Megaflow Cylinder Central Heating SystemA short guide to choosing the right hot water cylinder or boiler

Choosing a central heating system is an important investment. It can save you energy and fuel – therefore money. In addition, choosing the right central heating system can add value to your house. But it is not just a case of choosing a brand of boiler there are other things to consider.

There are three main types of heating systems to choose from:

  • Combi Boiler Systems
  • Gravity Fed Open Vent Systems
  • Megaflow or Pressurised Systems


What are the advantages and dis-advantages of each of these hot water systems?


Combi Boiler Systems (or combination boiler systems)

This type of boiler system heats the hot water on demand. This means that you no longer need a cold water storage tank in the loft or a hot water cylinder in the airing cupboard. So this is often the type of boiler system chosen when space is limited such as in flats or when a loft has been converted. It is one of the cheapest options however it is connected to the mains water so when more than one utility is used, for example if you are having a shower and someone downstairs is washing up, then you will notice a drop in pressure to the shower head.  So these types of systems are not recommended for homes used by families with children or houses with multiple bathrooms.

Gravity Fed Open Vent Systems

This is the most common used hot water system installed in homes in the UK.  However, since the introduction of combi boilers and megaflow pressurised cylinders, many houses have been upgraded to these more efficient central heating systems. If your home already has a gravity fed open vent system, it is often far more cost effective simply to upgrade your existing water cylinder and boiler rather than install a new expensive system. However the disadvantages of these systems are that they rely on gravity so pressure is often lost in flats where a large water tank cannot be installed in a loft. Furthermore, there is a higher risk of damage from frost during the winter months as the complete system is usually installed in a loft.

Megaflow High Pressure System

These are often used following a loft conversion because they can be installed in a garage or other area of the home. They do not rely on gravity but take water directly from mains water and operate at higher pressure negating the need for shower pumps etc. This system is ideal for larger houses with families – especially if you have more than one bathroom or shower room. The disadvantage of this system is that it is more expensive than both the gravity fed hot water system and the combination boiler. Plus it is not possible to guarantee old pipework due to higher water pressures.

We installed a Megaflow High Pressure System in Tewin.

If you would like to discuss which central heating system is right for your home, contact us for a free no obligation quote, call 07977 924459 or email