How to choose a Nordic Tec plate heat exchanger to connect the heat pump to the heating system
Heat pumps as a heating device are quite a demanding solution from the point of view of heat exchange, which translates into the objective need to select a heat exchanger with a larger area than, for example, for classic boilers of similar power. The reason is both the fact that they usually operate at much lower deltas, as well as the desire to ensure that the heat pump works with the lowest possible power consumption, as a rule.
Below we present a series of types of heat exchangers that are most often sold for heat pumps. Of course, it is about connecting the HP to the installation, in the water-water or water-glycol system, these are not freon exchangers or the units for the so-called R factors.
In the case of heat pumps, the selection depends not only on the nominal power of the HP, but also on the temperatures at which the central heating system is to operate. This is not about the maximum performance of the pump, but rather about the operating temperature that we expect from the pump so that it is able to provide thermal comfort at home. The lower it is - the larger the heat exchanger will be needed, but it is worth keeping it as low as possible, due to the expected operating costs.
The plate heat exchanger for the heat pump should be sized depending on the expected operating temperature of the pump:
The first case is a classic arrangement in which radiators play the main role, and floor heating is possibly an addition. In such a facility, the operating temperature of the pump must be min. approx. 50 °C for the radiators to work optimally. For such systems, approx. 1.50 m² of the heating exchange area should cover each 10 kW of the heat pump (working on 50°C).
The second case is facilities heated in 100% with underfloor heating, where the operating temperature of the pump will be required at the level of about 30 - 35 °C only. In such cases, the heat pump works very economically, but a relatively large heat exchanger system is needed for efficient operation - the sizing converter here is approx. 3.0 m² of heat transfer area for every 10 kW of heat pump (operation at 35°C).
Intermediate options, i.e. supply temperatures of 40 or 45 °C, should be sized proportionally.
The presented sizing PHE by converting a transfer are to the HP nominal power can be applied both for monobloc and split types.
These are proven conversion factors that provide a healthy supply allowing for operation for many seasons (taking into account the aging of heat exchangers over the years), the use of glycol and the possibility of efficient operation with minimal temperature differences (i.e. minimal energy consumption as well as minimal wear of the heat pump itself). You can decide to reduce them on your own if there are objective reasons for doing so, such as water instead of glycol. However, while expecting the above benefits to be achieved, the above conversion factors should be taken into account. In case of doubt, you can also confirm the selection PHE by contacting the service of the manufacturer or distributor of HP.
If you have difficulties with the selection of a PHE for a heat pump - write to us