scope:

This part of EN 12309 deals particularly with the specific provisions of hybrid heating appliances based on gas-driven sorption heat pumps as defined in Part 1.

The heating appliances covered by this European Standard are of a hybrid type, an encased assembly or assemblies combining a direct or indirect-fired sorption heat pump for base load and a peak load condensing boiler with only one flue system, electrical supply cable and human machine interface to the end user. The direct- or indirect-fired sorption heat pump integrated in the hybrid appliances in this European Standard could be intermittent or continuously operating ab or adsorption heat pump.

The control system of hybrid heating appliances decides on the transition between the heat pump operation mode to/from the mixed operation mode (heating by both sorption heat pump as well as the peak boiler) and the direct heating mode (only peak boiler) depending on the heating fluid inlet or return temperature, temperature of brine entering the indoor heat exchanger (evaporator) of the heat pump, the required outlet or supply temperature dependent on the outdoor temperature as well as the target value of the indoor or room temperature. Upon transition from the heat pump operation mode to the mixed operation mode, the control system decides also on the degree of mixing based on the above mentioned parameters.