GB/T 27941-2026Requirements for the design and installation of multi-split air conditioning (heat pump) systems (English PDF)

5.1 General Requirements

5.1.1 The use of the rooms in the building, their usage requirements, cooling (heating) load characteristics, climate conditions, and energy availability should be considered, in conjunction with relevant national regulations. Safety, environmental protection, energy conservation, and hygiene regulations determine the following types of multi-split air conditioning (heat pump) units.

a) If the system is only operated in summer, a single-cooling system is recommended;

b) For systems that require operation in both winter and summer, a heat pump system is recommended;

c) When both cooling and heating are required in the same system, a heat recovery system is recommended;

d) In locations with peak-valley electricity pricing policies, energy storage (cold storage, heat storage) systems are recommended when the technical and economic analysis indicates their suitability.

e) In cold and frigid regions, when multi-split systems are used as the primary heating method, multi-split systems suitable for the corresponding environmental conditions should be adopted. Air conditioning (heat pump) unit.

5.1.2 The performance of the selected multi-split air conditioning (heat pump) unit shall comply with the provisions of GB 21454 and GB/T 18837.

5.1.3 The design of multi-split systems should be carried out according to the following steps.

a) Calculate the cooling (heating) load of the air-conditioned room and initially select the capacity of the indoor and outdoor units;

b) Based on the calculated load characteristics, the system should be rationally partitioned;

c) Based on project requirements and according to airflow organization and user requirements, select a suitable type of indoor unit;

d) Arrange indoor and outdoor units;

e) Design the connecting pipes for indoor and outdoor units;

f) Calculate the equivalent length of the connecting pipes for the multi-split system, and determine the equivalent length of the connecting pipes and the product specifications of the multi-split air conditioning (heat pump) unit. Verify the variable operating condition characteristics (curves or tables) provided by the manufacturer for the multi-split air conditioning system in terms of pipe length correction, elevation difference correction, and temperature correction. After adjusting the defrost (heating) and other data, check if the actual performance meets the requirements. If not, return to step a). Redesign;

5.2 Load Calculation and System Partitioning

5.2.1 The selection of indoor and outdoor design parameters and the load calculation of each room or area shall comply with the provisions of GB 50736.

5.2.2 Multi-split systems should be rationally zoned according to room orientation, function, usage time and frequency, and interior design conditions, and comply with... The following provisions apply.

a) In larger buildings or building areas, multiple multi-split air conditioning systems should be used;

b) For rooms or areas with many floor intervals, it is advisable to install separate multi-split air conditioning systems;

c) For buildings with multiple independent energy-consuming units or multiple business types belonging to different units, it is advisable to install separate multi-split air conditioning systems;

d) Based on the hourly load (Li) of each room, the system hourly load rate (La) and load synchronization rate (CURS) of each zone should be calculated to determine the system load factor (La) and load synchronization rate (CURS) of each zone. The system load synchronization rate (CURS,tau) for each partition system during the statistical period should be used. If CURS,tau < 0.7, the system partitions should be redefined.

5.2.3 When a room uses multiple multi-split air conditioning systems, a centralized controller should be used for overall management.

5.2.4 The design of multi-split systems shall comply with the following provisions.

a) The number of indoor units connected to the outdoor unit should be within the allowable range specified by the manufacturer;

b) The maximum length of the connecting pipe between indoor units after the first branch pipe of the system should not exceed the product's technical requirements;

c) The maximum pipe length and maximum height difference between indoor and outdoor units, as well as between indoor units, should not exceed the product's technical requirements;

d) Calculate the mass of refrigerant that needs to be added after the installation of the multi-split system, and the amount of additional refrigerant to be added compared with the amount of refrigerant pre-charged in the outdoor unit. The sum should not exceed the upper limit of refrigerant charge specified in the product's technical requirements.

5.3 Determination of the type and capacity of indoor and outdoor units

5.3.1 Indoor units can be classified into convection type indoor units, radiant type indoor units, and convection-radiant type indoor units according to their heat exchange method.

