The Advantage of the 2.7 cm Flat Hose: Midea PortaSplit Hose Routing Guide

The defining physical characteristic of the Midea PortaSplit — and the feature that distinguishes it most sharply from every single-hose or dual-hose monoblock portable — is the flat hose assembly that connects its indoor evaporator section to the outdoor condenser module. Where a conventional portable air conditioner requires a 130–150 mm round exhaust hose and a corresponding 160 mm+ opening in a window panel, the PortaSplit's midea portasplit flat hose thickness of approximately 27 mm allows the entire refrigerant connection to pass through a window gap barely wider than a set of car keys.

What are the cross-section dimensions of the Midea PortaSplit flat hose?

The PortaSplit flat hose assembly measures approximately 27 mm in its thinnest dimension (the dimension that passes through the window gap) and roughly 80–90 mm in width. The 27 mm thickness is the defining figure: it represents the combined cross-section of both insulated refrigerant lines, the power and signal cable for the outdoor unit, and the outer insulating and protective jacket — all flattened into a single bundle that presents a minimal profile to the window opening.

Inside the flat bundle, the assembly contains a liquid refrigerant line (carrying high-pressure liquid refrigerant from condenser to expansion device, typically 6 mm outer diameter copper tube), a suction or gas line (carrying low-pressure refrigerant vapour from evaporator to compressor, typically 10–12 mm outer diameter with foam insulation to prevent condensation on the cooler suction gas), a power supply cable for the outdoor unit fan motor and electronics, and a signal communication cable between the indoor control board and outdoor unit. The entire assembly is wrapped in a flexible outer jacket that maintains the flat profile across its full length.

How does a 27 mm flat hose fit through a closed window gap?

A standard uPVC double-glazed tilt-and-turn window, when in tilt position (the top-hinged slightly open configuration standard in German and northern European housing), creates a gap of approximately 100–150 mm at the top of the frame. Closing the window from full-tilt to approximately 28 mm open is achieved by using the window's built-in tilt limiter or by manually holding the window at that position with a compression-fit foam wedge. The flat hose is then passed through this gap, compressed gently into the window seal, and the foam strip seal applied to complete the weather closure.

For standard casement windows (side-hinged), the procedure is identical but uses the side-hinge opening rather than the top tilt. The window is held at approximately 30 mm open using a window stay or friction limiter; the flat hose is routed through the gap at the hinge side; and a compression foam strip closes the seal. The key geometric advantage is that 27 mm is less than the sealing compression travel of most modern EPDM (ethylene propylene diene monomer — the synthetic rubber used in window glazing seals) window gaskets, meaning the hose compresses the existing seal rather than requiring additional sealing material.

The table makes clear that no competing portable AC hose type approaches the 27–30 mm window gap requirement of the PortaSplit flat assembly. The next closest competitor — a 50 mm slim hose — still requires nearly twice the window opening and typically needs a foam panel rather than a simple strip seal, reintroducing the deposit-risk and heat-leakage drawbacks of panel-based installations.

Why flat hose cross-section matters more than diameter for rental apartment routing

The critical measurement for rental apartment compatibility is not hose diameter but the thinnest dimension of the hose cross-section — the dimension that the window must open to. A flat hose with a 27 mm thin dimension and an 80 mm wide dimension can pass through a 28 mm window gap without any panel or large opening, even though its total cross-sectional area (approximately 2,160 mm²) is comparable to a 52 mm diameter round hose (cross-section approximately 2,120 mm²). Flatness rather than smallness is the architectural feature that enables minimal window opening.

What sealing methods maintain a weatherproof closure around the flat hose?

The standard sealing approach for the PortaSplit flat hose through a window gap is a 30–40 mm wide self-adhesive EPDM or neoprene closed-cell foam strip wrapped around the flat hose at the point where it contacts the window frame seal. The foam strip should be applied to the hose exterior, not to the window frame, so that removing the hose assembly takes all sealing material with it and leaves the window frame surface untouched. Foam density of 100–150 kg/m³ provides adequate weatherseal compression without requiring excessive closure force.

