CHAPTER 3 GENERAL REQUIREMENTS 30.0 Scope General. 30. Applicability. This chapter covers general requirements for heating, ventilating, air-conditioning, refrigeration, miscellaneous heat-producing, and energy-utilizing equipment. Such equipment shall conform to the requirements of this code. Equipment shall not be installed or altered in violation of this code, nor shall the fuel input rate to equipment be increased in excess of the approved british thermal unit per hour (Btu/h) (kw) rating at the altitude where it is being used. Defective material or parts shall be replaced in such a manner as not to invalidate any an approval. 302.0 Approval. 302. How Obtained. Each appliance shall be approved by the Authority Having Jurisdiction for safe use or comply with applicable nationally recognized standards as evidenced by the listing and label of an approved agency. A list of accepted standards is included in Chapter 7. 302.2 Complying Design of Equipment. Installers shall furnish satisfactory evidence that the appliance is constructed in accordance with the requirements of this code. The permanently attached label of an approved agency shall be permitted to be accepted as such evidence. 302.3 Oil-Burning Appliances. The tank, piping, and valves for appliances burning oil shall be installed in accordance with the requirements of NFPA 3. 303.0 Installation. 303. Installation Practices. Mechanical systems shall be installed in a manner in accordance with this code, applicable standards, and the manufacturer s installation instructions. 303.2 Listed Appliances. Except as otherwise provided in the code, the installation of appliances regulated by this code shall be in accordance with the conditions of listing. The appliance installer shall leave the manufacturer s installation and operating instructions attached to the appliance. Clearances of listed appliances from combustible materials shall be as specified in the listing or on the rating plate. 303.3 Room Large in Comparison to Size of Equipment. Central-heating furnaces not listed for closet or alcove installation shall be installed in a room or space having a volume not less than times the total volume of the furnace; central-heating boilers not listed for closet or alcove installation shall be installed in a room or space having a volume times the volume of the boiler. Exception: The installation clearances for furnaces and boilers in rooms not large in comparison with the size of the equipment shall be as specified in the appliance listing regardless of whether the enclosure is of combustible or noncombustible materials and shall not be reduced by the protection methods described in Table 303.3(a) or any other method. Where the ceiling height of the room or space exceeds 8 feet (2438 mm), the volume shall be calculated on the basis of an 8 foot (2438 mm) height. 303.4 Unlisted Appliances. Unlisted appliances shall be installed with the standard clearances from combustible construction specified in Table 303.4. Unlisted appliances may shall have the standard clearances of Table 303.4 reduced by employing the forms of protection specified in Table 303.3(a). Forms of protection specified in Table 303.3(a) shall be permitted to be utilized to reduce clearances to combustible construction for all applicable appliances. 303.5 Anchorage of Appliances. Appliances designed to be fixed in position shall be securely fastened in place in accordance with the manufacturer s installation instructions. Supports for appliances shall be designed and constructed to sustain vertical and horizontal loads within the stress limitations specified in the building code. 303. Movement. Movement of appliances with casters shall be limited by a restraining device installed in accordance with the connector and appliance manufacturer s installation instructions. 303.7 Identification of Equipment. Where more than one heating, cooling, ventilating, or refrigerating system is installed on the roof of a building or within a building, it shall be permanently identified as to the area or space served by the equipment. 303.8 Liquefied Petroleum Gas Facilities. Containers, container valves regulating equipment, and appurtenances for the storage and supply of liquefied petroleum gas shall be installed in accordance with NFPA 58. 303.9 Equipment on Roofs. 303.9. Enclosures. Equipment on roof shall be designed or enclosed so as to withstand climatic conditions in the areas in which it is installed. Where enclosures are provided, each enclosure shall be of reasonable height, and shall have not less than a 30 inch (72 mm) clearance between the entire service access panel(s) of the equipment and the wall of the enclosure. 303.9.2 Roof Support. Roofs on which equipment is to be installed shall be capable of supporting the additional load or shall be reinforced to support the additional load. 303.9.32 Corrosion Resistance. Access locks, screws, and bolts shall be of corrosion-resistant material. 303.9.43 Roof Drainage. Equipment shall be installed on a well-drained surface of the roof. 303.9.54 Guards or Rails. Not less than feet (29 mm) between a part of the equipment and the edge of a roof or similar hazard, or rigidly fixed rail, guards, parapets, or other building structures not less than 42 inches (07 mm) in height shall be provided on the exposed side. UNIFORM MECHANICAL CODE 23
