Heat Pump Capacity for a Pool – How to Choose It
The capacity of a pool heat pump is chosen according to the volume of water. For each model the manufacturer states a maximum volume, and for a pool close to that limit the more powerful model is the better choice. This way the heat pump capacity remains sufficient even on cool days, when efficiency drops. In addition, the filter pump must provide the required flow rate.
In short:
- The heat pump is chosen by the pool volume, which is stated on each model’s page.
- When the volume is close to the upper limit of a model, choose the more powerful model.
- The heat pump works most efficiently at an air temperature of 15 °C and above.
- The filter pump must provide at least the minimum water flow rate of the heat pump.
- The heat pump is connected after the filter and before the water treatment systems.
How do you choose the heat pump capacity according to the pool volume?
The capacity is chosen by the pool volume: every model has a stated maximum water volume. Calculate the pool volume in cubic metres and find a model whose limit is above it. The volume formulas are in the article on calculating pool volume.
At Baseini.NET we offer POOLSANA inverter heat pumps and Azuro models. Here is how some of them compare.
| Model | Heating power | Suitable volume |
|---|---|---|
| POOLSANA InverPRESTIGE 9 | up to approx. 9.02 kW | up to about 35 m³ |
| POOLSANA InverPRESTIGE 11 | up to approx. 11.18 kW | up to approx. 45 m³ |
| POOLSANA InverPRESTIGE 15 | up to approx. 15.05 kW | up to approx. 60 m³ |
| POOLSANA InverPRESTIGE 18 | up to approx. 18.02 kW | up to about 70 m³ |
| Azuro BP-120HS | 12 kW at 20 °C | 65–95 m³ |
All models are in the pool heat pumps category. The price of each model is shown on its page.
Why is it good to have some power reserve?
A power reserve is needed because the stated volume for each model is indicative. In the description of POOLSANA InverPRESTIGE 11 the volume is given with a certain margin. If the pool is close to the upper limit, a more powerful heat pump is recommended. This way the heat pump capacity also covers the cooler days.
The reason is the air temperature. Below 25–27 °C the heat pump works at lower efficiency. The more powerful model keeps a reserve precisely for such days.
What is the role of air temperature?
The air temperature determines how well the heat pump works. Heat pumps work most efficiently at an ambient temperature of +15 °C and above. At air temperatures below 15 °C the coefficient of heat produced drops sharply.
That is why a heat pump with a capacity reserve is the safer choice for cool days. Heat pumps almost double the length of the season, and even more for covered pools. POOLSANA InverPRESTIGE 11 has an operating range from -7 °C to +43 °C.
What flow rate should the filter pump have?
The filter pump must provide at least the minimum water flow rate of the heat pump. For POOLSANA InverPRESTIGE 11 the minimum flow rate is 4.9 m³/h. For optimal operation, a flow rate about 1–2 m³/h higher than the minimum is recommended.
At a lower flow rate the efficiency of the heat pump may drop and heating may be weaker. Azuro BP-120HS requires a sand filter with a capacity of no less than 6 m³/h. If your filter is not sufficient, take a look at pool filter pumps.
How is the heat pump installed on the pool?
The heat pump is connected to the pool’s filtration system via a bypass. The installation sequence is as follows.
- Place the heat pump in its location and provide a protected power outlet.
- Connect the inlet and outlet of the heat pump to pipes with a diameter of 50 mm.
- Install the heat pump after the filter and before the water treatment systems.
- Switch on the filter pump and check that water circulates through the heat pump.
POOLSANA InverPRESTIGE 11 requires an outlet with a 16 A fuse and residual-current protection. Azuro BP-120HS and its outlet must be at least 3.5 m from the pool wall, and the electrical system must have protection of up to 30 mA. Before installation, check that your electrical system is in good working order.
Is the heat pump suitable for salt water?
POOLSANA InverPRESTIGE 11 is suitable for chlorinated water and for pools with salt electrolysis. Its titanium heat exchanger tolerates salt up to 0.5% (5 g/l). This concentration must not be exceeded, even briefly.
For how much salt to allow for in the pool, see the article how much salt to add to a pool. And for the cold season it is also worth reading about the winter pool cover.
Frequently asked questions
What heat pump capacity is needed for a pool?
The required heat pump capacity depends on the pool volume. Choose a model whose maximum volume is above the volume of your pool. For a pool close to the upper limit, choose the more powerful model.
Can a heat pump be more powerful than needed?
Yes, a power reserve helps on cool days. Below 25–27 °C the heat pump works at lower efficiency, so the reserve is not superfluous. The model’s volume is indicative and is given with a certain margin.
At what temperature does a heat pump work best?
The heat pump is most efficient at an air temperature of +15 °C and above. Below 15 °C the coefficient of heat produced drops sharply. That is why on cool days you need a power reserve.
Does the filter pump matter when choosing a heat pump?
Yes, the flow rate of the filter pump must cover the minimum of the heat pump. For POOLSANA InverPRESTIGE 11 the minimum is 4.9 m³/h. A flow rate 1–2 m³/h higher is recommended.
Can the heat pump be controlled from a phone?
Yes, POOLSANA InverPRESTIGE models have WiFi and a free smartphone app. This lets you set the heat pump locally or remotely. Azuro BP-140HS also has Wi-Fi control.
