot water
High pressure and volume of hot water up to 25 litres a minute
Can run up to 3 baths at the same time
No need for booster pumps for showers and baths
No need for cold water storage tanks as all off the mains water
Can use solar panels to heat water to reduce fuel costs
Can be installed when there is no gas supply to property
Minimum flow rate up to 25 litres of water per minute needed from water main with a minimum of 1 bar operating pressure on a 22mm diameter cold water main pipe
Takes up storage space
Very heavy and bulky
More electrical and mechanical controls that could breakdown
Takes about 45 minutes to recover when all the stored hot water is used up
Less energy efficient to run than a combination boiler if connected to electric only
Large sized water supply
Requires servicing every year
Combi pros and cons
Takes up very little space
Doesn't need much water pressure to operate only 0.7 bar. Or 7 litres a minute
Instant hot water when you need it only 20 seconds heat up time
You can have as little or as much as you wish of hot water as you like
Very energy efficient as there's no need to heat any storage vessel
Half the cost of an unvented cylinder and boiler installation
Cheaper to maintain and service
Therefore, perfect for smaller properties (3 bedroom and under)
No risk of legionella
Can run on oil, gas, electric and LPG
Less electrical and mechanical controls to breakdown
Up to 98% energy efficient and A class rated for efficiency which means they cheaper to run
Can only run 1 bath or shower at a time
Will not cope with more than 2 bathrooms working at one time
May require bigger gas supply
Needs gas to property
Can only deliver a maximum of 16 litres a minute of hot water
Not suitable for large properties with more than 2 bathrooms
Mega Flow or Combi ? Which is Right For You?
So which is right for you – Mega Flow or Combi? As you will have seen, it largely depends on the number of bathrooms you have and whether you have gas supply. If your property is 3 bed or under, then consider the Combi boiler. If you have more than 3 bedrooms and more than 1 bathroom plus you have the storage space, then a Mega Flow will be a good option.
Disclaimer: The information contained on this website if for general information purposes only. You should not rely upon the material or information on the website as a basis for making any decisions or actions and we don’t accept liability for anything you chose to do with the information.
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