Mærskgaarden residential community
Plug-and-play heat pump for communal heating
The heat pump is enclosed by sound panels.
Mærskgaarden residential community has replaced
gas boilers with a heat pump.
The case
Mærskgaarden is a residential community with 82 senior housing units on the island of Tåsinge in Denmark. Like many smaller residential sites, it previously used gas boilers for heating. Now, the community has fully electrified its heating supply, with Fenagy delivering a robust, plug-and-play heat pump.
The system centres on an H-300 air-to-water heat pump using CO₂ as refrigerant. With a capacity of 300 kW, it supplies heating to the 82 homes in combination with a 350 kW electric boiler and a 4.5 m³ accumulation tank, enabling 100% fossil-free heating. The heat pump can support system balancing and price-optimised operation, but as this was not part of the business case, a small buffer tank was installed to provide stable operation, rather than fully decoupling production from demand.
The heat pump is installed outdoors on a concrete foundation and enclosed by sound panels to minimise noise. Although the unit itself operates at a low noise level, additional sound insulation was required due to its location close to a residential area with very strict noise limits.
On-site installation is simple: an electrician connects the cables, a plumber connects the pipes, and the system is ready to run shortly after delivery.
Year: 2025
Model: H-300 close coupled, air-to-water
Capacity: 0.3 MW · 40°C/70°C
return/flow (5°C/85% humidity)
Refrigerant: CO₂ (R744) - natural, non-toxic, non-flammable
Defrost: Cold gas
Close-coupled heat pump and V-shape evaporator
(energy collectors) installed inside a sound enclosure.
Delivery on site. The close-coupled heat pump is here installed
on a concrete foundation.
The heat pump
The Mærskgaarden installation features Fenagy’s H-300 close-coupled heat pump in a sleek new design. The system is delivered as a compact, plug-and-play unit on a single steel frame: at one end is the heat pump module housed in an enclosure with integrated control systems, lighting, ventilation and sound insulation, and the energy collectors are mounted directly next to it on the frame.
The H-300 uses CO₂ as a natural refrigerant and can deliver hot water up to 85°C. It has a robust cold gas defrost system, which has been refined and optimised for the V-shape solution over three winter seasons on four similar heat pumps. This experience has now been incorporated into an enhanced PLC programme and implemented in the upgraded H-300 CC unit, ensuring stable operation even under harsh winter conditions.
The close-coupled design is also available as a chiller or combined heating/cooling system, typically used in industrial settings or for communal and district heating. It’s a practical, scalable solution that supports affordable and sustainable energy supply.
At Mærskgaarden, the system contributes to the green transition and ensures stable indoor temperatures year-round – all in a streamlined, space-saving and low-noise setup.
The close-coupled heat pumps and chillers are plug-and-play solutions delivered on a single steel frame
with the heat pump/chiller in an enclosure at one end and energy collectors or a gas cooler at the other.
Available with capacities from 300-600 kW. The heat pump can deliver supply temperatures up to 85°C.