Electric air conditioning systems designed for permanent installation shall comply with UL 1995 or UL 60335-2-40.
Gas piping serving heating appliances shall be permitted to serve cooling appliances where heating and cooling appliances are not capable of being operated simultaneously. [NFPA 54:10.2.1] (See Section 1308.4)
To protect against the effects of normal vibration in service, gas engines shall not be rigidly connected to the gas supply piping. [NFPA 54:10.2.2]
The installation of air-conditioning appliances shall comply with the following requirements:
- Listed air-conditioning appliances shall be installed with clearances in accordance with the terms of their listing and the manufacturer's installation instructions.
- Unlisted air-conditioning appliances shall be installed with clearances from combustible material of not less than 18 inches (457 mm) above the appliance and at the sides, front, rear and in accordance with the manufacturer's installation instructions. [NFPA 54:10.2.3(2)]
- Listed and unlisted air-conditioning appliances shall be permitted to be installed with reduced clearances to combustible material, provided the combustible material or appliance is protected as described in Table 303.10.1 and such reduction is allowed by the manufacturer's installation instructions. [NFPA 54:10.2.3(3)]
- Where the furnace plenum is adjacent to plaster on metal lath or noncombustible material attached to combustible material, the clearance shall be measured to the surface of the plaster or other noncombustible finish where the clearance specified is not more than 2 inches (51 mm). [NFPA 54:10.2.3(4)]
- Listed air-conditioning appliances shall have the clearance from supply ducts, within 3 feet (914 mm) of the furnace plenum, be not less than that specified from the furnace plenum. No clearance is necessary beyond this distance. [NFPA 54:10.2.3(5)]
Air-conditioning appliances shall be installed in accordance with the manufacturer's installation instructions. Unless the appliance is listed for installation on a combustible surface, such as a floor or roof, or unless the surface is protected in an approved manner, it shall be installed on a surface of noncombustible construction with noncombustible material and surface finish and with no combustible material against the underside thereof. [NFPA 54:10.2.4]
A furnace plenum supplied as a part of the air-conditioning appliance shall be installed in accordance with the manufacturer's installation instructions. Where a furnace plenum is not supplied with the appliance, fabrication and installation instructions provided by the manufacturer shall be followed. The method of connecting supply and return ducts shall facilitate circulation of air. Where the air conditioner is installed within a c1oset, the air circulated by the appliance shall be handled by ducts that are scaled to the casing of the appliance and that separate the circulating air from the combustion and ventilation air. [NFPA 54:10.2.5]
Means for interrupting the electrical supply to the air-conditioning appliance and to its associated cooling tower (where supplied and installed in a location remote from the air conditioner) shall be provided within sight of and not over 50 feet (15240 mm) from the air conditioner and cooling tower. [NFPA 54:10.2.7]