303.9.5 Electrical Power. Equipment requiring an external source of electrical power for its operation shall be provided with the following: () Readily accessible electrical disconnecting means within sight of the equipment. (2) A 0 VAC grounding-type receptacle outlet on the roof adjacent to the equipment. The receptacle outlet shall be on the supply side of the disconnect switch. 304.0 Service and Access to Equipment and Appliances. 304. General. Equipment and appliances shall be accessible for inspection, service, repair, and replacement without removing permanent construction. Clearance shall be maintained to: () Clean heating surfaces. (2) Replace filters, blowers, motors, burners, controls, and vent connections. (3) Lubricate moving parts. (4) Adjust and clean burners, pilots, and the proper functioning of explosion vents, where provided. [NFPA 54:9.2.] Unless otherwise specified, not less than 30 inches (72 mm) in depth, width, and height of working space shall be provided. Exception: Unit heaters and room heaters shall be permitted to be installed with an inches (457 mm) minimum depth working space. A platform shall not be required for unit heaters or room heaters. The operating instructions shall be attached to the appliance where they can be are capable of being read easily. 304. Access to Equipment and Appliances on Roofs. 304.. General. Appliances located on roofs or other elevated locations shall be accessible. [NFPA 54:9.4.3.] 304..2 Access from Inside. Buildings exceeding 5 feet (4572 mm) in height shall have an inside means of access to the roof, unless other means acceptable to the Authority Having Jurisdiction are used. [NFPA 54:9.4.3.2] 304..2. Door or Scuttle. The inside means of access shall be a permanent or foldaway inside stairway or ladder, terminating in an enclosure, scuttle, or trap door. Such scuttles or trap doors shall be not less than 22 inches x by 24 inches (50 mm x by 0 mm) in size, shall open easily and safely under all conditions, especially snow, and shall be constructed so as to permit access on the inside. 304..2.2 Permanent Ladders. Permanent ladders required by Section 304..2. shall be constructed in accordance with the following: () Have side railings which extend not less than 30 inches (72 mm) above the roof or parapet wall. (2) Landings shall not exceed feet (5 mm) apart measured from the finished grade. (3) Width shall be not less than 4 inches (35 mm) on center. (4) Rungs shall not exceed 4 inches (35 mm) on center. (5) Toe space shall not be not less than inches (52 mm). 304..2.3 Guards or Rails. Not less than feet (29 mm) of clearance shall be available between the access opening and the edge of the roof or similar hazard, or rigidly fixed rails or guards not less than 42 inches (07 mm) in height shall be provided on the exposed side. Where parapets or other building structures are utilized in lieu of guards or rails, they shall be not less than 42 inches (07 mm) in height. [NFPA 54:9.4.3.3] 304..32 Permanent Lighting. Permanent lighting shall be provided at the roof access. The switch for such lighting shall be located inside the building near the access means leading to the roof. [NFPA 54:9.4.3.4] 304..43 Standing Water. Where water stands on the roof at the equipment, in the passageways to the equipment, where the roof is of a design having a water seal, a platform, walkway, or both shall be provided above the waterline. Such platform(s) or walkway(s) shall be located adjacent to the equipment and control panels so that the equipment can be is capable of being safely serviced where water stands on the roof. 305.0 Automatic Control Devices. 305. General. Heating appliances shall be equipped with a listed device or devices that will shut off the fuel supply to the main burner or burners in the event of pilot or ignition failure. Liquefied petroleum gas-air-burning heating appliances shall be equipped with a listed automatic device or devices that will shut off the flow of gas to the pilot in the event of ignition failure. Exception: The listed shutoff devices shall not be required on range or cooking tops, log lighters, lights, or other open-burner manually operated appliances, or listed appliances not requiring such devices and specific industrial appliances as approved by the Authority Having Jurisdiction. Heating appliances whose manual fuel controls are not readily accessible from the main portion of the building being heated shall be equipped with remote controls. Forced-air and gravity-type warm-air furnaces shall be equipped with a listed air outlet temperature limit control that cannot be set for temperatures exceeding 250 F ( C). Such controls shall be located in the bonnet or plenum, within 2 feet (0 mm) of the discharge side of the heating element of gravity furnaces or in accordance with the conditions of listing. Electric duct heaters shall be equipped with an approved automatic reset air outlet temperature limit control that will limit 24 UNIFORM MECHANICAL CODE
