Central Heating System Fitters and Installation in Lothian, Scotland
There are three different types of domestic heating and hot water boiler, combination boilers (known as ‘combi's'), system boilers and open vented boilers. Since April 2005 your new boiler must, by law, be a high efficiency boiler or condensing boiler. This is a boiler that recovers heat that would otherwise be wasted and uses it to improve the boiler's heating efficiency.
How do they work?
High efficiency or condensing boilers (they are the same thing) have a heat exchanger that uses heat in the flue gasses to pre-heat the water. (They are called condensing boilers because most of the heat recovered comes from condensing water vapour in the flue gasses.) The condensed water is drained away and much less energy is required to raise the temperature of the preheated
circulating water to the desired level.
A combi boiler eliminates the need to store hot water so there is no hot water cylinder in the airing cupboard. It is both a high efficiency water heater and central heating boiler. The boiler runs ‘on demand' and provides hot water to the heating system in the house or flat.
System boilers are often referred to as sealed system boilers because the system is filled to approximately 1 bar pressure and sealed.They are connectedto a hot water storage cylinder, usually installed in an airing cupboard. This type of boiler does not need an expansion tank in the roof. They are particularly good for homes with more than one bathroom because the combination of boiler and hot water cylinder can deliver hot water quickly to several outlets simultaneously.
Open vent systems are normally connected to two tanks in the loft. A small ‘feed and expansion tank' supplies water to the boiler and the radiators. A larger domestic cold water storage tank provides the cold water feed to an open vent hot water cylinder. Although replacing the boiler and linking it to an existing open vent system is an option, most people opt to remove the tanks from the loft and to install a sealed system boiler or a combi.