Prevents acoustic amplification caused by nearby reflective surfaces<\/li>\n<\/ul>\nTypical minimum clearances:<\/strong><\/p>\n<\/div>\n\n
\n\n\n| Side<\/th>\n | Minimum Distance<\/th>\n | Recommended Distance<\/th>\n<\/tr>\n<\/thead>\n |
\n\n| Intake (front\/sides)<\/td>\n | 300 mm<\/td>\n | 600\u20131,000 mm<\/td>\n<\/tr>\n |
\n| Rear (wall side)<\/td>\n | 200\u2013300 mm<\/td>\n | 800\u20131,000 mm<\/td>\n<\/tr>\n |
\n| Discharge (front outlet)<\/td>\n | 1,000 mm<\/td>\n | 2,000\u20133,000 mm<\/td>\n<\/tr>\n |
\n| Top clearance<\/td>\n | 1,000 mm<\/td>\n | 1,500 mm<\/td>\n<\/tr>\n |
\n| Property boundary<\/td>\n | 2,000 mm<\/td>\n | 3,000\u20135,000 mm<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\nAlways confirm exact clearance requirements in the manufacturer’s installation manual. iDM TERRA AL and iPump A series units carry specific minimum clearances that supersede general guidelines.<\/em><\/p>\nPractical application:<\/strong> A unit installed 200 mm from a boundary wall with restricted front clearance will recirculate exhaust air. Research on heat pump outdoor unit arrays shows that increasing inter-unit spacing from 1.0 m to 1.5 m improved system COP by 11.5%. The same airflow physics apply to a single residential unit placed too close to a wall or fence.<\/p>\nFoundation and Mounting System<\/h3>\nDefinition:<\/strong> The foundation is the load-bearing structure on which the outdoor unit rests. The mounting system connects the unit to the foundation and provides vibration isolation.<\/p>\nPurpose:<\/strong> The foundation distributes the static weight of the unit \u2014 typically 60\u2013180 kg for residential units \u2014 across a stable ground area. It maintains level positioning over multiple freeze-thaw cycles and prevents frost heave from displacing the unit.<\/p>\nBenefits:<\/strong><\/p>\n\n- Prevents structural tilt that causes refrigerant oil distribution problems in the compressor<\/li>\n
- Isolates compressor vibration from the building structure to reduce structure-borne noise<\/li>\n
- Elevates the unit above snow accumulation and meltwater pooling<\/li>\n
- Provides a defined maintenance platform for service engineers<\/li>\n<\/ul>\n
Foundation types:<\/strong><\/p>\n\n- Concrete pad<\/strong> \u2014 poured in-situ or prefabricated; minimum 100 mm thick; includes drainage clearance beneath the unit<\/li>\n
- Prefabricated heat pump stand<\/strong> \u2014 manufacturer-specific; anti-vibration pads integrated; no concrete works required; recommended for retrofit installations<\/li>\n
- Adjustable wall bracket<\/strong> \u2014 attaches unit to the building facade; keeps unit off the ground entirely; can transmit low-frequency hum to the structure if anti-vibration isolation is insufficient<\/li>\n
- Roof mounting frame<\/strong> \u2014 used for flat-roof installations; requires structural load assessment; provides natural wind exposure without ground obstruction<\/li>\n<\/ul>\n
Alpine and cold-climate requirement:<\/strong> In regions with significant snowfall \u2014 including Tyrol, Vorarlberg, Bavaria, and the Swiss Alps \u2014 the unit must be elevated above the expected maximum snow depth. The standard guidance is a minimum of 300 mm above the anticipated snow line. In areas with recorded depths above 500 mm, a wall bracket or raised concrete plinth is the correct solution.<\/p>\nPractical application:<\/strong> iDM Energiesysteme GmbH supplies a purpose-built prefabricated foundation system aligned to the dimensional footprint of TERRA AL and iPump A outdoor units. Anti-vibration pads are included. No site-mixed concrete is required. The system reduces installation time and ensures correct elevation is maintained from the first day of operation.<\/p>\nOrientation and Aspect<\/h3>\nDefinition:<\/strong> Orientation refers to the compass direction the discharge face of the outdoor unit faces and the aspect of the site where the unit is positioned.<\/p>\nPurpose:<\/strong> Correct orientation prevents warm exhaust air from re-entering intake openings, reduces acoustic impact on living spaces and neighbouring properties, and manages solar and wind exposure at the evaporator coil.<\/p>\nBenefits:<\/strong><\/p>\n\n- Reduces frequency and duration of defrost cycles in winter<\/li>\n
- Lowers perceived sound levels at bedroom windows<\/li>\n
- Avoids direct solar heating of intake air, which reduces cooling-mode efficiency<\/li>\n
- Minimises wind-driven snow ingestion into the intake coil<\/li>\n<\/ul>\n
Orientation principles:<\/strong><\/p>\n\n- Discharge direction:<\/strong> Point discharge away from windows, doors, and adjacent structures. Discharge toward open garden space or driveway areas.<\/li>\n
