How loud is a heat pump?

It is known that heat pumps are energy savings devices and a cost-effective way to cut down your heating bills especially if you are using gas/diesel fired boilers or electrical heaters. Everyone is aware of the heat pump working and its cost benefits but not the noise made by the heat pump.

How loud is a heat pump? is one of the common questions we get from our clients (mainly from the hospitality sector).

Let’s dig into this and see if the heat pump is as loud as conventional heating systems.

Heat pumps produce noise while working due to their components. The noise level might be quite high, and this factor usually affects the decision when buying such devices. It is important to have an overview of how the system works, what the usual noises are.

Air source heat pumps have four main elements when working: a compressor, a condenser, an expansion valve, and an evaporator. Of these elements, the ones making more noise when running are the compressor and the fan. Fan noises depend on different factors: the fan model and its speed, the airflow, and the pressure flow.

The airflow depends on the heat exchanger since air produces an aerodynamic noise when it passes through it. The noise intensity varies according to design and air velocity. Pressure flow, instead, is related indirectly to the noise since an increase in pressure makes the noise decrease and vice versa.

However, noises can derive also from the impact that the gap between the temperature of the air outside the refrigerator with the one where the refrigerating cycle occurs, creates. This causes the water in the air to become denser and freeze in the heat exchanger. To guarantee the correct working of the heat pump, it is necessary to run the compressor in reverse for some time to eliminate the frost accumulated. This can produce a disturbing noise that may combine with the fan noises.

Water source heat pumps produce less noise, as they do not take the heat from the air, and they do not need a fan. Therefore, they are more silent. The picture below shows a scale of noises and their level in decibels.