For installations where the window is held at 28 mm by a friction stay or window limiter, a secondary backup seal — a length of self-adhesive brush pile (the material used in sliding door draught excluders, available from hardware stores in 5–10 mm pile heights) — can be pressed along the remaining gap length above and below the hose to prevent insect ingress and reduce summer warm-air infiltration. Brush pile leaves no adhesive residue on window frame aluminium or uPVC profiles when removed.

What bend radius limits must be respected when routing the flat hose?

The flat hose assembly contains two copper refrigerant tubes whose minimum bend radius is constrained by the wall thickness and annealing state of the copper. Midea specifies a minimum bend radius of approximately 150 mm for the PortaSplit flat hose — meaning the hose cannot be folded or creased sharply, but it can follow gentle curves from window to indoor unit position. Any bend tighter than 150 mm risks kinking the suction gas line, which reduces refrigerant flow cross-section and increases pressure drop across the suction side of the circuit.

In practice, the 150 mm minimum bend radius means the hose makes a single gentle curve from the window gap position (typically at wall height, 0.8–1.2 m above floor on a window sill) downward and then horizontally toward the indoor unit. A 90° direction change requires a bend arc at least 150 mm in radius — achievable in any room with a standard 2.4 m ceiling height. The maximum recommended hose length varies by model but is typically 3.0–5.0 m, beyond which refrigerant pressure drop and electrical cable voltage drop begin to reduce system efficiency.

The edge case: routing over door frames creates a double-bend that exceeds safe radius limits

A frequently attempted installation route is to pass the flat hose over or around a door frame to reach a window in an adjacent room. This introduces two 90° bends in close succession — one over the top of the door frame and one back to horizontal — with a combined path length that often forces each bend radius below the 150 mm minimum. The resulting kink in the suction gas line reduces effective cooling capacity and may eventually cause refrigerant line fatigue cracking at the kink point. Where cross-room routing is necessary, a 5 m extended hose set running under the door gap or along skirting board at a single gentle curve is the correct solution.

How does the flat hose compare thermally to a round monoblock exhaust hose?

A conventional monoblock exhaust hose carries hot condenser air at 55–65°C and transfers heat through its walls to any surface it contacts — including the indoor room, which it partially re-heats in the run between unit and window. The PortaSplit flat hose carries refrigerant: the suction line at approximately −5°C to +5°C (cold enough to condense moisture if uninsulated) and the liquid line at approximately 30–40°C. Both lines are thermally insulated within the flat bundle, so the outer surface of the hose is close to ambient room temperature rather than radiating 65°C exhaust heat into the space.

This thermal difference is non-trivial. A 1.5 m uninsulated 150 mm round exhaust hose at 60°C external surface temperature in a 22°C room radiates approximately 80–100 W of heat directly back into the cooled space — cooling that the compressor then has to re-remove. The PortaSplit flat hose at ambient surface temperature adds effectively zero radiant heat load to the room across the same run length, contributing directly to the efficiency advantage already created by the absence of negative pressure.

The flat hose routing through my window is genuinely invisible from outside — I had a visitor comment that they could not see how I had air conditioning at all. The window looks essentially closed. Tried a monoblock before and the big grey tube hanging out the window was the first thing everyone noticed.

Key takeaways on the Midea PortaSplit flat hose thickness and routing

The Midea PortaSplit flat hose thickness of 27 mm is not a marketing specification — it is the engineering detail that makes the entire rent-friendly, minimal-opening installation concept work. At 27 mm, the hose fits through a window gap narrower than a thumb width, requires no foam panel, adds zero radiant heat load to the room, and takes under two minutes to install or remove. The 150 mm minimum bend radius governs routing choices and rules out sharp direction changes, but any route that stays within this constraint delivers full refrigerant flow and rated system efficiency.

PortaSplit-class units with this flat hose architecture are among the most popular portable air conditioners in Europe, and stock is consistently depleted during heatwave events as renters and homeowners compete for the same units. Set your alert now to avoid the wait that follows every summer stock-out.