the outlet air temperature to not exceed 200 F (93 C). The electric elements of the heater shall be equipped with fusible links or a manual reset temperature limit control that will prevent outlet air temperature in excess of 250 F ( C). 30.0 Standards. 30. General. Standards listed or referred to in this chapter or other chapters cover materials that will conform to the requirements of this code, where used in accordance with the limitations imposed in this or other chapters thereof and their listing. Where a standard covers materials of various grades, weights, quality, or configurations, there shall be permitted to be a portion of the listed standard that is applicable. Design and materials for special conditions or materials not provided for herein shall be permitted to be used by special permission of the Authority Having Jurisdiction after the Authority Having Jurisdiction has been satisfied as to their adequacy. A list of accepted mechanical material standards is included in Table 70.0. 307.0 Labeling. 307. Marking. Each length of pipe and each pipe fitting, material, and device used in a mechanical system shall have cast, stamped, or indelibly marked on it the manufacturer s mark or name, which shall readily identify the manufacturer to the end user of the product. Where required by the approved standard that applies, the product shall be marked with the weight and the quality of the product. Materials and devices used or entering into the construction of mechanical systems, or parts thereof, shall be marked and identified in a manner satisfactory to the Authority Having Jurisdiction. Such marking shall be done by the manufacturer. Field markings shall not be acceptable. 307.2 Fuel-Burning Appliances. Fuel-burning heating appliances shall bear a permanent and legible factory-applied nameplate on which shall appear: () The manufacturer s name. (2) The approved fuel input rating of the appliance, expressed in Btu/h (W). (3) The model and serial number. (4) Instructions for the lighting, operation, and shutdown of the appliance. (5) The type of fuel approved for use with the appliance. () The symbol of an approved agency certifying compliance of the equipment with recognized standards. (7) Required clearances from combustible surfaces on which or adjacent to which it is permitted to be mounted. 307.3 Electric Heating Appliances. Electric heating appliances shall bear a permanent and legible factory-applied nameplate on which shall appear: () The name or trademark of the manufacturer. (2) The catalog (model) number or equivalent. (3) The electrical rating in volts, amperes (or watts), and; for other than single phase, the number of phases. (4) The output rating in Btu/h or kw. (5) The electrical rating in volts, amperes, or watts of each field-replaceable electrical component. () The symbol of an approved agency certifying compliance of equipment with recognized standards. (7) Required clearances from combustible surfaces on which or adjacent to which it is permitted to be mounted. An appliance shall be accompanied by clear and complete installation instructions, including required clearances from combustibles other than mounting or adjacent surfaces, and temperature rating of field-installed wiring connections exceeding 40 F (0 C). 307.4 Heat Pump and Electric Cooling Appliances. Heat pumps and electric cooling appliances shall bear a permanent and legible factory-applied nameplate on which shall appear: () The name or trademark of the manufacturer. (2) The catalog model nomenclature. (3) The amount and type of refrigerant. (4) The factory test pressures or pressures applied. (5) The electrical rating in volts, amperes, and, for other than single phase, the number of phases. () The output rating in Btu/h or W. (7) The electrical rating in volts, amperes, or watts of each field replaceable electrical component. (8) The symbol of an approved agency certifying compliance of the equipment with recognized standards. (9) Required clearances from combustible surfaces on which or adjacent to which it is permitted to be mounted. An appliance shall be accompanied by clear and complete installation instructions, including required clearances from combustible other than mounting or adjacent surfaces, and temperature rating of field-installed wiring connections exceeding40 F (0 C). 