There are three different types of domestic heating and hot water boiler.
- Combination boilers - This type of boiler eliminates the need to store hot water. It is both a high efficiency water heater and central heating boiler, it provides hot water ‘on demand’ and provides hot water to the heating system.
- System boilers - These are sometimes referred to as sealed system boilers, the system is filled to approx 1bar pressure and sealed. There is a hot water storage cylinder. This solution is particularly good for homes with more than one bathroom as the combination of the boiler and hot water cylinder hot water can be delivered to several outlets simultaneously.
- Open Vented boilers - These are normally connected to two tanks in the loft. A small ‘feed and expansion tank’ supplies water to the boiler and radiators. A larger domestic cold water storage tank provides the cold water feed to an open vent hot water cylinder. Most people opt to remove the tanks from the loft and install a sealed system boiler or a combi.
Since 2005 your new boiler must by law be a high efficiency condensing boiler.
High Efficiency also known as condensing boilers 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.
Vaillant SEDBUK ‘A’ rated boilers in the ecotec range operate with an annual average efficiency of over 90%. Typically older boilers only achieved in the region on 56%.