- Intake direction:<\/strong> Position intake away from prevailing wind in exposed locations. Wind strips heat from the coil and can reverse fan blade rotation at startup.<\/li>\n
- North and east aspects:<\/strong> Positioning the outdoor unit on the north or east face of the building limits exposure to direct summer sun. Shading in summer does not reduce winter heating performance.<\/li>\n
- Corner and niche avoidance:<\/strong> Never position the unit in building corners, under low eaves, or in enclosed alcoves. These locations amplify sound by 3\u20136 dB(A) through reflective surfaces and trap exhaust air.<\/li>\n<\/ul>\n
Practical application:<\/strong> In a typical Austrian or South Tyrolean single-family home, the north-facing garden side is usually the correct placement zone. It separates the unit from living areas, provides discharge clearance, and avoids street-facing noise impact. This placement also coincides with shorter refrigerant line routing when the indoor unit is located in a utility room adjacent to the north wall.<\/p>\nDistance to Indoor Unit<\/h3>\nDefinition:<\/strong> The refrigerant line set distance is the physical length of insulated tubing running between the outdoor and indoor units.<\/p>\nPurpose:<\/strong> Shorter line sets reduce refrigerant pressure drop, minimise thermal losses, and simplify installation. They directly affect the efficiency at which thermal energy is delivered to the hydraulic heating system.<\/p>\nBenefits:<\/strong><\/p>\n\n- Reduces refrigerant charge volume, lowering F-gas regulatory complexity<\/li>\n
- Lowers heat loss in the suction line<\/li>\n
- Reduces installation material cost and labour time<\/li>\n
- Maintains higher refrigerant pressure at the indoor expansion valve, improving COP<\/li>\n<\/ul>\n
Line set guidelines:<\/strong><\/p>\n\n- Position the outdoor unit as close to the building penetration as clearance requirements allow<\/li>\n
- Keep the line set horizontal or with a gentle upward slope from outdoor to indoor unit<\/li>\n
- Maximum line set lengths are specified by the manufacturer \u2014 for most residential iDM units, this falls in the range of 15\u201330 m equivalent pipe length<\/li>\n
- All line sets must be insulated with UV-rated foam insulation and protected where exposed to mechanical damage or UV degradation<\/li>\n<\/ul>\n
Practical application:<\/strong> An installer who places the outdoor unit in a distant garden corner for visual reasons may create a line set of 20 m where 5 m would have been sufficient. The additional length creates measurable pressure drop and ongoing thermal loss. Correct placement prioritises performance proximity first, then aesthetic screening second.<\/p>\nAcoustic Management<\/h3>\nDefinition:<\/strong> Acoustic management in outdoor unit placement is the set of positioning and screening decisions that control sound emission levels reaching neighbouring receivers.<\/p>\nPurpose:<\/strong> Heat pump outdoor units generate broadband noise from the fan motor, compressor, and refrigerant flow. This noise must remain below regulatory limits at the property boundary and at the facade of any adjacent building with sensitive uses.<\/p>\nBenefits:<\/strong><\/p>\n\n- Ensures compliance with \u00d6NORM S 5021, TA L\u00e4rm, and LSV without costly post-installation remediation<\/li>\n
- Maintains good relationships with neighbours \u2014 a common source of heat pump disputes in dense residential areas<\/li>\n
- Permits night operation in sound-reduced mode without exceeding nocturnal limits<\/li>\n
- Protects subsidy eligibility and building permits<\/li>\n<\/ul>\n
Acoustic placement principles:<\/strong><\/p>\n\n- Distance attenuation:<\/strong> Sound pressure level falls with distance. A 3 m setback from the property boundary is a widely applied guideline across DACH markets.<\/li>\n
- Reflective surfaces:<\/strong> Every hard reflective surface within 2 m of the unit increases perceived sound levels by 3\u20136 dB(A). Avoid positioning against masonry corners.<\/li>\n
- Vegetation screening:<\/strong> Dense hedging at an appropriate distance provides both visual and acoustic screening without restricting airflow. Minimum planting distance from the intake face: 2 m.<\/li>\n
- Acoustic barriers:<\/strong> Proprietary sound-reducing hoods reduce airborne sound levels by 9\u201315 dB(A) but must not obstruct intake or discharge air paths.<\/li>\n
- Bedroom and living room windows:<\/strong> The discharge face should never point directly toward bedroom windows \u2014 neither in the owner’s home nor in neighbouring properties.<\/li>\n<\/ul>\n
