Entire House Heating
In this diagram the energy partitioning of the heat generation between direct heat and heat transfer to the water is shown.
In the following chart you see in the left part the heat of the water of the stove, of the solar panels and of the oven in the seasons 2003/04 and 2004/05. On the right side the usage of both apartments and water for domestic use (e.g. shower) is shown.
Ertrag vs. Verbrauch
The following temperature-chart shows a part of one week in February 2005:
This shows that this system of the entire house heating satisfies highest requirements of comfort.
Measuring of emissions
In the year 2003 an on location measuring was carried out by the Research and Testing Centre of the Austrian stove-fitters. The exhaust gas was taken from the connector and was supplied by a sample gas tube and a gas conditioner to the analyzer. The fill-up quantity of wood, 16kg wood-briquettes broken into parts of 1kg, was piled into the heating insert and then lighted up. After that the measuring was started. The emissions of carbon monoxide were 566 mg/MJ and the efficiency 79.5%. For comparison the limits of the agreement according to clause 15a B-VG “Protective provisions concerning small firing plants” and “the economy of energy” of Austria are specified with CO 1100 mg/MJ and efficiency 78%. It is obvious that the measured values are much better than the limits, which are required at measuring at a test plant.
Details of the tested entire house heating appliance
The kachelofen is a heating insert with a connected ceramic flue system of fireclay and an air/water heat exchanger. The used heating insert is a grate-less insert for the firing of wood. The kachelofen is equipped with combustion air control for automatic shut off. To get as much heat as possible into the water the appliance is adjusted, that the air/water heat exchanger start at a temperature of 70°C and stop at 48°C. If the stove achieves 70°C again, the heat exchanger starts again. Because of this the maximum surface temperature of the stove is only 36°C.
The nominal heating time is calculated by the calculation-program of the Austrian Tile Stove Organisation. It is 11 hours as a result of the calculated nominal power of 4.6kW. Additional to the kachelofen there are 10 solar panels with an usable area of 18.5 m² and an incline of 27°.
The rooms not heated directly by the tile stove are equipped with wall heating surfaces.
Systems of kachelofen entire house heating
The simplest possibility for a tiled stove as the main heating appliance is an open architecture of the building, where the kachelofen release its heat without any heat transfer medium.
Another interesting possibility is the “Hypokauste”, a closed system with air as heat transfer medium. In this case the heat from the ceramic storages is transferred to the air, dispersed by ducts in the walls and finally heat up the room with the aid of heating surfaces in the walls.
The most important systems works with water as heat transfer medium. This system has following advantages: water is very good energy storage medium and it is a solution for the requirement of warm water in the same time. There are a lot of different technical systems with the heat transfer medium water: boiler, covering heat exchanger or air/water heat exchanger.
Mr. Thomas Hofer, a stove-fitter from South Tyrol and member of VEUKO, presented his project of an ntire house heating in his own house already at the meeting in Mals, 2000. At the last several meetings it was reported about the progressions of heating appliances for the entire house in different countries. In the year 2002 it was decided to make the project of Mr. Thomas Hofer a VEUKO project to cooperate crossnational.
Why entire house heating?
In the range of heat insulation a lot of improvement was made in Europe during the last years. The heat requirement of new built houses declined obviously. This leads to this, that the typical power of a kachelofen is sufficient for the heating of the entire house.
Development of the heating load (180m² residential house)
A kachelofen entire house heating is especially suitable for the use in Low-Energy and Passive houses.