308.0 Location. 308. Protection Against Damage. 308.. Igniting Hazard. Gas utilization appliances in garages and in adjacent spaces that open to the garage and are not part of the living space of a dwelling unit shall be installed so that burners and burnerignition devices are located not less than inches (457 mm) above the floor unless listed as flammable vapor ignition resistant. 308..2 Physical Damage. Appliances installed in garages, warehouses, or other areas subject to mechanical damage shall be guarded against such damage by being installed behind protective barriers or by being elevated or located out of the normal path of vehicles. 308..32 Access from the Outside Only. Where such appliances installed within a garage are enclosed in a separate, approved compartment having access only from outside of the garage, such appliances shall be permitted to be installed at floor level, provided the required combustion air is taken from and discharged to the exterior of the garage. 308..43 Cellulose Nitrate Plastic Storage. Heating equipment located in rooms where cellulose UNIFORM MECHANICAL CODE 25
nitrate plastic is stored or processed shall be in accordance with the Ffire Ccode. 308.2 Protection Against Flood Damage. For buildings located in flood hazard areas, heating, ventilating, air-conditioning, refrigeration, miscellaneous heat-producing, and energy-utilizing equipment and appliances shall be elevated at or above the elevation required by the building code for utilities and attendant equipment or the elevation of the lowest floor, whichever is higher. Exception: Equipment and appliances are permitted to be located below the elevation required by the building code for utilities and attendant equipment or the elevation of the lowest floor, whichever is higher, provided that they are designed and installed to prevent water from entering or accumulating within the components and to resist hydrostatic and hydrodynamic loads and stresses, including the effects of buoyancy, during the occurrence of flooding to such elevation in accordance with the flood-resistant construction requirements of the building code. 308.2. Walls Below Buildings in Flood Hazard Areas Subject to High Velocity Wave Action. In flood hazard areas subject to high velocity wave action, equipment and appliances, including piping, shall not be mounted on or penetrate walls intended to break away under flood loads. 308.2.2 Air Exhaust and Intake Openings. Outside air exhaust openings and air intake openings shall be located at or above the elevation required by the building code for utilities and attendant equipment or the elevation of the lowest floor, whichever is higher. 309.0 Improper Location. 309. General. Piping or equipment shall not be so located as to interfere with the normal use thereof or with the normal operation and use of windows, doors, or other required facilities. 30.0 Electrical Connections. 30. General. Equipment regulated by this code requiring electrical connections of more than 50 volts shall have a positive means of disconnect adjacent to and in sight from the equipment served. A 0 volt receptacle shall be located within 25 feet (720 mm) of the equipment for service and maintenance purposes. The receptacle need not be located on the same level as the equipment. Low-voltage wiring of 50 volts or less within a structure shall be installed in a manner to prevent physical damage. 3.2 Conceal. It is unlawful to conceal cracks, holes, or other imperfections in materials by welding, brazing, or soldering, by using therein or thereon paint, wax, tar, solvent cement, other leak-sealing or repair agent. 3.0 Condensate Wastes and Control. 3. Condensate Disposal. Condensate from air washers, air-cooling coils, fuel-burning condensing appliances, and the overflow from evaporative coolers and similar watersupplied equipment or similar air-conditioning equipment shall be collected and discharged to an approved plumbing fixture or disposal area. Where discharged into the drainage system, equipment shall drain by means of an indirect waste pipe. The waste pipe shall have a slope of not less than 8 inch per foot (0.4 mm/m) or percent slope and shall be of approved corrosion-resistant material not smaller than the outlet size as required in accordance with either Section 3.3 or Section 3.4 for air-cooling coils or condensing fuel-burning appliances, respectively. Condensate or wastewater shall not drain over a public way. 3.2 Condensate Control. Where a cooling coil or cooling unit is located in an attic or furred space where damage is capable of resulting from condensate overflow, an additional watertight pan of corrosion-resistant metal shall be installed beneath the cooling coil or unit top to catch the overflow condensate due to a clogged primary condensate drain, or one pan with a standing overflow and a separate secondary drain shall be permitted to be provided in lieu of the secondary drain pan. The additional pan or the standing overflow shall be provided with a drain pipe, not less than 3 4 of an inch (20 mm) nominal pipe size, discharging at a point that is readily observed. This requirement is in addition to the requirements in Section 3.3 and Section 3.4. 