Regulatory reference:<\/strong> In Austria, a permit may be required for units with a sound power level above 45 dB(A) outdoors, unless an acoustic assessment confirms compliance with immission limits at the property boundary. Requirements vary by Bundesland. iDM Energiesysteme provides a dedicated sound calculation tool that models immission levels based on unit sound power data per EN 12102, placement geometry, and site conditions.<\/p>\nDrainage and Condensate Management<\/h3>\nDefinition:<\/strong> Condensate management encompasses the positioning and foundation design decisions that allow defrost meltwater to drain away from the outdoor unit without accumulating, refreezing, or causing structural damage.<\/p>\nPurpose:<\/strong> During heating operation in cold conditions, moisture in outdoor air freezes onto the evaporator coil. The heat pump runs periodic defrost cycles to clear this ice. Large volumes of water are released quickly. This water must drain completely before the next frost cycle begins.<\/p>\nBenefits:<\/strong><\/p>\n\n- Prevents ice formation beneath and around the unit that can block airflow<\/li>\n
- Protects the evaporator coil from ice bridging damage \u2014 a failure mode typically excluded from warranty<\/li>\n
- Reduces defrost cycle frequency by maintaining a clear coil base<\/li>\n
- Prevents meltwater from creating slip hazards on adjacent paths and driveways<\/li>\n<\/ul>\n
Drainage requirements:<\/strong><\/p>\n\n- The foundation surface must slope away from the unit base in all directions<\/li>\n
- The unit must be elevated above the surrounding ground to allow freeflow drainage<\/li>\n
- Do not install the unit in drainage sumps, depressions, or paved areas without a drain gulley<\/li>\n
- Keep the area beneath the unit clear of gravel, stones, or debris that can trap water and refreeze<\/li>\n<\/ul>\n
Eaves and roof drip lines:<\/strong> Avoid positioning the unit directly below roof eaves or gutterless overhangs. Concentrated roof runoff and falling snow deposit heavily on the coil. This increases defrost frequency, reduces efficiency, and can cause physical damage to the coil and casing. If eave-adjacent installation is unavoidable, fit a purpose-designed drip shield approved by the manufacturer.<\/p>\n<\/span>Types of Outdoor Unit Installation Scenarios<\/span><\/h2>\nGround-Level Installation on Concrete Foundation<\/h3>\nThe most common installation type. The outdoor unit sits on a concrete pad or prefabricated stand at grade level. The pad is elevated 100\u2013150 mm above the surrounding ground surface to provide drainage clearance and snow separation.<\/p>\n Best for:<\/strong> Properties with stable, well-drained ground, moderate snowfall, and adequate open space to achieve all clearances.<\/p>\nKey requirements:<\/strong> Frost-proof foundation depth (minimum 800 mm below grade in central Europe), anti-vibration pad between unit feet and pad surface, drainage gradient away from pad edges.<\/p>\nRaised Wall Bracket Installation<\/h3>\nThe outdoor unit is mounted on steel brackets fixed to the building facade, typically 300\u2013600 mm above finished ground level or above the maximum expected snow depth.<\/p>\n Best for:<\/strong> Properties with high snowfall exposure, limited ground space, or where ground-level frost heave is a known risk.<\/p>\nKey requirements:<\/strong> Structural assessment of the wall to confirm bracket load capacity, anti-vibration isolation between bracket and masonry, minimum clearance from the wall surface maintained by bracket offset.<\/p>\nFlat Roof Installation<\/h3>\nThe outdoor unit is installed on a purpose-built frame on a flat roof. Natural height provides excellent discharge clearance and removes the unit from the inhabited zone around the property.<\/p>\n Best for:<\/strong> Multi-family buildings, commercial applications, or single-family homes where ground space is critically limited.<\/p>\nKey requirements:<\/strong> Structural load verification by qualified engineer, waterproof frame base, dedicated service access route to roof, wind baffle design for exposed locations.<\/p>\nTandem and Cascade Installations<\/h3>\nTwo or more outdoor units installed in a coordinated array. Used for higher heating capacity requirements or cascade redundancy systems.<\/p>\n Best for:<\/strong> Larger residential buildings, commercial buildings, and iDM TERRA AL 60 Max commercial configurations.<\/p>\nKey requirements:<\/strong> Minimum 1.5 m lateral spacing between unit intakes to prevent airflow interference; shared foundation or aligned mounting frames; acoustic modelling for cumulative sound emission; coordinated discharge direction to prevent mutual exhaust recirculation.<\/p>\n<\/span>Benefits of Correct Outdoor Unit Placement<\/span><\/h2>\nCorrect placement directly determines operational performance across the full system life. The benefits are quantifiable:<\/p>\n Energy efficiency:<\/strong><\/p>\n |