5.3.2 In scenarios where comprehensive protection of the indoor environment is not required, it is advisable to use indoor units designed for localized environmental protection (including radiant and convection-radiant types). (Type of indoor unit), and meet the following requirements in application design.

a) Use indoor units designed for localized environmental protection. The horizontal relative position of the indoor unit's air supply (radiant surface) to the protected area should be smaller than that of the room. The indoor unit capacity should be determined based on 50% of the length and the size of the protected area.

b) When using radiant indoor units for continuous heating, calculations have verified that the indoor unit temperature can be adjusted according to the required operating temperature. Calculate the room load based on temperature and determine the capacity of the indoor unit; when using radiant heating terminals laid on the floor, ensure they meet operational requirements. The indoor temperature load corresponding to the temperature requirement is calculated, or the capacity of the hot water module is determined by reducing the indoor design temperature by 2°C.

c) When using convection-radiation type indoor unit units, the capacity of the indoor unit should be determined according to the peak load of intermittent operation. The adjustable capacity of the indoor unit... The lower limit of the quantity should not be higher than the load calculated based on the indoor temperature corresponding to the operating temperature during the steady-state stage.

5.3.3 Determine the capacity of the outdoor unit based on the calculated cooling (heating) load of each area (room) under the same multi-split system.

5.3.4 When the design operating conditions of the multi-split system differ from the nominal operating conditions of the multi-split air conditioning (heat pump) unit, the actual cooling capacity of the multi-split system... The heat capacity should be adjusted based on factors such as design conditions, temperature, configuration ratio, pipe length, installation height difference between indoor and outdoor units, and defrosting, to determine the required heat capacity. The nominal cooling capacity and nominal heating capacity of the outdoor unit to be selected must be determined.

5.4 System Engineering Energy Efficiency Requirements For actual projects employing air-cooled and low-ambient-temperature air-source multi-split air conditioning (heat pump) units, it is advisable to consider the specific engineering conditions and refer to the appendix. Record A provides the method to calculate the energy efficiency parameters EAPF*, ESEER*, or EHSPF* for multi-split air conditioning systems, in order to compare them with other air conditioning solutions. A comparison and selection process was conducted.

5.5 Layout of Indoor and Outdoor Units

5.5.1 The layout of indoor units should meet the room's airflow organization requirements; for rooms requiring heating in winter, if the ceiling is high and a top-supply and top-return air supply system is used... When determining the airflow organization method, it is advisable to use airflow organization analysis to determine its installation height.

5.5.2 Avoid installing the indoor unit outdoors, in environments susceptible to oil fume pollution, acid or alkaline conditions, or strong electromagnetic interference. If this cannot be avoided, [the following should be done]. Special measures should be taken.

5.5.3 The layout of outdoor units shall follow the following principles.

a) It should be installed in a well-ventilated location, taking into account the impact of monsoons and outdoor wind fields on the exhaust of the outdoor unit;

b) It should be placed in a cool, shaded area and should not be placed in dusty, heavily polluted places or places where corrosive gases are emitted;

c) It should be installed away from electromagnetic radiation sources, and the distance between it and the radiation source should not be less than 1m;

d) The unit's exhaust ventilation should not affect the ventilation of neighboring households, and the operating noise should not affect neighboring households;

e) The unit's layout should minimize the total length of connecting pipes;

f) Sufficient installation and maintenance space or passageways should be provided between units and between units and surrounding obstacles, ensuring easy access for personnel. Meets the technical requirements of the product.

5.5.4 When the outdoor unit is installed on an installation platform on the building facade, the installation platform shall comply with the following requirements.

a) There should be no protruding walls or other obstacles between the installation platform and the balcony, window opening, or access door;

b) The angle between the facade where the installation platform is located and the facade where the balcony, window opening, or access door is located should not exceed 180°;

c) The height of the installation platform should not be higher than the balcony, window opening, or access door;

d) The installation platform should not be located in an enclosed space, and at least one facade of the upper space of the platform should be open to the outside;

5.6 Refrigerant Connection Pipe Design

5.6.1 The diameter of the connecting pipes and pipe fittings for multi-split air conditioning systems should be selected in accordance with the manufacturer's technical requirements.

5.6.2 Copper or stainless steel pipes should be used for connecting pipes in multi-split air conditioning systems. The material and specifications of copper pipes should conform to GB/T 1527 and GB/T 17791. According to regulations, the material and specifications of stainless steel pipes should conform to GB/T 12771.The nominal minimum wall thickness of connecting pipes should conform to Table 4. Regulation.

