How to choose a heat exchanger

How to choose one heat exchanger with plates for connecting heat pump to the heating system
Heat pumps as a heating device represent a rather demanding solution in terms of heat exchange, which translates into the objective need to select a heat exchanger with a larger surface area than, for example, for classic thermal power plants of similar power. The reason is both the fact that they usually operate at much lower deltas, and the desire to ensure that the heat pump operates with as low an energy consumption as possible, as a rule.

Below we present a number of types of heat exchangers and recommendations on how to choose a heat exchanger, which are most often sold for heat pumps. Of course, this concerns the connection of the heat pump to the installation, in the water-water or water-glycol system, these are not freon exchangers or units for the so-called R-factors.

In the case of heat pumps, the selection of how to choose a heat exchanger depends not only on the nominal power of the heat pump, but also on the temperatures at which the central heating system is to operate. It is not about the maximum performance of the pump, but rather about the operating temperature that we expect from the pump so that it can provide thermal comfort at home. The smaller it is, the larger the heat exchanger will be required, but it is worth keeping it as low as possible due to the expected operating costs.

The plate heat exchanger for a heat pump must be sized according to the expected operating temperature of the pump.

The first case is a classic configuration – where radiators play the main role, and underfloor heating is possibly a supplement. In such an installation, the operating temperature of the pump must be at least approximately +50 °C for the radiators to work optimally. For such systems, approximately 1,50 m² of the heat exchange surface should cover each 10 kW of the heat pump (operating at 50°C).

The second case is represented by 100% heated installations with underfloor heating, where the pump operating temperature will only be required at the level of approximately +30 – +35 °CIn such cases, the heat pump operates very economically, but a relatively large heat exchanger system is required for efficient operation – the sizing converter here is approximately 3,0 m² of heat transfer surface for each 10 kW heat pump (operating at 35°C).

Intermediate options, i.e. feed temperatures of 40 or 45 °C, should be sized proportionally.

The heat pump sizing presented by converting a transfer area to the nominal heat pump power can be applied to both monobloc and split types.

These are proven conversion factors. They ensure a healthy and sustainable diet.
It allows operation for several 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 are taken into account.
This means minimal energy consumption, as well as reduced wear and tear on the heat pump.
You can decide to reduce these conversion factors on your own, if you have objective reasons — for example, if you use water instead of glycol.
However, even if you expect additional benefits, the above values ​​should still be considered.

In case of doubt, you can confirm the selection of the heat exchanger (PHE) by contacting the technical service ALTAL from Romania, ALTAL from Moldova or your local heat pump dealer.

Contact ALTAL technical support. If you have any difficulties choosing a heat exchanger for a heat pump, write to us.