3.3 Condensate Waste Sizing. Condensate waste pipes from air-cooling coils shall be sized in accordance with equipment capacity as specified in Table 3.3. TABLE 3.3 MINIMUM CONDENSATE PIPE SIZE EQUIPMENT CAPACITY MINIMUM CONDENSATE PIPE DIAMETER TONS OF REFRIGERATION (inches) Up to 20 3 4 2 40 4 90 4 9 5 2 250 2 For SI units: inch = 25 mm, ton of refrigeration = 3.52 kw 3.0 Workmanship. 3. General. Design, construction, and workmanship shall comply with accepted engineering practices and shall be of such character as to secure the results sought to be obtained by this code. The size of condensate waste pipes may be is for one unit or a combination of units, or as recommended by the manufacturer. The capacity of waste pipes assumes a 8 inch per foot (0.4 mm/m) or percent slope, with the pipe running threequarters full at the following conditions:. 2 UNIFORM MECHANICAL CODE
Outside Air 20% Room Air 80% DB WB DB WB 90 F 73 F 75 F 2.5 F For SI units: t/ C=(t/ F-32)/.8 Condensate drain sizing for other slopes or other conditions shall be approved by the Authority Having Jurisdiction. 3.4 Fuel-Burning Appliance Condensate Drains. Condensate drain lines from individual fuel-burning condensing appliances shall be sized according to as required by the manufacturer s recommendations instructions. Condensate drain lines serving more than one appliance shall be approved by the Authority Having Jurisdiction prior to installation. 3.5 Condensate Waste. Where the condensate waste from air-conditioning coils discharges by direct connection to a lavatory tailpiece or to an approved accessible inlet on a bathtub overflow, the connection shall be located in the area controlled by the same person controlling the air-conditioned space. 3. Point of Discharge. Air-conditioning condensate waste pipes shall connect indirectly to the drainage system through an airgap or airbreak to properly trapped and vented receptors, dry wells, leach pits, or the tailpiece of plumbing fixtures. 3.7 Plastic Fittings. Female PVC screwed fittings shall be used with plastic male fittings and plastic male threads only. 33.0 Personnel Protection. 33. General. A metal guard shall be provided around exposed flywheels, fans, pulleys, belts, and moving machinery that are portions of a heating, ventilating, or refrigerating system. 34.0 Heating or Cooling Air System. 34. Source. A heating or cooling air system shall be provided with return air, outside air, or both. A heating or cooling air system regulated by this code and designed to replace required ventilation shall be arranged to discharge into a conditioned space not less than the amount of outside air specified in Chapter 4. 34.2 Air Filters. Air filters shall be installed in a heating, cooling or makeup air system. Such filters shall comply with the standard, Air Filter Units, Test Performance of, that is referenced in Chapter 7, as Class I or II filters. Exception: Systems serving single guest rooms or dwelling units shall not require a listed filter. 34.3 Prohibited Source. Outside or return air for a heating or cooling air system shall not be taken from the following locations: () Closer Less than 0 feet (30 mm) in distance from an appliance vent outlet, a vent opening of a plumbing drainage system, or the discharge outlet of an exhaust fan, unless the outlet is 3 feet (94 mm) above the outside-air inlet. (2) Where it is lless than 0 feet (30 mm) above the surface of an abutting public way, driveway, sidewalk, street, alley, or driveway. (3) A hazardous or insanitary location, or a refrigeration machinery room as defined in this code. (4) From aan area, the volume of which is less than 25 percent of the entire volume served by such system, unless there is a permanent opening to an area the volume of which is equal to 25 percent of the entire volume served. Exception: Such openings where used for a heating or cooling air system in a dwelling unit shall be permitted to be reduced to not less than 50 percent of the required area, provided the balance of the required return air is taken from a room or hall having not less than three doors leading to other rooms served by the furnace. (5) A closet, bathroom, toilet room, or