How to Choose Boiler kW
Condensing boilers have the highest efficiency. They are distinguished by the ability of condensation of steam, in the case of non-condensing boilers, steam is released, while consuming a lot of heating energy. This means that the temperature of the flue gas is from 115oC to 120oC. A condensing boilerwith a more innovative heat exchanger can cool the flue gas to a temperature of 30 ° C to 40 ° C. Due to the better use of energy from spent gas, its consumption decreases. In this way, you will pay less for gas – bills can be reduced by 15-20% using a condensing boiler, and compared to an open flue boiler can reduce bills by up to 20-30%
Boiler too small (kW)
Each boiler, including a condensation boiler, cannot operate on low power as heat will escape through walls, roof, and windows. As a result, during cold weather, it would not be able to heat the building enough. However, you can still find yourself in such situation as older houses are not energy efficient.
The problem of unheated buildings can sometimes occur in big houses if the heating device does not have enough power, or during fixing of new central heating installation some problems occurred and wrong pipe dimensions have been used. However, good windows, insulation of walls, floor, and roof play a bigger role.
It is best if the boiler power is determined by a heating engineer (gas engineer). A range of factors are undertaken, including the way of heating up water. Warning! If you have concerns about the reliability of the insulation, you can choose a condensing boiler with 10-20% surplus (which will not affect its efficiency).
Boiler too big (kW)
Frequently, boilers are bought which have more power than necessary, especially in the case of combination boiler. While, for it to be able to supply at least 10L of hot water per minute, its power should not be below 20kW. If you require more hot water, then you can use a boiler of the power of 30kW or even 35kW. However, if you use a boiler with the power of 30kW-35kW while you house need 25kW, then after a short period of work it can give off enough heat to quickly heat up water and turn off. Thus, large temperature fluctuations can arise in the installation, and the building will be once too hot and once too cold.
If you want a small heating device which has more power, allowing more hot water, you should consider boilers with wide variations of power modulation. These can regulate the power from 20-109%, adjusting easily according to requirements. Such boiler can operate on low power, for example 5-7kW, in case of the need, you can easily increase the power in order to have enough hot water. Such operation of the boiler does not reduce its efficiency, so you should not worry. Though a condensing boiler can reach the highest efficiency.
Vaillant has a wide range of products which can easily satisfy your needs and provide the best solution for your house. Reliable work of those boilers is worth the recommendation.