Daikin 3MXM40A8 4.0kW Multi-Split Outdoor Unit (3 Room Connection)

Daikin 3MXM40A8 4.0kW Multi-Split Outdoor Unit (3 Room Connection)

The Daikin 3MXM40A8 is a compact multi-split outdoor condensing unit with 4.0kW nominal capacity, designed to run up to three indoor units independently from a single outdoor condenser. Using R-32 refrigerant and Daikin's swing compressor technology, it delivers efficient, low-noise operation from a single external installation point — ideal where outdoor space or planning restrictions limit the number of condensers that can be sited.

Supplied as the outdoor unit only, ready for connection to up to three compatible Daikin Perfera indoor units (FTXM, FVXM or CVXM series) by an F-Gas certified installation company.

Key Features

• 4.0kW nominal outdoor unit capacity
• Connects up to 3 indoor units, each individually controllable
• A+++ cooling energy label
• R-32 refrigerant — 68% lower GWP than R-410A
• Swing compressor design for low noise and high efficiency
• Inverter-driven compressor for continuous capacity modulation
• Operating range: cooling -10°C to 46°C DB / heating -15°C to 18°C WB
• Compact footprint: 552 × 852 × 350 mm

Benefits

• One outdoor unit, multiple rooms — connect up to three indoor units to a single outdoor condenser, reducing the number of external units needed on a wall, roof or courtyard.
• Independent room control — each connected indoor unit operates independently, with its own temperature and mode settings.
• Lower environmental impact — R-32 refrigerant significantly reduces the global warming potential compared to older refrigerants.
• Flexible installation — suited to properties where multiple rooms need air conditioning but outdoor unit space or aesthetics are a constraint.

Suitable Applications

• Multi-room residential installations (up to 3 rooms)
• Apartments and townhouses with limited outdoor unit space
• Small offices requiring independent zone control
• Retrofit projects where a single condenser location is preferred

Technical Specifications

Room Size Guide

As an outdoor multi-split unit, the 3MXM40A8's 4.0kW total capacity is shared across the connected indoor units, so actual room sizing depends on the combination of indoor units selected (for example 2 × 2.0kW or a 1.5kW + 2.5kW split). As a general guide, allow the combined nominal capacity of the connected indoor units to sum to no more than 4.0kW for optimal performance, and consult a heat load calculation for larger or unusually specified rooms.

What's Included

• Daikin 3MXM40A8 outdoor condensing unit
• Manufacturer documentation

Indoor units, pipework, brackets and installation materials are sold separately.

Recommended Installation Accessories

To complete the installation, your engineer will typically require the following — all available from Airconspares:

• Pair coil — pre-insulated refrigerant pipework in the correct diameter for each connected indoor unit (1/4" liquid / 3/8" gas per port)
• Wall brackets or ground mounting feet — for secure outdoor unit installation (36kg unit weight)
• Anti-vibration mounts — to reduce structure-borne noise from the outdoor unit
• PVC trunking — to protect and conceal pipework and cables on the external wall
• Condensate pumps — one per indoor unit, where gravity drainage is not available
• Local isolator switch — required by Part P of the Building Regulations
• Interconnecting cable — per connected indoor unit, sized to the installation manual

Pipework Installation Bundles

This system requires 1/4" liquid and 3/8" gas line copper pipework per connected indoor unit. We offer pre-matched installation bundles containing Lawton ACR copper coil, Armaflex EVO insulation, forged brass flare nuts and a Mastercool flaring tool — everything your engineer needs for each pipe run, in one order:

• AC Copper Pipe Installation Bundle — 1/4" — liquid line (6.35mm) | available in 6m, 15m & 30m
• AC Copper Pipe Installation Bundle — 3/8" — gas line (9.53mm) | available in 6m, 15m & 30m

Frequently Asked Questions

Does this listing include indoor units?
No. This listing is for the 3MXM40A8 outdoor unit only. Compatible Daikin Perfera indoor units (wall mounted, floor standing or other) are sold separately — select up to three to connect.

How many indoor units can I connect?
Up to three, each individually controllable, provided the combined nominal capacity of the indoor units does not exceed the outdoor unit's rated output.

Does this system include installation?
No. This listing is for the equipment only. Installation must be carried out by an appropriately F-Gas certified installation company.

Does this unit include refrigerant?
The outdoor unit is factory charged with 0.88kg of R32 refrigerant. Additional refrigerant may be required depending on total pipe run length, in accordance with the installation manual.

What refrigerant does this system use?
R32. This is a lower global warming potential refrigerant compared to R410A. Handling requires F-Gas certification.

Can this system heat as well as cool?
Yes. The 3MXM40A8 operates as a reverse-cycle heat pump, providing both cooling and heating to all connected indoor units.

What pipe sizes does this system require?
1/4" (6.4 mm) liquid line and 3/8" (9.5 mm) gas line per connected indoor unit port.

What is the maximum pipe run length?
20 metres chargeless per port, with a maximum vertical rise of 15 metres. Refer to the installation manual for full multi-port piping rules.

Is a local isolator required?
Yes. A local isolator switch is required by Part P of the Building Regulations and should be installed by a qualified electrician.

Professional Installation Required

This air conditioning outdoor unit must be installed and commissioned by an appropriately F-Gas certified installation company. Installation, pipework, electrical connection and commissioning are not included in this listing unless separately agreed in writing. Handling of R32 refrigerant requires appropriate F-Gas certification under UK F-Gas Regulations.

Manufacturer Resources

For full manufacturer documentation, visit the official Daikin 3MXM-A8 page.