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The ZEB is designed to be highly tolerant of various heating system setups and controls. Compared to heat pumps or to a certain extent condensing boilers, the ZEB largely maintains consistent performance regardless of the heating system's complexity. However, optimising the ZEB setup can enhance your overall experience.
Setting the Water Flow Temperature Setpoint
The water flow temperature setpoint determines the temperature of the water circulating through your radiators. By default, the ZEB is preset to 70°C upon delivery, but you can adjust this setting between 35°C and 80°C via the mobile app (under the ZEB Settings menu).
Effects of Different Setpoints:
- Higher Setpoint (e.g. 80°C)
- Radiators heat up quickly, warming the house faster.
- Residual heat continues to be emitted after the thermostat stops calling for heat, causing air temperature fluctuations that may be uncomfortable.
- Lower Setpoint (e.g. 55°C)
- It takes longer for the house to reach the desired air temperature.
- Provides a more stable and comfortable indoor climate with fewer temperature swings.
Efficiency
Whereas running a heat pump or condensing boiler at lower flow temperatures impacts efficiency, this isn’t the case for the ZEB. One key advantage of the ZEB is that its efficiency is largely unaffected by the water flow temperature setpoint. Running the internal air fan at maximum speed uses only a tiny bit more power than at minimum speed, meaning the efficiency and cost of operating the ZEB remain essentially unaffected, regardless of how hard it is working.
Whether you set a high or low temperature, the energy required to raise the air temperature from 18°C to 21°C remains the same. The difference lies in how quickly the heat is transferred and distributed. At the lowest flow temperature setpoint (35°C), radiators may feel cool to the touch, yet they still heat the room gradually by maintaining a temperature above the surrounding air temperature.
Noise
The noise level of the ZEB depends largely on its installation location and when the thermostat calls for heat. If installed near living spaces, the ZEB’s internal air fan may be noticeable, especially upon startup. However, once the flow temperature reaches its setpoint and the air fan slows down, the ZEB is essentially silent. This startup noise is comparable to a traditional gas boiler, though without the characteristic ‘whoosh.’
An additional benefit of lower flow temperature settings is reduced pipe noise. Traditional gas boilers often cause pipes to creak and groan as they heat up and cool down. By contrast, the ZEB operates more smoothly, significantly reducing these noises.
Important Considerations
- If you reduce the flow temperature setpoint, consider extending the thermostat timer to allow more time for heating.
- If your ZEB is connected to a hot water cylinder for baths or showers, do not set the flow temperature below 60°C to mitigate the risk of Legionella bacteria growth.
By carefully adjusting your ZEB’s flow temperature setpoint, you can achieve a balance between comfort and optimal performance for your home heating needs.