Install a mobile air conditioner: steps & tips

Discover how to properly install your mobile air conditioner in 7 key steps. Window duct, sealing, condensate drainage and landlord constraints.

# Installing a Mobile Air Conditioner: Steps & Tips

Installing a mobile air conditioner represents one of the most accessible cooling solutions for renters and homeowners. Unlike fixed air conditioners, these devices require little structural work and comply with legal lease restrictions. However, poorly executed installation reduces energy efficiency by 20 to 30% and risks damaging your home. This guide provides you with best practices validated by French and European standards.

How to Position Your Mobile Air Conditioner Correctly?

The optimal positioning of a mobile air conditioner determines 40% of its energy efficiency. The unit must be placed in close proximity to an opening (window, French door or skylight) to expel hot air outside. Ideally, 30-50 cm from the ground, away from obstacles and direct heat sources.

Choosing the Right Opening

Standard windows: prioritize a rarely used window, facing north or east to avoid solar gain. South-facing windows capture 5 to 7 times more heat in summer.

French doors: ideal solution if you have a specific weatherstripping kit. The unit is installed perpendicular to the opening.

Skylights and roof windows: technically possible with adapted kits, but vertical evacuation of the hose reduces efficiency by 15%. Prefer a side window if you have the choice.

Distance and Clearance

Maintain at least 50 cm between the back of the unit and walls or furniture. This air circulation prevents compressor overheating and extends the lifespan by 3 to 5 years. Keep it away from curtains, blinds and textiles that obstruct circulation grilles.

What is the best method for fixing the duct?

The exhaust duct must be rigid or semi-rigid, never completely flexible. An excessively corrugated duct creates pockets of stagnant air that reduce thermal efficiency by 25%. Fixing is done at three points: appliance outlet, window passage and external outlet.

Fixing to the window frame

1. Install the sealing kit supplied with your air conditioner (adhesive foam joint or clip system).

2. Pass the duct through the semi-closed window opening.

3. Fix with high-performance adhesive tape (cloth tape type) every 20 cm.

4. Check the seal: no air should escape between the duct and the frame.

Skylights and roof windows

Use a specific Velux kit (available from manufacturers Tempéra, Trotec, Delonghi). These kits include a reinforced sealing joint and a mounting bracket that matches the Velux geometry. Installation takes 15 minutes without tools.

Wall passage

If the duct exits through an external wall, install a wall passage with non-return flap (approximately 25 €). This flap prevents hot air from returning in winter and insects from entering permanently. Seal with high-temperature silicone sealant.

Why is weatherstripping essential?

A faulty weatherstrip causes cold air leaks of 15 to 40%, canceling out 30% of your unit's cooling power. Weatherstripping creates an airtight barrier between the air-conditioned interior and the hot exterior, limiting parasitic air infiltration that forces the compressor to overwork.

Types of weatherstripping kits

Adhesive foam seal: economical solution (€5-8), effective for 1-2 seasons. Perfect for renters.

Clip and rail system: more durable (2-3 seasons), requires a bit more dexterity. Cost: €15-25.

Magnetic weatherstripping strips: recent innovation, reusable, ideal for metal windows. Price: €30-40.

Step-by-step application

1. Clean the window frame with a dry cloth.

2. Unroll the foam seal continuously, without overlap.

3. Press firmly for 5 seconds every 10 cm.

4. Let rest for 24 hours before closing the window.

5. Test the seal by passing your hand: no air draft should be noticeable.

Condensate Drainage Management

A mobile air conditioner generates 0.5 to 1.5 liters of water per hour depending on ambient humidity and device power. This water must be evacuated regularly to prevent overflows and water damage.

Recovery System

Removable tank: emptied manually 1 to 2 times per day. Suitable for small spaces (< 30 m²).

Continuous drainage: tube connected to a sink siphon or outdoor garden hose. Ideal for 8+ hours/day operation. Install a check valve (backflow preventer) to prevent water backflow.

Garden hose: free option if you have a balcony or terrace. Minimum slope: 1 cm per meter to prevent stagnation.

Condensate Maintenance

Clean the tank every 15 days with a mixture of water + white vinegar (1:1 ratio) to prevent mold and odors. Check monthly that the drainage tube is not blocked by debris.

Legal Constraints: Tenant Rights in France, Germany, and Switzerland

French law ([article L.145-8 of the Monetary and Financial Code](https://www.legifrance.gouv.fr)) allows tenants to install a mobile air conditioner without prior landlord authorization, provided the device is removable and causes no permanent damage. However, variations exist depending on the region.

France

• Installation authorized for mobile air conditioners without structural work.
• Tenant obligation: restore the premises to their original condition at the end of the lease (remove the duct, fill in fixing holes).
• Liability: damage resulting from improper installation (water leakage, electrical damage) is the tenant's responsibility.
• Recommended consultation: check your lease; some landlords prohibit mobile air conditioners or require enhanced water damage insurance.

Germany

German law (BGB § 554) is more restrictive: installing a mobile air conditioner may be considered a modification of the dwelling. The tenant must obtain written consent from the landlord. However, "non-invasive" devices (without drilling) are often tolerated. Consult your Mietvertrag (rental agreement).

Switzerland

In French-speaking and German-speaking Switzerland, the [Code of Obligations (CO, art. 257)](https://www.admin.ch/opc/fr/classified-compilation/19070042/index.html) allows tenants to make minor improvements without prior consent, provided they are reversible. A mobile air conditioner falls into this category. However, inform your landlord and document the installation with photos.

Common Mistakes to Avoid

Duct Too Long or Too Wavy

A duct longer than 2 meters with multiple bends reduces efficiency by 20%. Prioritize the most direct path to the outside.

Completely Closing the Window

Never completely close the window on the duct. Leave a gap of at least 2-3 cm to balance interior pressure. A hermetically sealed window creates a vacuum that forces the compressor to overwork.

Missing Check Valve

Without a check valve, hot air returns into the home in late afternoon or winter. Install it mandatory on the external outlet.

Forgetting to Clean Filters

A clogged filter reduces air flow by 40% in 3 weeks. Clean filters every 7 days in summer.

Placement Against a Wall or Furniture

Hot air expelled from the back of the unit must circulate freely. Placement against a wall creates a thermal loop that reduces efficiency by 30%.

Final Installation Checklist

• ☐ Air conditioning unit positioned 30-50 cm from the ground, away from obstacles.
• ☐ Rigid or semi-rigid duct, length < 2 m, without excessive bends.
• ☐ Sealing kit applied correctly, no air leaks detected.
• ☐ Check valve installed on the external outlet.
• ☐ Condensate evacuation system functional (pan or pipe).
• ☐ Power cable without knots, NF certified outlet.
• ☐ 30-minute operation test: verify indoor temperature and absence of abnormal noise.
• ☐ Installation documentation preserved (photos, serial number) for the landlord.

Conclusion

Installing a mobile air conditioner in 7 key steps (positioning, hose fixing, sealing, condensate drainage, check valve, filter cleaning, testing) guarantees optimal performance and extended lifespan. Respect your region's legal constraints and document each step to avoid disputes with your landlord. A properly installed air conditioner consumes 15% less electricity and provides stable thermal comfort throughout the summer.

Mots-clés : climatiseur mobile, installation, gaine fenêtre, locataire, condensats