Boiler information

The outside temperature control

• A temperature measurement of the departure water of the boiler
  
• A temperature measurement of the outside temperature
  
• A control unit with possibilities to set the heating curve

As shown in figure 2 the heating curve gives the set relation between the outside temperature and the desired water temperature. At e.g. 15°C outside temperature the required water temperature will be 20°C and at -10°C it will be 70°C. The heating curve will be chosen (set) according to the specific situation (installation, boiler, climate,...).

Once a heating curve has been set, the control system will provide just enough heat to see that the required boiler temperature is reached for each outside temperature. The water temperature of the boiler will therefor change constantly depending on the variation of the outside temperature. Therefore, it is also called
« gliding water temperature ».

The boilers on gliding water temperature for instance have lower losses than the boilers with a constant water temperature. For the constant water temperature control, the average annual water temperature may amount to 70°C. For a gliding temperature control it can be reduced to for instance 35°C. Maintaining boilers at a higher temperature is therefore not advisable from an energetic point of view. Savings of 10% and more can be realised. As already mentioned it might however by necessary from a technical point of view. For low water temperatures may lead to (temporary) condensation, and not all materials are equally corrosion resistant (e.g. steel plate).

Figure 2