5.6.3 When determining the diameter of the connecting pipes between the indoor and outdoor units of a multi-split air conditioning system, the following regulations shall be met.

a) Between the outdoor unit and the branch pipe (or manifold). The refrigerant piping interface size should be the same as that of the outdoor unit, if specified by the product manufacturer. If different pipe diameters are to be used, connect the corresponding adapter according to the specifications, and then connect the connecting pipe with the specified pipe diameter;

b) Between the branch pipe (or manifold) and the indoor unit. The pipe interface size should be the same as that of the indoor unit, unless otherwise specified by the product manufacturer. For different pipe diameters, connect the corresponding adapter according to the specifications, and then connect the connecting pipe of the specified diameter;

c) Between branch pipes. depends on the total capacity of all indoor units connected to its downstream end;

d) When it is necessary to change the diameter of the connecting pipe, follow the product manufacturer's product technical documents.

5.6.4 When determining the length and height difference of the connecting pipes between indoor and outdoor units of a multi-split air conditioning system, and the height difference between indoor units, the following conditions must be met. Regulation.

a) Calculated based on the product technical documents, the maximum permissible equivalent length of the connecting pipe between the indoor and outdoor units meets the requirements after installation. The cooling capacity attenuation rate c of a multi-split system operating at full load under nominal cooling conditions should not exceed 20%, calculated according to formula (9). The COPcs of the multi-split system should not be lower than 2.80, calculated according to formula (10);

b) When the product technical documents cannot meet the accounting requirements, the maximum permissible equivalent length of the connecting pipe in the multi-split system, le,max, should not exceed [a certain value]. The maximum allowable length of the connecting pipe, lmax, should be calculated according to formula (11). The equivalent length corresponding to the local resistance component of the connecting pipe is determined by... The product manufacturer provides the data or calculates the values according to the recommendations in Table 5;

c) The maximum permissible height difference between indoor and outdoor units, and between indoor units, should not exceed the product's technical specifications. Require.

5.6.5 Manifolds should not be used for vertical branching. When there are extra branches in a manifold, the pipe ends should be flattened and welded to seal them.

5.6.6 The number of bends in the piping should be reduced. For multi-split systems with multiple branches, the branch point of the main pipe should be connected to the furthest indoor unit of each branch. The distance between groups should be equal.

5.6.7 When the refrigerant connection pipe passes through a beam, there should be no right-angle bends, liquid pockets, or air pockets. The method shown in Figure 1 should be used.

5.7 Thermal Insulation

5.7.1 The insulation design of all equipment, piping and accessories, and valves in a multi-split air conditioning system shall comply with GB/T 8175 and GB/T 4272. Regulation.

5.7.2 The insulation material for the connecting pipes, condensate pipes, and connecting ducts of the indoor units of the multi-split system should be non-combustible or flame-retardant foam. Insulating products made of rubber, plastic, polyethylene, or equivalent materials shall conform to the specifications of GB/T 8175, and their thermal conductivity (lambda) at 20°C shall not exceed [value missing]. Greater than

0.040 W/(m·K), and the moisture resistance factor should not be less than 5000.

5.7.3 The thickness of the insulation material used for the refrigerant connection pipe should be determined based on the outer diameter of the connection pipe and the thermal conductivity of the insulation material, and should meet the requirements. It conforms to the provisions of GB/T 8175 and meets the following requirements.

a) When there are no specific design requirements, the thickness of the insulation material can be selected according to Table 6;

b) When the thermal conductivity of the insulation material is other than a certain value, it can be corrected according to the product manufacturer's technical documentation requirements;

c) In humid areas, the thickness of the insulation material should be increased after calculation; in dry areas, the thickness of the insulation material should be increased after calculation. The reduction should be calculated in accordance with the provisions of GB/T 8175.

d) Insulation materials shall meet fire protection requirements.

5.8 Air Conditioning Condensate Pipe Design

5.8.1 The condensate drain pipes of the indoor unit should be laid out reasonably. The layout should follow the principle of "discharge as close as possible," draining the condensate to the bathroom, In kitchens and other areas with floor drains, condensate should either drain directly outdoors or be connected to a separate condensate riser. Minimize the number of indoor areas connected by the same condensate pipe. The number of generating units should be determined, and the condensate should flow from top to bottom into the centralized drainage pipe during the confluence process.

5.8.2 The pipe material for condensate pipes should preferably be rigid plastic pipe or hot-dip galvanized steel pipe.

5.8.3 Condensate pipes should be installed independently, separately from other building water pipes, and their length should be minimized. Horizontal condensate pipes should run along the water flow path. The slope should be set in the direction of flow, and the slope should not be less than 8 per mille. The selection of pipe diameter for rigid polyvinyl chloride (U-PVC) manifolds can be found in Table 7.

