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Installers of Gas, Solar and Oil Heating Systems
 
 
Are you looking for a combi boiler? If yes, then ask yourself why! Chances are you were 'sold' a combi boiler solution by a plumber giving you a quote to replace your old boiler. Unfortunately most people are unaware of the many disadvantages of a combi boiler. Combi boilers are suited to some situations such as small one person flats, but on the whole they are misold as a panacea to all heating systems. If you still think you want a combi boiler, then read on.

Limitations of a combi boiler

  1. If you have a combi boiler, you will know that the flow rate goes to a dribble when more than one tap is open.Caroline Brannigan wrote an excellent article in the Guardian highlighting the problems with a combi system. You may need to remind your guests not to flush the loo or wash the dishes when you take a shower!
  2. A combi does not have any form of hot water backup if there is a fault with the boiler. Most systems with a traditional or megaflow cylinder have an immersion heater in case the boiler breaks down.
  3. Limescale is a serious Achilles heel to combi boilers. If you get any limescale forming in your kettle then the same limescale would block or severely restrict the heat exchanger of a combi boiler.
  4. The radiators go cold when you draw a bath. A typical problem where a combi is installed in a large house. All the power from a combi boiler is diverted to heat the water, so the radiators will go cold.
  5. Maintenance costs can be higher for combi boilers. Typical diaphragm replacements are needed every year or so and a repair bill of £100 each time is not uncommon. There are some exceptions to this rule and we will be happy to explain certain boilers that do not suffer from such problems.
  6. Lack of airing cupboard. Some people enjoy the constant warmth from a cylinder to air their clothes. Even the most efficient cylinders will emit some warmth and you would not have this benefit with a combi setup.
  7. Gas usage can vary widely. If you think of a combi as a boy racer and a cylinder setup as a granddad, which will use the least amount of gas? With a combi, every time you turn on the hot tap, the gas meter will go around flat out, i.e. boy racer. With a cylinder and condensing boiler you are using your energy more efficiently because the boiler will be in condensing mode almost all the time while heating the cylinder, hence the granddad analogy!
  8. Gas supply pipe will be larger for a combi boiler. A 'boy racer' combi boiler will demand a lot of gas in a short space of time. Therefore it is obvious that a larger gas pipe will be required from the meter to the boiler. Prices for 28mm gas pipe 'installed' can be as much as £15 per meter so it quickly becomes very expensive!
  9. A combi boiler is usually woefully underpowered to supply heat and hot water for a home. Combi boilers supplying several bathrooms and 12 radiators is not unheard of. It soon becomes becomes a source of arguments and a sore point when several people are demanding hot showers, especially in winter when heat is most needed.

We understand that some people simply don't have the space for a conventional cylinder. You shouldn't overlook the fact that it is now possible to buy cylinders that are small enough to fit under a kitchen worktop.