Modern heating technology can make a major contribution to reducing energy consumption and protecting the environment.
In Germany alone, the modernisation of existing heating systems would reduce the energy demand of existing buildings by approx. one quarter and cut carbon dioxide emissions by roughly 30 million tons p.a.

Most modern systems for heating and hot water preparation continue to be based on oil- or gas-fired heating boilers. In these systems, especially the low temperature technology and the condensing technology make very effective use of the energy contained in fossil fuels.
Compared to older boilers, the latest condensing boilers achieve an extremely high energy efficiency. Boiler systems based on low temperature and condensing technology have emerged as the standard solution both in the construction of new buildings and in the modernisation of existing buildings in Western Europe.

Low temperature technology

In contrast to old standard boilers, low temperature boilers are capable of modulating their output. As a result, they operate at a much lower average boiler water temperature (flow temperature) than the previous models.
While the former constant temperature boilers used to heat up the heating water in the boiler to temperatures of 80 to 90 °C throughout the year, the flow temperature in low temperature boilers is dependent on the outside temperature and, hence, the actual heating requirements.

Given that the loss of heat in the flue gas as well as the heat losses from the boiler surface and the transport through the pipe system are much lower, low temperature boilers achieve a standard efficiency of 92 to 96 percent. They can be operated with either natural gas or heating oil.
While oil-fired low temperature boilers are today available in all output classes, the condensing technology has become the standard in gas-fired boilers.

Condensing technology

Condensing boilers achieve a standard efficiency of up to 110 percent and are the non-plus-ultra of heating technology in terms of energy efficiency.
Just like low temperature boilers, condensing boilers are dependent on the outside temperature but additionally use the condensation heat contained in the flue gas.
While the flue gases of low temperature
boilers escape through the chimney unused at temperatures of 150 to 200 °C, condensing boilers cool the flue gases to a temperature at which the water vapour in the flue gas condenses. The heat released in this process is used for heating.

A precondition for the use of condensing boilers is that the fuel used contains hydrogen. If natural gas is used, which consists of approx. 80 percent of methane depending on the type and origin, the theoretical additional heat gain is approx. 11 percentage points; if heating oil is used, the theoretical additional heat gain is about 6 percentage points due to the lower hydrogen content. Gas condensing boilers achieve a standard efficiency of up to 110 percent, while oil condensing boilers achieve up to 102 percent.

Due to the higher theoretical heat gain, condensing technology is used primarily in natural gas fuelled heating systems.