5.8.4 A downward-facing vent should be installed at the highest point of the condensate drain riser, and it should not be located at the condensate drain riser of an indoor unit equipped with a lift pump. Location near the water riser pipe.

5.8.5 Condensate drain pipes with different drainage pressures should not share the same horizontal drain main. If they must be shared, the horizontal drain main should be appropriately enlarged. The diameter of the water main pipe is adjusted to ensure that the flow is not completely full.

5.9 Fresh Air System Design The design of the fresh air system for multi-split air conditioning systems should comply with the provisions of GB 50736 and JGJ174.

5.10 Electrical and Control System Design

5.10.1 The electrical system of the multi-split air conditioning system shall be designed in accordance with the technical documents provided by the product manufacturer and comply with GB 51348. Regulation.

5.10.2 The power wiring specifications and circuit breakers for multi-split systems should be configured according to the maximum operating current of the multi-split air conditioning (heat pump) unit; each Each outdoor unit should be equipped with a separate air switch, and should comply with the requirements of GB 51348.

5.10.3 All indoor units of the same multi-split air conditioning system shall be powered by the same power distribution circuit.

5.10.4 The control system of the multi-split air conditioning system shall be designed in accordance with the technical documents provided by the product manufacturer and shall comply with JGJ174. Regulation.

5.11 Noise Reduction and Vibration Isolation The noise reduction and vibration isolation design of multi-split air conditioning systems should comply with the provisions of JGJ174.

6.1 General Provisions

6.1.1 The main equipment, materials, finished products, semi-finished products, and instruments of the multi-split air conditioning system shall be inspected upon unpacking, and the contents shall be checked in accordance with Table C.1 of Appendix C. Line record.

6.1.2 Multi-split air conditioning units should have a factory certificate of conformity and instruction manual, as well as other technical documents, including indoor units, outdoor units, connecting pipes, and fittings. The model, specifications, performance, and technical parameters of the equipment shall comply with GB/T 18837, GB 21454, and the product manufacturer's specifications; the outer surface of the equipment shall be free of... Damage should be present, seals should be in good condition, and all accompanying documents and accessories should be complete.

6.1.3 The engineering installation of multi-unit generators shall be carried out in accordance with the engineering design and product technical documents, and shall be coordinated with the building, structure, electrical, water supply and drainage, and equipment systems. The layout of the decoration and other related disciplines should be coordinated and reasonable, and should meet the safety requirements specified in GB/T 9237.

6.1.4 The installation and commissioning of multi-split air conditioning systems should be carried out in the following order.

a) Confirmation of construction drawings before construction;

b) Construction of pre-embedded pipelines during the construction phase;

c) Installation of indoor and outdoor units, and construction of refrigerant connection pipes;

d) Condensate pipe installation, air duct installation, and electrical engineering construction;

e) System purging, airtightness testing, insulation engineering, vacuum drying, refrigerant top-up and charging, condensate pipe filling and drainage. test;

f) Installation inspection, trial operation, acceptance, and delivery of equipment before power supply and operation.

6.1.5 For multi-split systems using flammable refrigerants, the installation shall meet the requirements of GB/T 9237.

6.2 Installation of Indoor Units

6.2.1 When moving indoor units, protective measures should be taken to prevent damage to the units.

6.2.2 When installing the indoor unit, a suitable location should be selected, and the indoor unit should be installed horizontally to ensure sufficient space for air supply and maintenance, and to guarantee... Overall aesthetics.

6.2.3 The lower end of the hoisting rod of the indoor unit must be fixed by double nuts tightening together, and the hoisting frame should be equipped with shock absorption measures.

6.2.4 Indoor units should be fixed independently and should not share supports or hangers with other equipment or pipelines or be suspended on hangers of other disciplines.

6.2.5 Four lifting rods should be used during hoisting. The lifting rods should be threaded rods with a diameter of not less than M

8.When the length of the lifting rod exceeds 1.5m, Take appropriate measures to prevent shaking during operation.

6.2.6 If the indoor unit is installed inside an enclosed ceiling space, an access panel should be provided for maintenance. The size of the access panel should not be smaller than 450mm×450mm.

6.2.7 After the indoor unit is installed, protective measures should be taken to prevent damage to the exterior and dust from entering the interior of the indoor unit.

6.2.8 For multi-split air conditioning systems using flammable refrigerants, refrigerant shut-off devices and refrigerant concentration detectors should be added to the inlet and outlet pipes of the indoor units. Alarm device, and conforms to the provisions of GB/T 9237.

