When hot water demand sets the specification

Domestic hot water places its own demands on the system. Two households with the same number of occupants can have very different requirements, depending on how and when they use hot water.

For installations where hot water demand plays a grater role, tank capacity, recovery and system configuration become important considerations.

The ES M 250L adresses these requirements. Part of the ES Energy Save residential R290 range, this 250-litre heat pump indoor unit combines domestic hot water storage, backup heating and system controls in one free-standing unit.

A system can meet a home’s heating requirements ans still fall short when it comes to hot water.

Household size is an obvious starting point, but usage patterns matter too. Two showers running at the same time create a different demand than when household members use hot water at separate times. The same applies when someone fills a bath while others use hot water elsewhere.

This is where tapping profiles become useful. Rather than simply stating tank size, the tapping profile provides a standardised measure of the hot water a system can deliver across a defined pattern of daily use.

In standard pairings, the ES M 250L achieves tapping profile L. Paired with the ES M15 R290 three-phase outdoor unit, it reaches tapping profile XL, the highest hot water delivery profile in the ES Energy Save residential range.

The ES M 250L has a 250-litre nominal domestic hot water tank, with a net capacity of 217 litres. But storage is only part of the equation. A 35-metre heat exchanger coil provides a surface area of 4.4 m², supporting efficient heat transfer and recovery as hot water is used.

The tank uses DUPLEX stainless steel and a SUS316 stainless steel coil. Both materials support long-term durability in domestic hot water applications.

Installers can pair the ES M 250L with any outdoor unit in the ES Energy Save residential R290 range. Compatible models include the ES M8 (8 kW), ES M12 (12 kW) and ES M15 (15 kW), in single- and three-phase configurations.

This becomes particularly relevant when a property combines higher heating requirements with higher hot water demand. The 250L provides the integrated tank option across the full residential output range.

The integrated format keeps the system together in one indoor unit, but there are a few practical considerations worth checking before delivery.

The ES M 250L requires a three-phase supply (380–415 V, 3P 16A) for its integrated 9 kW backup heater. This requirement also applies when the system uses a single-phase outdoor unit. Installers should therefore confirm the electrical supply early in the project.

At 127 kg net, the installation route should also be checked before delivery – including doorways and stairs, not only the final installation position.

A buffer tank is recommended, particularly for radiator systems and multi-zone installations.

Connectivity follows the same approach as the rest of the range, with Wi-Fi and wired connectivity, mobile app access and remote system management through ES Cloud and Fleet Manager.

Different installations have different priorities.

Where installation space is limited, the ES M 100L offers a compact, wall-mountable solution with integrated domestic hot water storage. Its design makes it particularly suitable for retrofit installations.

For installations with higher hot water demand, the ES M 250L provides greater storage capacity and compatibility with the full residential outdoor range, including the 15 kW units.

For installations that don’t require integrated domestic hot water storage, the ES MHB HydroBox and ES MCB Control Box offer alternative system configurations.

With the 100L, installation space often drives the decision. With the 250L, hot water demand becomes a more important consideration.

The ES M 250L is part of the ES Energy Save residential R290 platform, compatible with monobloc outdoor units from 8 to 15 kW. With a GWP of just 3, R290 offers a long-term alternative as European F-gas regulations progressively phase out higher-GWP refrigerants. This makes refrigerant choice another important consideration when specifying a heat pump system for the future.

Explore the ES M R290 residential range →

Read more: Why R290? The refrigerant shift that matters for your business →