kitchen. () From rrooms or spaces containing a fuel-burning appliance therein. Where such room or space serves as source of return-air. Exceptions: () This shall not apply to fireplaces, fireplace appliances, residential cooking appliances, direct vent appliances, enclosed furnaces, and domestic-type clothes dryers installed within the room or space. (2) This shall not apply to a gravity-type or listed vented wall heating or cooling air system. (3) This shall not apply to a blower-type heating or cooling air system installed in accordance with the following requirements: (a) Where the return air is taken from a room or space having a volume exceeding cubic foot (0.0283 m 3 ) for each 0 Btu/h (2.93 W) fuel input rating of fuel-burning appliances therein. (b) Not less than 75 percent of the supply air is discharged back into the same room or space. (c) Return-air inlets shall not be located within 0 feet (30 mm) from an appliance firebox or draft diverter in the same enclosed room or confined space. 34.4 Return-Air Limitations. Return air from one dwelling unit shall not discharge into another dwelling unit through the heating or cooling air system. 35.0 Water Supply. 35. General. Water supplies supply and backflow protection shall be as required by in accordance with the Uniform Plumbing Code. 3.0 Pipe and Tube Hangers and Supports. 3. General. Piping and tubing shall be supported in accordance with this section, the manufacturer s installation instructions, and as required by in accordance with the Authority Having Jurisdiction. UNIFORM MECHANICAL CODE 27
3. Suspended Piping. Suspended piping shall be supported at intervals not to exceed those shown in Table 3.. 3.23 Piping Support. Piping shall be supported in such a manner as to maintain its alignment and prevent sagging. 3.34 Strength. Hangers and anchors shall be of sufficient strength to support the weight of the pipe and its contents. Piping shall be isolated from incompatible materials. 3.45 Hanger Rod Sizes. Hanger rod sizes shall not be not smaller than those shown in Table 3.45. TABLE 3.45 HANGER ROD SIZES PIPE AND TUBE SIZE ROD SIZES (inches) (inches) 2-4 3 /8 5-8 2 0-5 8 For SI units: inch = 25.4 mm 3.5 Gas Piping. Gas piping shall be supported by metal straps or hooks at intervals not to exceed those shown in Table 3.2..25.. 3.7 In Ground. Piping and tubing in the ground shall be laid on a firm bed for its entire length except where otherwise approved by the Authority Having Jurisdiction. Asbestoscement piping shall be provided with adequate approved thrust blocking. 37.0 Balancing. 37. General. Heating, ventilating, and air-conditioning systems (including hydronic systems) shall be balanced in accordance with one of the following methods: () AABC National Standards for Total System Balance (2) ACCA Manual B (3) ASHRAE (4) NEBB Procedural Standards for Testing Adjusting Balancing of Environmental Systems (5) SMACNA HVAC Systems Testing, Adjusting, and Balancing 3..2 Impact Resistance Test. Upon request by the Authority Having Jurisdiction, louvers protecting intake and exhaust ventilation ducts that are not fixed in the open position and located within 30 feet (944 mm) of the grade shall be tested for impact resistance in accordance with AMCA 540. 39.0 Protection of Piping, Materials, and Structures. 39. General. Piping passing under or through walls shall be protected from breakage. Piping passing through or under cinders or other corrosive materials shall be protected from external corrosion in an approved manner. Approved provisions shall be made for expansion of hot water piping. Voids around piping passing through concrete floors on the ground shall be sealed. 320.0 Sleeves for Piping. 320. General. Sleeves shall be provided to protect piping through concrete and masonry walls and concrete floors. Exception: Sleeves shall not be required where openings are drilled or bored. 320.2 Bearing. Piping through concrete or masonry walls shall not be subject to a load from building construction. 320.3 Sealing. In exterior walls, annular space between sleeves and pipes shall be sealed and made water-tight, as approved by the Authority Having Jurisdiction. A penetration through fire-resistive construction shall be in accordance with the building code and applicable standards referenced in Table 70.0. 320.4 Through Firewall. A pipe sleeve through a firewall shall have the space around the pipe completely sealed with an approved fire-resistive material in accordance with other codes. 32.0 Cutting Structure. 32. General. A structural member weakened or impaired by cutting, notching, or otherwise shall be reinforced, repaired, or replaced so as to be left in a safe structural condition in accordance with the requirements of the building code. 3.0 Louvers in Hurricane Prone Regions. 