In its most fundamental form, this is simply a metal box that is surrounded by a fire. In fact, the first heating systems were just this, a metal box referred to as a back boiler, found within the fireplace of the lounge. Surprisingly, there are a few still out there in some older properties.
How Boilers Work and Their Fuel Sources
- A boiler is the appliance used to heat water for the purpose of supplying a central heating system and hot water to taps. The term ‘boiler’ is not ideal, however, because the water never actually boils inside the appliance – if it did, there would be something seriously wrong. Boilers today are fully automatic devices that turn up the heat as necessary and, with the exception of solid fuel systems, completely turn off when not required. The water is just heated until the required temperature is achieved, as set by its built-in thermostat, and then the heat source turns off. The fuels that could be used for the boiler include:. Solid fuel, including coal, wood and straw
. Electricity
. Gas
. Oil
Electric boilers are quite rare and so they fall beyond the scope of this book. The remaining fuel types, however, have been used in boilers for many years, and the design of the boiler has developed into a very efficient appliance, unlike those of yesteryear. Ideal Commercial Boilers Solid fuel has limitations in its design, and because these boilers tend to be more labor- intensive – i.e. you need to load the fuel and empty the ash – they are not very popular and account for around only 0.5 per cent of all installations. Around 92 per cent of installations use gas and the rest use oil.
Types of Boilers and Their Functionality
Due to developments over the years, there are many different boiler designs from many different manufacturers, with a neverending list of models applicable to the particular designs as well as varied price options for home heating and cooling. But fundamentally they all fall into one of four basic types:
- . Natural draught open-flued
. Forced draught open-flued (fan-assisted)
. Natural draught room-sealed
. Forced draught room-sealed (fan-assisted)Essentially, these names relate to the method by which air is supplied to the boiler: - Natural draught or forced draught indicates whether or not the appliance has a fan incorporated to assist in the removal of the combustion products to the outside.
- Open-flued boilers take their air from within the room where the boiler is located.
- Room-sealed means that the air is taken into the boiler from outside the building.
Identifying Your Home Boiler Type
- The boiler in your home will be of one of these. For example: If you have a back boiler situated behind a gas fire in the living room, you have a natural draught open-flued boiler.
- If you have a large free-standing boiler in your kitchen, with a flue pipe coming from the top, travelling into a chimney or passing through a pipe to discharge up above the roof, again this is likely to be a natural draught open-flued boiler.
Both of these types take their air from the room in which they are installed, and this air is replaced via an air vent from the outside. If your boiler has a terminal fitting flush with the wall, it is most likely to be a room-sealed appliance.
- If this terminal is quite large, it will be of the natural draught type.
- If it is smaller, say about 100 mm in diameter, it will be fan assisted.
These boilers do not take the air required for the combustion process from the room, but directly from outside.
