Daikin Multi+: heat pump air conditioning with hot water

A Daikin Multi+ is one outdoor unit that heats rooms, cools them in summer and produces domestic hot water, with a tank indoors. Daikin describes it as a heat pump system that looks after heating, cooling and hot water from a single outdoor unit, connecting up to four indoor units and a hot water tank¹. It is an air-to-air system, so rooms are warmed and cooled by air, not by radiators or underfloor pipework.

The efficiency figures are strong on paper: up to A++ for heating, A+++ for cooling and A+ for domestic hot water¹. The Multi+ arrived in the UK in 2024, and the range has since grown to include 6.8kW and 9.0kW cooling capacities with 8.60kW or 10.00kW heating³. Tank options are 120L and 230L, with the 120L tank reaching up to 75°C and the 230L up to 65°C⁵.

It suits smaller properties. Daikin's own case studies describe it as designed for flats and small terrace homes, and one UK installation replaced a warm air system and a gas boiler in a five-unit set-up⁶. What it does not do is remove a household from electricity: the outdoor unit runs on mains power, and the app features depend on broadband and Daikin's servers.

What the Multi+ is: heating, cooling and hot water from one outdoor unit

The Multi+ is a multi-split air-to-air heat pump with a hot water cylinder added to the circuit. Daikin's wording is that it goes beyond heating and cooling, providing domestic hot water using the same outdoor unit⁴. The outdoor unit sits outside; the indoor units are wall-mounted, floor-standing or ceiling models, and the tank is a separate cylinder inside the home⁸.

That combination is unusual in the UK. Most air-to-air systems heat and cool only, leaving hot water to a boiler, an immersion or a separate cylinder. The Multi+ folds the third job into the same outdoor unit, which is why Daikin markets it as one system rather than three appliances⁷. The company also notes that in summer, solar energy heats the water while the house is being cooled, and that in winter the heat pump heats rooms and provides hot water at any time¹.

For a household, the appeal is space and simplicity: one outdoor unit instead of a boiler flue, a cylinder cupboard and a separate air conditioning condenser. The trade-off is that the system is air-to-air, so there is no wet central heating circuit to reuse. Existing radiators and pipework are not part of the Multi+ design. Households weighing that choice against a conventional wet system can compare it with air-to-air heat pumps and air-to-water heat pumps.

How the system is configured: indoor units, tank sizes and zones

Daikin's product pages describe one outdoor unit connected to up to four indoor units and a hot water tank¹. Other pages put the limit at three indoor units plus the tank, and the multi-split range generally allows up to five indoor units on one outdoor unit⁹. The figures differ by model and by page, so the practical answer is three or four rooms plus hot water, confirmed against the specific outdoor unit.

Each indoor unit can be controlled individually, and the system integrates multiple indoor units so different zones can be held at different temperatures¹. Indoor units of different types and colours can be combined to match each room, and more can be added later to the same outdoor unit².

Tank size is the decision that shapes daily life. A 120L cylinder suits one or two people; a 230L cylinder suits a larger household or one that uses a bath. The 230L tank is 1855 mm tall, so it needs a cupboard or utility space with real headroom. Daikin also lists 120L compatibility on some pages, which suggests the smaller end of the range is aimed at flats⁹.

Efficiency ratings: A++ heating, A+++ cooling, A+ hot water

Daikin states the Multi+ reaches up to A++ efficient heating, A+++ cooling and A+ rated hot water efficiency¹. A July 2025 press release repeats the same three ratings: A+++ for cooling, A++ for heating and A+ for domestic hot water⁸. The wider multi-split range is described as up to A+++ in both heating and cooling, and Daikin's general guidance says its units are rated up to A+++ for heating and cooling on a scale running from A+++ down to D⁴.

The gap between the Multi+ heating figure (A++) and the wider range (A+++) is worth noting. Adding a hot water cylinder to the circuit changes how the outdoor unit is loaded, and the Multi+ rating reflects that combined duty. The cooling figure stays at A+++ because cooling does not carry the cylinder load.

Efficiency ratings describe the appliance under test conditions, not the bill. How the system performs in a home depends on insulation, room sizes, how many indoor units run at once and what temperature the household asks for. Daikin's own case studies give a sense of real operation: one states the Multi+ system converts roughly 1 kilowatt of electricity into 3 or 4 kilowatts, and another reports a new installation drawing about 2.7 kilowatts¹². Those are single installations, not averages, and Daikin publishes no seasonal performance figure for the Multi+ in UK homes. Households wanting the wider picture can read heat pump efficiency: COP, SCOP and SPF explained.

Hot water operation: scheduling, simultaneous heating and the POWERFUL button

Daikin states plainly that rooms and hot water can be heated simultaneously, and that water can be heated on a schedule or when the air conditioning is off¹. That matters in a flat where cooling and hot water might otherwise be thought to compete. The company also notes that if the air conditioning is on, pre-heated hot water is still available, and that in winter the heat pump heats rooms and provides hot water at any time¹.

When demand runs ahead of the schedule, there is a manual override. Daikin's instruction is to activate the POWERFUL button on the domestic hot water tank, and the water will be re-heated¹. The all-year comfort page puts it more simply: if more hot water than usual is needed, one press of POWERFUL tops it up¹⁵.