3. General. Louvers located in areas within hurricaneprone regions that are within mile (.2 km) of the coastal mean high water line where the basic wind speed is 0 miles per hour (mi/h) (9.2 m/s) or greater; or portions of hurricane-prone regions where the basic wind speed is 0 mi/h (53. m/s) or greater; or Hawaii, as described in ASCE 7 shall be tested in accordance with Section 3.. and Section 3..2. 3.. Testing. Louvers that protect air intake or exhaust openings shall be tested in accordance with AMCA 550 for resistance to wind-driven rain. 322.0 Ratproofing. 322. General. Mechanical system shall be constructed in such a manner that rats cannot enter a building by following the duct work from the outside into the building. 322.2 Ductwork or Pipes. In or on buildings where openings have been made in walls, floors, or ceilings for the passage of ductwork or pipes, such openings shall be closed and protected by the installation of approved metal collars securely fastened to the adjoining structure. 28 UNIFORM MECHANICAL CODE
TYPE OF PROTECTION 4 Applied to the Combustible Material Unless Otherwise Specified and Covering All Surfaces within the Distance Specified as the Required Clearance with No Protection (Thicknesses Are Minimum) TABLE 303.3(a) CLEARANCES, IN INCHES, WITH SPECIFIED FORMS OF PROTECTION, 2 WHERE THE STANDARD CLEARANCE IN TABLE 303.4 WITH NO PROTECTION IS: 3 (inches) (inches) (inches) 9 (inches) (inches) ABOVE SIDES AND REAR CHIMNEY OR VENT ABOVE SIDES AND REAR CHIMNEY OR VENT ABOVE SIDES AND REAR CHIMNEY OR VENT ABOVE SIDES AND REAR CHIMNEY OR VENT (a) 4"inch insulating millboard spaced out "inch 3 30 30 5 9 9 3 2 3 (b) 0.03"inch (No. 28 manufacturer s standard gauge) steel sheet on 4"inch insulating millboard 24 24 9 9 4 3 2 2 (c) 0.03"inch (No. 28 manufacturer s standard gauge) steel sheet spaced out "inch 3 9 9 4 4 2 2 2 (d) 0.03"inch (No. 28 manufacturer s standard gauge) steel sheet on 8"inch insulating millboard spaced out "inch 3 9 9 4 4 2 2 2 (e) 2"inch insulating cement covering on heating appliance 3 9 4 9 2 (f) 4"inch insulating millboard on " inch mineral fiber batts reinforced with wire mesh or equivalent 4 4 4 2 2 2 (g) 0.027"inch (No. 22 manufacturer s standard gauge) steel sheet on " inch mineral fiber batts reinforced with wire or equivalent 4 3 3 2 2 2 2 2 2 (h) 4"inch insulating millboard 3 3 3 9 4 4 4 For SI units: inch = 25.4 mm For appliances complying with Section 303.3 and Section 303.4 Except for the protection described in (4), all clearances shall be measured from the outer surface of the appliance to the combustible material, disregarding any an intervening protection applied to the combustible material. 3 Spacers shall be of noncombustible material. Insulating millboard is a factory-made product formed of noncombustible materials, normally fibers, and having a thermal conductivity of Btu-inch per square foot per degree Fahrenheit [.73 W/(m K)] or less.. Dimension shall not be not less than the required clearance with no protection set forth in Table 303.4 and Table 303.3(b2) and in section applying to various types of appliances. 2. Dimension shall be not less than the reduced clearance set forth in Table 303.3(a) 3. Dimension shall not be not less that than the clearance required for dimension A. FIGURE 303.3 ExTENT OF PROTECTION REQUIRED TO REDUCE CLEARANCES APPLIANCE, CHIMNEY, OR VENT S. UNIFORM MECHANICAL CODE 29
TABLE 303.3(b2) CHIMNEY AND VENT CLEARANCES COMBUSTIBLE MATERIALS MINIMUM CLEARANCE DESCRIPTION OF APPLIANCES (Inches) RESIDENTIAL-TYPE APPLIANCES SINGLE-WALL METAL PIPE S 2 Gas appliances without draft hoods Electric, gas, and oil incinerators Oil and solid-fuel appliances Unlisted gas appliances with draft hoods 9 Boilers and furnaces equipped with listed gas burners and with draft hoods 9 3 Oil appliances listed as suitable approved for use with Type L venting systems (but only when where connected to chimneys) 9 Listed gas appliances with draft hoods TYPE L VENTING SYSTEM PIPING S Gas appliances without draft hoods 9 Electric, gas, and oil incinerators 9 Oil and solid-fuel appliances 9 Unlisted gas appliances with draft hoods Boilers and furnaces equipped with listed gas burners and with draft hoods Oil appliances listed as suitable for use with Type L venting systems 4 Listed gas appliances with draft hoods 5 TYPE B GAS VENT PIPING S Listed gas appliances with draft hoods 5 COMMERCIAL-INDUSTRIAL TYPE APPLIANCES LOW-HEAT APPLIANCES SINGLE-WALL METAL PIPE S 2 Gas, oil, and solid-fuel boilers, furnaces, and water heaters Ranges, restaurant-type Oil unit heaters Unlisted gas unit heaters Listed gas unit heaters with draft hoods Other low-heat industrial appliances MEDIUM-HEAT APPLIANCES SINGLE-WALL METAL PIPE S 2 All gas, oil, and solid-fuel appliances 3 For SI units: inch = 25.4 mm These clearances apply except where the listing of an appliance specifies different clearance, in which case the listed clearance takes precedence. 