Heat Pump Water Heaters

A heat pump water heater – also known as an exhaust air heat pump water heater – is an energy-efficient appliance that provides domestic hot water (DHW) by extracting renewable heat from the surrounding air rather than generating heat directly through electricity or gas combustion. Unlike traditional electric immersion heaters or gas water heaters, heat pump water heaters transfer heat from the air into stored water, achieving exceptional energy efficiency.

For example, Modutherm's Juniper HP Plus achieves a Coefficient of Performance (COP) of up to 4.09 and an A++ energy rating, meaning it produces over four times more heat energy than the electricity it consumes. This delivers significantly greater efficiency than conventional electric water heating systems and offers substantial reductions in both energy consumption and carbon emissions.

As building standards evolve towards low-carbon solutions, heat pump water heaters are becoming increasingly important for residential and commercial developments. They offer several key advantages:

Energy efficiency and cost savings: The Juniper HP Plus, with its COP of up to 4.09, delivers running costs approximately 70% lower than traditional electric immersion heaters. This translates to annual savings of hundreds of pounds per installation whilst reducing carbon emissions.

Future-proof technology: Heat pump water heaters align with the UK's net-zero targets and building regulations that increasingly require low-carbon heating solutions. They work particularly well in properties moving away from gas infrastructure or in developments designed without gas supply.

Natural refrigerants: The Juniper HP Plus uses R290 natural refrigerant with a Global Warming Potential (GWP) of just 3 and zero Ozone Depletion Potential (ODP), ensuring minimal environmental impact.

Space-saving design: Compact dimensions allow heat pump water heaters to fit within standard cupboard spaces, making them ideal for apartment buildings and properties where space is at a premium.

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Heat pump water heaters operate on the same thermodynamic principles as air source heat pumps but are specifically designed for domestic hot water production. The system consists of:

Air extraction: The unit draws air from outside or extracts waste heat from within the property via ducting. This exhaust air functionality makes them particularly efficient in commercial buildings, gyms, or spaces with mechanical ventilation.

Heat transfer: A refrigerant circuit absorbs heat from the air, compresses it to increase temperature, and transfers this heat to water stored in an integrated cylinder through a heat exchanger.

Storage and delivery: The heated water is stored in an insulated cylinder (the Juniper HP Plus is available in 200L and 300L capacities) and delivered on demand. Water temperatures of up to 60°C can be achieved using the heat pump alone, with an integrated 1.6kW electric backup heater available for boosting to 70°C when required for legionella protection.

Smart controls: The Juniper HP Plus features advanced control systems that optimise performance by automatically calculating operating conditions and adjusting power input to achieve maximum COP. Features include automatic anti-legionella cycles, smart home integration via WiFi and the Smart Life app, and remote connectivity.

The Juniper HP Plus range offers:

Cylinder capacities: 200L and 300L models, suitable for typical residential properties, apartments, and small commercial applications.

Hot water output: Under standard test conditions (EN16147), the units can deliver mixed water at 40°C volumes of 271 litres (200L model) and 383 litres (300L model), providing ample domestic hot water for family homes or multiple apartments.

Recovery times: Volume recovery times of 5.1-10 hours at standard conditions (A20/W55) ensure consistent hot water availability throughout the day.

Energy efficiency: The Juniper HP Plus achieves an A++ energy rating at higher ambient temperatures (A20/W55), with a COP of 4.09 delivering exceptional efficiency compared to conventional electric water heaters that operate at just 100% efficiency.

Heat pump water heaters are versatile solutions suitable for:

Apartment buildings: Particularly effective in apartment developments where individual properties require domestic hot water but space heating is provided separately through electric radiators or underfloor heating systems. The Juniper HP Plus, coupled with electric radiators, presents an efficient and cost-effective alternative to traditional heat network solutions.

New build developments: Properties designed without gas infrastructure increasingly specify heat pump water heaters as the primary DHW solution, especially when paired with renewable electricity from solar PV. The Juniper HP Plus is PV ready and listed in SAP Appendix Q.

Retrofit applications: Replacing old electric immersion heaters or removing gas appliances in properties transitioning to all-electric systems.

Commercial properties: Schools, offices, gyms, and leisure facilities benefit from exhaust air functionality, capturing waste heat from occupied spaces whilst providing dehumidification.

Social housing: Housing associations and local authorities specify heat pump water heaters to reduce energy bills for tenants whilst improving EPC ratings and meeting sustainability targets.

Heat pump water heaters are straightforward to install but require specific considerations:

Ducting: The Juniper HP Plus requires ducting to extract air from outside or from within the property. Each unit features a removable split top, allowing easy servicing without the need to detach ducting.

Electrical supply: Standard single-phase 230V connection with 13A fused spur. Maximum power consumption is 2.2kW including the backup electric heater.

Space requirements: Compact footprint makes installation possible in standard kitchen cupboards, utility rooms, or airing cupboards.

Plumbing connections: Standard ¾" BSP connections for cold water inlet, hot water outlet, and domestic cold water outlet.

Location flexibility: Indoor installation with front-access design allows servicing without removing ducting. The Juniper HP Plus is available in left and right-hand variants for flexible installation in prefabricated utility cupboards (PUCs) or apartment risers, with handed front/side-mounted water connections to facilitate straightforward integration with pipework.

Building integration: The Juniper HP Plus features Modbus connectivity, WiFi control via Smart Life app, and can integrate with photovoltaic systems for enhanced renewable energy utilisation.

For detailed specification and installation guidance, view our technical documentation or contact our technical team.