Daikin describes four operating modes to balance ambient temperature control and hot water¹. The system is designed so that the cylinder is not simply a slave to the heating circuit: it has its own schedule and its own boost. For a household, that means hot water can be timed for a morning shower and a evening bath without the rooms being held at temperature all day to make it happen.

Noise: night quiet and quiet operation modes

The Multi+ carries Quiet Mark listings for several outdoor unit models, including the 4 port 4MWXM52A9, the 4 port 5MWXM68A9 and the 5 port Class 90 5MWXM90A9¹⁶. Quiet Mark is an independent certification, and Daikin's brand page lists these alongside its air purifiers¹⁸.

Two noise modes are described on the certification pages. The outdoor unit has a night quiet mode setting to reduce sound pressure during the night, and the indoor unit has a quiet operation mode that reduces sound pressure by reducing the airflow rate¹⁶. Both are settings rather than guarantees: the outdoor unit still runs, and the indoor unit moves less air when quiet mode is on.

Daikin's Stylish indoor unit, which can be paired with multi-split outdoor units, is described as Quiet Mark certified with whisper-quiet operation down to 19 dBA¹⁹. That is an indoor unit figure, not an outdoor one, and it applies to that specific model. Outdoor unit noise is the figure that matters for neighbours and for planning, and it varies with the model and the mode selected. Households in England, Scotland, Wales and Northern Ireland face different planning and noise rules, covered in MCS 020: the heat pump noise assessment and how noisy is a heat pump.

Operating range and capacity: down to -15°C heating, up to 46°C cooling

The Multi+ outdoor units are listed with an operating range down to -15°C in heating and up to 46°C in cooling⁸. Daikin's multi-split catalogue gives the same heating floor of -15°C and a cooling range up to 46°C across the multi-split outdoor units²¹. That heating range covers UK winter conditions in most of the country, and the cooling range covers anything a British summer is likely to produce.

Capacity figures come from the July 2025 press release. The Multi+ is available with a nominal capacity of 6.8kW or 9.0kW in cooling and 8.60kW or 10.00kW in heating⁸. The smaller 4 port system was launched the year before that release, and the current range consists of three models including a 4 port 5.2kW unit, plus 120L and 230L cylinders⁸.

The press release positions the larger capacities as ideal for larger domestic and light commercial applications⁸. That is a shift from the original smaller-property focus, and it means the range now spans a one-bedroom flat to a larger house or a small business premises. Households should note that capacity figures are nominal ratings, not a room-by-room heat loss calculation, and that the number of indoor units running at once affects what the outdoor unit can deliver. Sizing is covered in heat pump sizing and heat loss calculations.

Control and monitoring: the Daikin Onecta app and the tank display

Control runs through two routes. The Daikin Onecta app allows heating and hot water to be controlled from a smartphone, and Daikin states it can control the system remotely, even when away²². The app is available for iOS and Android and can centrally control up to 50 units at once²³. Each indoor unit can be controlled separately through the same app².

The second route is local. The Multi+ cylinder has an intuitive full-text display for monitoring and adjustment of all settings, including scheduling and water temperature⁹. That display works without a phone, a broadband connection or a Daikin account, which matters if the internet goes down or the household prefers not to rely on an app.

Adding a second property or a second system to the same account is possible. Daikin's support guidance describes enabling Out-of-home operation on a unit and being prompted to copy the settings of another unit's Out-of-home account, with the steps run from the app's adapter settings²⁴. That is a convenience for households with more than one Daikin system, not a requirement for a single installation. The wider picture on controls is at heat pump controls, weather compensation and smart operation.

Where Multi+ fits: smaller properties, flats and real UK installations

Daikin describes the Multi+ as designed for smaller properties, like flats and bijou terrace homes, offering heating and cooling⁶. One installer quoted in a Daikin case study calls it perfect for flats or one and two-bedroom houses, with one small outdoor unit providing water, heating and cooling⁶. The multi-split range generally is described as easy to install with minimal outdoor space required, and indoor units of different types and colours can be combined to match every room².

Real UK installations show what that looks like. At a Folkestone property, a five-unit Multi+ system with a 230L cylinder replaced a Johnson & Starley warm air system and a Potterton gas boiler, installed in October 2025⁷. The cylinder went in the garage, connected to one indoor unit, while the other four units served the lounge and three bedrooms⁷. That is a five-indoor-unit installation, above the four-unit figure on the product pages, which shows the configuration depends on the outdoor unit chosen.

A Weybridge terrace case study describes the Multi+ as a newly launched system for smaller properties, and a Blue Water case study states the Multi+ only came to the UK recently, in 2024⁶. The press release's move to larger capacities suggests the range is broadening beyond that original brief⁸.

For energy independence, the position is mixed. The Multi+ produces hot water from the same outdoor unit that heats and cools, so it removes a gas boiler and a gas supply from the hot water and space heating side. It does not remove electricity: the outdoor unit, the indoor units and the cylinder controls all run on mains power, and the household remains on a electricity supplier and the grid. The app adds a dependence on broadband and on Daikin's servers for remote features. Households wanting the wider context can read heat pumps and household energy independence and air-to-air vs air-to-water heat pumps.