Combination of a Wood-Pellet Boiler-Stove with other Conventional and Renewable Heating System for Space Heating and Domestic Hot Water within A Passive House in Belgium

The present study, carried out within the framework of the PCC80 project (PCC80 stands for the Development of a New Generation of Condensing Boiler-Stove with recovery rate over 80 %), aims at investigating the possibility of combining a wood pellet boiler-stove (also called hydro pellet stove) together with other renewable (solar collector) and fossil-fuel (gas-fired boiler) heating devices within a detached single-family house in Belgium. A dynamic thermal simulation approach is used to assess the behaviour and the performance of residential heating systems as well as the occupant thermal comfort in a transient condition. The use of pellet boiler-stove within two different combinations, i.e. one is with only the solar thermal collectors and another one is with both solar collectors and a gas-fired boiler, is compared with the baseline system in which a gas boiler and a series of the solar thermal panels are used for space heating and domestic hot water (DHW) preparation. When using the hydro pellet stove, a fraction of the biomass combustion power is always directly released to its surrounding (i.e. the living-room) by the convection and the radiation, and potentially overheats the room if no space heating is needed. Different control strategies are therefore applied to the pellet-burning device and to the global system for reducing or avoiding this thermal discomfort. Generally, all three studied systems have succeeded in providing the required energy for space heating during the cold season and for making the DHW through the whole-year with the assistance of the solar thermal panels. The combination of gas, pellets and solar elements seem to be the best solution among studied system configurations.