6.3 Installation of outdoor unit

6.3.1 When hoisting the outdoor unit, no packaging should be removed. Two ropes should be used to hoist the unit while it is still packaged in all four directions, keeping the machine secure. Lift in a balanced, safe, and stable manner. The angle of the ropes should be less than 40° when lifting and moving; when handling without packaging, use padding or packaging materials. Protect.

6.3.2 When hoisting the outdoor unit, care should be taken to keep it vertical; during handling, its tilt angle should not exceed 45°, and attention should be paid to safety during handling and hoisting. Safety.

6.3.3 When the outdoor unit is installed under the eaves or where there are horizontal obstacles above the unit, the installation location should be selected in a well-ventilated area. Localities should also meet the following requirements.

a) Outdoor unit installed under the eaves. When D1 >= 3000mm, the installation location meets the requirements of the product manufacturer's technical documents; when 1500mm

b) When the outdoor unit is installed in a location with horizontal obstructions above it; when D1 >= 3000mm, the installation location must comply with the product manufacturer's technical specifications. Technical documents require that when D1<=3000mm, a wind cap, air duct, or airflow guide grille should be installed, see Figure 3.

a) When the generator unit is installed under the eaves;

b) When there are horizontal obstacles above the generator unit.

6.3.4 The air duct of the outdoor unit should have only one bend, and the air ducts of multiple outdoor units should be set up independently for each unit. A single bend should not be used. Centralized exhaust ventilation system.

6.3.5 The exhaust direction of a side-exhaust outdoor unit should preferably be consistent with the prevailing wind direction during the local air conditioning season; if it is opposite to the prevailing wind direction... When necessary, an outlet air guide device should be installed.

6.3.6 When installing outdoor units in areas with monsoons and snow cover, snow covers should be installed on the exhaust and intake vents of the outdoor units, and Outdoor units should be installed on a base or foundation with a height H of not less than 300mm. When considering snow depth, the height H of the base or foundation should be appropriate. Increase the height. See Figure 4 for the outdoor unit's snow protection device.

6.3.7 The outdoor unit shall be installed on a level and load-bearing foundation. The foundation height shall be greater than 100mm, and its length and width shall be determined according to the indoor... The model and number of outdoor units must be determined; the platform's load-bearing capacity should not be less than four times the sum of the outdoor unit's self-weight and the installer's weight, and should not be less than... At 400kg.

6.3.8 The outdoor unit and the foundation should have tight contact, and the connection between the outdoor unit and the foundation should be made in accordance with the requirements of the product manufacturer's technical documents. Vibration damping components should be installed between the outdoor unit and the foundation; when there are no specific requirements, 5mm-10mm thick rubber sheets can be used as vibration damping components between the outdoor unit and the foundation. Alternatively, corrugated rubber vibration damping pads should be used, and they should be installed along the length of the outdoor unit, not just at fixed points.

6.3.9 The outdoor unit shall be fixed to the foundation using anchor bolts. The bolt type shall meet the requirements of the product manufacturer's technical documents. They worked closely together during the foundation construction phase by the civil engineering professionals.

6.3.10 When using concrete foundations, the concrete strength grade should not be less than C

6.4 Processing, welding and installation of refrigerant connection pipes

6.4.1 The material, specifications, model, and welding materials of the connecting pipes and fittings of the multi-split air conditioning system shall be selected according to the requirements of the design documents. (Refrigeration) The connection method for connecting pipes should be selected based on the type of refrigerant, the fire safety conditions of the construction and maintenance environment, and its safety requirements should be met. It complies with GB/T 9237.

6.4.2 The inner and outer surfaces of the refrigerant connecting pipe should be smooth and clean, free from defects such as delamination, pinholes, and green rust, and should not have defects along the length of the pipe. The stretch marks.

6.4.3 Cleaned and qualified pipelines should be properly moisture-proofed. Both ends of the pipelines should be sealed or nitrogen-filled for protection, and they should be stored in a dry, well-ventilated place. A place to shelter from the wind and rain.

6.4.4 The processing of refrigerant connection pipes shall comply with the following provisions.

a) Use a special cutter to cut copper pipes. After cutting, use a deburring tool to remove excess burrs from the ends of the copper pipes, and then smooth the ends with a file. Tilting downwards removes chips adhering to the inner wall of the copper tube; b)...