Monobloc and split heat pump systems

A monobloc heat pump system is made up of a single unit heat pump that is located outside of the home, on a wall or are that has free air and maintenance access. This outdoor unit is draws heat or coolth from the outside air to heat or cool a home, it consists of the compressor, the heat exchanger and water side of the refrigeration cycle. In this system the entire process happens in the same unit with pre-heating occurring outdoors before moving inside to directly heat the house or with top up electrical heating.

In the newer split systems, a fan and condenser draws heat or coolth from the outside air, collecting and transferring the now pre-heated (or cooled) gas to another unit which is located inside the home. This secondary unit then transfers the heat from the compressed gas refrigerant to the water systems in the house where it is required or for storage, such as in a hot water cylinder. The newer split unit systems in general have the advantage of smaller outside units, that run more quietly and are often more efficient, however they are more complex and often more expensive to install than monoblock systems.

In September 2023 the UK government Department for Energy Security and Net Zero, Boiler Upgrade Scheme increased the grants available for UK households to install new systems. Acting on behalf of property owners, installers can apply for between £5,000 and £7,500 off the cost and installation of an air source heat pump, ground source heat pump (including water source heat pumps) or a biomass boiler (the lower amount). As of 2024 the status of the scheme remained as being a total of £450 million in grant funding available over the three years from 2022 to 2025.

In response to feedback and in relation to the efficiency points that are described above eligibility for the grant is dependent of the receipt of an Energy Performance Certificate (EPC) and were improved fabric performance is a recommendation given on the EPC, it must be carried out to a degree before the property is eligible to receive a BUS grant. Elements such as heat emitters with larger surface areas, to counter balance the often lower temperature outputs of heat pumps are not currently a stipulation in the government scheme but a consideration that lies with the system designer.

[edit] Related articles on Designing Buildings

• Absorption refrigeration.
• Air conditioning.
• Absorption heat pump.
• A decade for heat pumps.
• Air source heat pumps.
• BUS
• Chlorofluorocarbons CFCs.
• Domestic heat pumps and the electricity supply system.
• Dynamic thermal modelling of closed loop geothermal heat pump systems.
• Earth-to-air heat exchangers.
• Evaporative cooling.
• Exhaust air heat pump.
• Greenhouse gas.
• Heat pump COP & EER and central plant SCOP in ambient loops.
• Heat pumps and heat waves: How overheating complicates ending gas in the UK.
• Heat recovery.
• Hybrid heat pump electric panel heating.
• Hydrochlorofluorocarbons HCFCs.
• Latent heat.
• Mechanical ventilation with heat recovery.
• Montreal Protocol.
• Ozone depleting substance.
• Phase change.
• R22 phase out.
• R404A phase out.
• Refrigerant selection.
• Refrigerants in buildings.
• Refrigerants in building services guide TG 21/2022.
• Types of heat pump.
• Types of refrigerant.
• Variable refrigerant flow.