Technical Support for Air Source Heat Pumps

Heat pumps will work at around -15ºC to -20ºC however a heat pump works best when the temperature is above 3 ºC or 4 ºC. When the temperature drops below 3 ºC, heat pumps operate less efficiently and will consume more energy.

During winter months when it is particularly cold, condensation can form and freeze on the finned evaporator coil of the unit. It is a normal occurrence and the heat pump is designed to cope with this. The control system will detect when the coil has iced up and will automatically enter a ‘defrost’ cycle. During this short ‘defrost’ period the fan will stop and the heat pump will cease supplying heat to the heating system in order to melt the ice. On completion the fan and heat pump will automatically restart and resume supplying heat to the heating system. This will not adversely affect the building temperature.

Grant’s Aerona³ air source heat pumps feature an in-built 'Defrost' function which automatically operates to assist the heat pump when external temperatures drop below 0˚C. In brief, the defrost cycle reverses the heat pump's operation to direct hot refrigerant vapour back into the ice covered evaporator causing any ice to melt.

The SCOP means Seasonal Coefficient of Performance which is a way of measuring the true energy efficiency of heating and cooling technology over an entire year. This measure gives a more realistic indication of the energy efficiency and environmental impact of a system. This is indicated as a ratio for energy required to run the heat pump compared to the amount of energy being produced by the heat pump for typical day to day use. A heat pump with a SCOP of 4 means that for every 1kW of energy used to run the heat pump, 4kW will be produced.

Weather compensation is a way of modifying the heating system output according to the temperature outside by simultaneously monitoring indoor and outdoor temperatures. The water used to heat your property within the heating system will become hotter if the outside temperature declines, and vice versa.

Weather compensation regulates and maintains an optimum flow temperature which can help prevent changes in the heat pump’s functioning. It prevents the appliance starting up or shutting off when a property is too hot or too cold.

Using both weather compensation and setback controls at the same time can be considered counterproductive. Click the 'Read more' link below to learn more about the recommended setup for setback controls and weather compensation.

The flexible hoses on a Grant heat pump should be checked with every service. If the flexible hoses are damaged or leaking, they should be replaced.

No, the Grant Aerona³ Remote Controller must not be fitted inside the heat pump casing. It should be installed in a convenient position where the end-user can easily access it to view the display and to operate the on/off switch when necessary. It is important to note that for MCS installations, it is a requirement that any fault indication (for example via fault error codes that display on the remote controller) is clearly visible to the user.

No, the Aerona³ Remote Controller should not be fitted outdoors next to the heat pump. This is because the remote controller is not waterproof. Instead, the remote controller should be installed inside in a convenient location where the end-user can easily access the unit and view the display.

Yes, the complete water circuit, including all pipework must be insulated to prevent heat loss reducing the efficiency of the heat pump and also to prevent damage due to frozen pipes.

Yes, the external flexible hoses connected to an air source heat pump must be insulated. This is required to reduce heat loss and to prevent damage due to frozen pipes.

Normal domestic heating controls, such as a 2-channel programmer, room thermostat and cylinder thermostat are suitable for use with Grant air source heat pumps.

Use a dedicated power supply with a correctly sized circuit breaker. The final power supply connection must be made from a weatherproof lockable isolator located outside the building. The cable should be either armoured or run in a flexible conduit between the isolator and heat pump.

Unit                   Power Supply Cable (mm²)                     Breaker Type and Capacity

HPID6R32                       4.0 - 2.5                                                   16Amp Class C

HPID10R32                     4.0 - 2.5                                                   20Amp Class C

HPID13R32                     6.0 - 4.0                                                   32Amp Class C

HPID17R32                     6.0 - 4.0                                                   32Amp Class C

Should the installer wish to extend the control cable from controller to unit, then they can use standard CAT 5 cable.

The Grant Combined Volumiser/Low Loss Header is designed for installation with the Aerona³ air source heat pump, and it serves as a volumiser and hydraulic separator.

The refrigerant in an air source heat pump should not require replacing unless a leak is detected. If, during the annual service for example, a refrigerant leak is identified, this can only be remedied by a qualified engineer. Under no circumstances should the refrigerant be vented from the charging points on the refrigerant circuit of the heat pump and if any work is required to be carried out on the refrigerant circuit it MUST be undertaken by an F-GAS Registered Engineer.

Grant’s Aerona³ R32 generation of air source heat pumps uses R32 refrigerant which has a GWP which is considerably lower than heat pump refrigerants such as R410. In addition to having a lower GWP figure of 675, R32 is a single-component refrigerant which means it has no temperature glide. Refrigerant blends that have two or more components exhibit temperature glide but as R32 only has one molecule in its formation, its saturated liquid and vapor temperatures are the same. By removing the risk for the refrigerant to suffer from glide, the system can recharge and recycle with greater ease, making it more efficient.

Annual servicing is recommended for Grant heat pumps. The servicing and maintenance of an air source heat pump should be carried out by a competent heating engineer in line with the instructions provided in the Installation and Servicing Manual. Regular servicing of a heat pump system can help ensure the longevity of unit and aid their performance and reliability year after year.

No specific qualifications are required to fit an air source heat pump but it is strongly recommended that heating engineers undertake the relevant product training prior to completing their first heat pump installation.

No, an air source heat pump cannot be installed indoors. They need to be sited outdoors with a clear, unobstructed airflow in order to work. You can learn more about how an air source heat pump operates here.

Yes, a heat pump is designed to be installed as part of a sealed heating system. All Grant Aerona³ heat pumps must be used with sealed systems that comply with the requirements of BS EN 12828, BS EN 12831 and BS EN 14336. The system must include a diaphragm expansion vessel complying with BS EN 13831, a pressure gauge, a pressure relief (safety) valve and an approved method for filling the system.

A Volumiser tank is required for all Grant Aerona³ R32 heat pump installations, except when the heat pump is connected to a Grant combined volumiser/low loss header, buffer or thermal store.

When installing an air source heat pump, a hot water cylinder that is compatible with heat pumps must be selected and, more often than not, an existing cylinder will not be suitable.

Yes, once you have installed an air source heat pump and the system has been commissioned, the local Building Control will need to be notified of the new installation. Notifying Building Control is the responsibility of the installing engineer. In addition, the local Distribution Network Operator (DNO) also needs to be informed of a new heat pump installation and this is also the responsibility of the installer - this either needs to be in the form of an application (before the heat pump installation commences) or a notification retrospectively (retrospective notification to the DNO is only possible for ‘Connect & Notify’ products such as the 6kW, 10kW and 13kW Aerona³ heat pumps and any of the Aerona 290 heat pump models supplied by Grant UK).

The typical life expectancy of an air source heat pump would be between 10-15 years, provided the unit is installed and commissioned correctly and regularly maintained with an annual service.

Yes, all models within the Grant Aerona³ range are MCS approved.

All of the Grant Aerona³ R32 air source heat pumps have been approved by CEN KEYMARK, an independent European certification mark for all heat pumps, combination heat pumps and hot water heaters.

The Aerona³ 6kW (HPID6R32), 10kW (HPID10R32) as well as the Aerona 290 4kW (HPR2904), 6.5kW (HPR29065) and 9kW (HPR2909)and 13kW (HPID13R32) air source heat pumps are Connect & Notify approved which means they can be installed and connected to the Grid without prior approval from the DNO which makes their installation even more straightforward.