Keeping tenants and building users warm: sizing heat pumps correctly

Andy Smith, National Sales Manager at Grant UK, on the importance of specifying the correct size heat pump.

The cornerstone of a successful heat pump installation is selecting the correct heat pump size. The output of a heat pump, measured in kilowatts (kW), denotes how much energy it can contribute to a heating system. If the heat pump fitted is undersized, it will not produce sufficient heat output to fulfil the requirements of the home. If the heat pump fitted is oversized, it is likely that the system will not be as efficient as one that has been correctly sized and designed.

This variability underscores the necessity for a methodical approach to heat pump selection, established on a comprehensive understanding of the property’s specific heating requirements. Grant UK’s range of air source heat pumps has a series of outputs available including smaller, single fan units (including the Aerona³ R32 6kW heat pump and 10kW heat pump) through to larger heat pump models which have a twin fan (for example Grant’s Aerona³ R32 13kW air source heat pump and 17kW heat pump).

The Aerona³ 6kW ASHP is a small unit with a very compact footprint and it is ideally suited to homes which have a low heat loss, low space heating and hot water demand. The Aerona³ 10kW also has a compact footprint and can fulfil the heating requirements for medium-sized properties or properties where the insulation levels are adequate but maybe not as well insulated as a new build for example. The 13kW model is well suited to larger properties or households which have a larger demand for space heating and hot water while the 17kW model is often installed in large homes or small commercial buildings.

Conducting a heat loss calculation

At the heart of determining the appropriate heat pump size is a heat loss calculation. This process delves into various property aspects, including size, insulation efficacy, window configurations and geographical positioning, to ascertain the net heat loss during the coldest periods. It is a pivotal step that ensures the selected heat pump is fully capable of compensating for the heat loss, thereby guaranteeing a consistently comfortable indoor climate.

This evaluation is particularly crucial for social housing and local authority buildings, which often present a wide array of architectural styles and ages, from older properties to contemporary, energy-efficient designs. The selection process is influenced by several critical factors:

  • Building size and layout: The spatial dimensions and architectural layout play a foundational role in determining the heating load, with larger, open-plan spaces often necessitating higher output units.
  • Insulation: The level of insulation significantly impacts heat retention capabilities. Better-insulated homes can generally make do with smaller heat pumps, owing to their reduced heat loss.
  • Local climate: Geographic climatic conditions dictate the heating demands, with colder regions requiring more robust heat pump solutions to ensure comfort through the winter months.
  • Occupancy and lifestyle: The number of inhabitants and their lifestyle choices, including preferred indoor temperatures and occupancy schedules, may also directly influence the required heat pump size.

Smart controls

Smart controls are available for heat pumps which enable remote operation. Not only that, many controls have diagnostic capabilities too, alerting homeowners, installers and engineers to any issues with the heat pump, which can prevent minor problems from escalating into major repairs.

This predictive maintenance can help ensure the longevity of the equipment, potentially saving money and reducing environmental impact over time. For installers, these features can also open up new business opportunities – moving from a reactive heat pump servicing model to a more proactive one. By offering remote diagnostics and maintenance, installers can potentially reduce physical visits, optimise their schedules and provide a higher level of service.

The Aerona Smart Controller also comes with a WiFi Hub and once installed, an accompanying app and supporting web portal can provide remote access to the controller, as well as visibility of error codes and diagnostics information to assist with remote system support.

In addition, the controller is also compatible with both wired and wireless thermostats, enabling precise temperature control for individual heating zones.

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