Energy-efficient building renovation in Waldkirch

Energy-efficient building renovation – Oskar stratified storage tank and Max AirMono F67 air source heat pump

The Max AirMono F67 air source heat pump

Our energy and heating concepts rely on the interaction of various heat pumps. A stratified storage tank acts as the heart of the entire system, to which up to 18 heat sources can be connected. A new addition here is the Max AirMono F67 air source heat pump, which has a total output of more than 80 kW. The Max-AirMono F67 heat pump is a speed-controlled air/water heat pump in a monoblock design for outdoor installation. It uses the natural and environmentally friendly refrigerant propane. The system consists of two independent refrigeration circuits, which are linked via an intelligent cascade control system and combined in a single housing. There is a common hydraulic and electrical connection. Hydraulically, the refrigeration circuits can be connected either in series or in parallel, allowing a water-side spread of up to 20 Kelvin.

The generously dimensioned, V-shaped evaporator, which is equipped with alternating and hydrophilic-coated fins, reduces defrost cycles to a minimum. The 100 cm diameter fans prevent disruptive air noise while maintaining a high air flow rate. The triple sound-decoupled compressor also contributes to the quiet operation of the heat pump. The refrigeration circuits are filled and ready for operation, so no refrigeration certificate is required for installation. The safety valve integrated in the outdoor unit and the microbubble separator ensure that, in the event of a leak, the flammable refrigerant does not enter the boiler room. The speed control of the heat pump covers a wide range of outputs and thus adapts to different loads and conditions. In addition, it is ideally suited for use with fluctuating energy quantities and enables intelligent load control across all energy ranges.

The ratiotherm WP Max-AirMono F67 air heat pump has two complete refrigeration circuits and uses outside air as its primary energy source. The design means that no moving parts are visible, which in turn has an impact on noise levels. The air heat pump is designed for all weather conditions. The outdoor unit is installed outdoors in such a way that air can flow unhindered through the evaporators and does not recirculate. Two axial fans convey the air to the evaporator. The refrigeration circuit is a hermetically sealed circuit consisting of a scroll compressor, a condenser (plate heat exchanger), an evaporator (fin heat exchanger) and electronic expansion valves that control the flow of refrigerant. The natural refrigerant R290 is used as the working medium. The WP Max-AirMono air source heat pump is delivered ready for operation with fully filled refrigeration circuits. The heat pump can be controlled by the ratiotherm rZR 16×2 central controller or by a third-party controller. If the unit is controlled by a third party, an external display can be installed in the boiler room to show all parameters and operating states at a glance. The ratiotherm air heat pump can be operated in combination with most electric, gas or oil boilers.

Renovation example – apartment buildings in Waldkirch

The first renovation project using the WP AirMono F67 involved an apartment building in Waldkirch near Freiburg im Breisgau with a total of 12 residential units. The residential complex to be renovated was built in 1958/59 and consists of two sections of the building that are directly adjacent to each other, slightly offset to the side, but otherwise completely independent and separately accessible. Each section therefore has its own stairwells, cellars and storage rooms, as well as its own self-sufficient connections for building services (water and sewage, gas, electricity, telephone). All flats are currently supplied with heating and hot water in a decentralised manner by means of their own gas water heaters. The flats therefore have gas and electricity meters (in the basement) and bill their energy consumption directly to the energy supply company. However, there are no water meters in the flats, so that only a flat-rate billing method can be used here.

Accordingly, there is no technical room for a central heating system or a storage room for fuel. In future, heat will be supplied by a central air-water heat pump shared by both houses, which is filled with propane as a refrigerant and can generate temperatures of up to 70°C. The heat pump will be installed entirely outdoors on concrete foundations and will supply the heat distribution centre via a short, underground supply line. The heating system will be supplemented by an on-site PV system, which is designed to produce the annual electricity required for the heat pump heating system. Two heated water stratified storage tanks, a fresh water station, a two-group heating distribution system and a 12/18 kW power-to-heat system are installed in the boiler room. The power-to-heat system uses surplus electricity to directly heat the stratified storage volume before it is fed into the grid, thus reducing the high-temperature operation of the heat pump. The successful interaction of several components, such as a PV system, Oskar stratified storage tanks (2x with 1,000 litre capacity, welded on site), PV Max-Heater (conversion of renewable electricity from, for example, photovoltaics (PV), wind energy or biogas into heat. This heat can be stored very easily and in an environmentally friendly manner in large heat storage tanks – unlike complicated battery storage systems. Thanks to the interaction of several components, such as the PV system, Oskar stratified storage tanks (2x with a capacity of 1,000 litres, welded on site), PV Max-Heater (conversion of renewable electricity from, for example, photovoltaics (PV), wind energy or biogas into heat), drinking water cascades, specially programmed control technology and the AirMono F67, all project goals were achieved.