ONE FOR HEATING, ONE FOR DHW
Main characteristic of the concept
One heat pump system for each mode. One for space heating, separate one for DHW.
Heat distribution and temperatures levels
Because of the separate production of space heating and DHW and, consequently, different supply temperature levels, each heat pump may be optimized for own purpose. It includes, for example, the capacity of the heat pump and the refrigerant.
Size of building, number of apartments
This solution is suitable for all sizes of buildings, but often used for larger buildings.
DHW and storage characteristic
Storage tanks for DHW are needed. Heat pump must meet high temperature requirements of the DHW. Central distribution of DHW results in high distribution energy losses. Separate consideration about legionella needed (for example ultra-filtration).
Energy standard, insulation level
This concept can be used for buildings with a high, as well as a low level of insulation. In new buildings two temperature levels are possible, which allows to optimise each heat pump for certain temperature level. Using two different heat pumps allows implementation of different refrigerants.
Complexity of installation
In case of retrofitting, the old heating distribution system can be maintained. In some cases, partial or complete exchange of radiators in each apartment may be required. In case of new buildings, long piping through the whole building is necessary.
Heat Sources
All heat sources possible. Using two different heat pumps allows also for using two different heat sources. For large buildings with high energy demand the heating capacity may be a limitation factor for outside air as a heat source. When outside air is used as HP-source, the HPs preferably should be installed on the roof. For larger systems the sound emissions may be a problem for air source heat pumps.
Specific issues of the concept
The old heat generators may be replaced (during retrofitting) without changing the distribution system. Specific heat pumps for each mode may be beneficial in terms of lower capacity needed, used refrigerants, chosen heat sources, etc.).
Positive aspects
- Good for larger MFB’s
- Splitting functions may lead to higher efficiencies
Negative aspects
- High distribution losses