2 The clearances from connectors to combustible materials shall be permitted to be reduced where the combustible material is protected in accordance with Table 303.3(a). 3 The dimension shall be permitted to be inches (52 mm), provided the maximum flue temperatures entering the draft hood do not exceed 550 F (288 C). 4 Where listed Type L venting system piping is used, the clearance shall be permitted to be in accordance with the venting system listing. 5 Where listed Type B or Type L venting system piping is used, the clearance shall be permitted to be in accordance with the venting system listing. 30 UNIFORM MECHANICAL CODE
SEMIRIGID O.D. 2 FLExIBLE NOMINAL I.D. 3 CAPACITIES FOR VARIOUS LENGTHS IN THOUSANDS Btu/h (BASED ON A PRESSURE DROP OF 0.2 INCH WATER COLUMN) NATURAL GAS OF 00 Btu/ft 3, 4 (feet) 2 2 2 2 3 4 5 (inches) (inches) ALL GAS APPLIANCES RANGES AND CLOTHES DRYERS 3 8 4 40 33 29 27 25 2 3 8 93 7 2 58 5 8 2 9 55 34 5 0 90 80 3 4 404 330 287 2 244 803 573 534 500 SEMIRIGID O.D. 2 FLExIBLE NOMINAL I.D. 3 TABLE 303.3(c3) CAPACITIES OF LISTED METAL APPLIANCE S For use with gas pressures 8-inch or more water column (.99-kpa) For SI units: inch = 25.4 mm, foot = 304.8 mm, 000 British thermal unit per = 0.293 kw, cubic foot = 0.0283 m 3, inch water column = 0.249 kpa Gas connectors are certified by the testing agency as complete assemblies, including the fittings and valves. Capacities shown are based on the use of fittings and valves supplied with the connector. 2 Outside diameter. 3 Internal diameter. 4 For liquefied petroleum gas, use. times the natural gas capacities shown. TABLE 303.3(d4) CAPACITIES OF LISTED METAL APPLIANCE S For use with gas pressures less than 8-inch water column (.99-kpa) CAPACITIES FOR VARIOUS LENGTHS IN THOUSANDS Btu/h (BASED ON A PRESSURE DROP OF 0.2 INCH WATER COLUMN) NATURAL GAS OF 00 Btu/ft 3, 4 (feet) 2 2 2 2 3 4 5 (inches) (inches) ALL GAS APPLIANCES RANGES AND CLOTHES DRYERS 3 8 4 28 23 20 9 7 2 3 8 54 47 44 4 5 8 2 34 0 95 88 82 72 3 57 3 4 285 233 202 8 74 57 47 405 378 353 For SI units: inch = 25.4 mm, foot = 304.8 mm, 000 British thermal unit per = 0.293 kw, cubic foot = 0.0283 m 3, inch water column = 0.249 kpa Gas connectors are certified by the testing agency as complete assemblies, including the fittings and valves. Capacities shown are based on the use of fittings and valves supplied with the connector. 2 Semirigid connector listings are based on the outside diameter. 3 Flexible connector listings are based on nominal diameter. 4 For liquefied petroleum gas, use. times the natural gas capacities shown. UNIFORM MECHANICAL CODE 3
TABLE 303.4 STANDARD INSTALLATION CLEARANCES IN INCHES FOR UNLISTED HEAT-PRODUCING APPLIANCES [NFPA 54: TABLE 0.3.3] see section 303.0 RESIDENTIAL-TYPE APPLIANCES FUEL BOILERS AND WATER HEATERS Steam Boilers 5 pound-force per square inch (psi) Automatic Oil or Water Boilers 250 F Comb. Gas-Oil Water Heaters 200 F Automatic Gas All Water Walled or Jacketed Solid ABOVE TOP OF CASING OR APPLIANCE APPLIANCE TOP AND SIDES OF WARM- AIR BONNET OR PLENUM FRONT FURNACES CENTRAL; OR HEATERS ELECTRIC CENTRAL WARM-AIR FURNACES Gravity, Upflow, Downflow, Horizontal and Duct Warm-Air 250 F ( C) max. Automatic Oil or Comb. Gas-Oil Automatic Gas Solid Electric 2 2 3 2 24 2 3 2 FURNACES FLOOR For Mounting in Combustible Floors Automatic Oil or Comb. Gas-Oil Automatic Gas 3 3 HEAT EXCHANGERS Steam 5 psi max. Hot Water 250 F max. ROOM HEATERS 4 Circulating Type Radiant or Other Type Oil or Solid Gas Oil or Solid Gas Gas with double metal or ceramic back 3 3 3 3 3 24 24 3 3 3 3 3 Fireplace Stove Solid 5 54 5 5 RADIATORS Steam or Hot Water 3 RANGES COOKING STOVES Firing Opp. Side Side Oil 30 7 9 24 Gas 30 7 Solid Clay-Lined Firepot 30 7 24 24 Firepot 30 7 3 3 Electric 30 7 Solid Unlined INCINERATORS Domestic Types 3 8 3 3 COMMERCIAL INDUSTRIAL-TYPE APPLIANCES ANY AND ALL PHYSICAL SIZES ExCEPT AS NOTED BOILERS AND WATER HEATERS 00 cubic feet or less Steam, any pressure 50 psi or less Any size UNIT HEATERS Floor Mounted or Suspended Any Size Suspended 00 cubic feet (2.832 m 3 ) or less Suspended 00 cubic feet (2.832 m 3 ) or less Suspended Over 00 cubic feet (2.832 m 3 ) All Fuels All Fuels FUEL Steam or Hot Water Oil or Comb. Gas-Oil Gas All Fuels All Fuels ABOVE TOP OF CASING OR APPLIANCE APPLIANCE TOP AND SIDES OF WARM- AIR BONNET OR PLENUM 24 FRONT BACK BACK 9 RANGES RESTAURANT-TYPE Floor Mounted All Fuels OTHER LOW-HEAT INDUSTRIAL APPLIANCES Floor Mounted or Suspended 24 SIDES SIDES 9 32 UNIFORM MECHANICAL CODE
TABLE 303.4 (continued) STANDARD INSTALLATION CLEARANCES IN INCHES FOR UNLISTED HEAT-PRODUCING APPLIANCES [NFPA 54: TABLE 0.3.3] see section 303.0 COMMERCIAL INDUSTRIAL-TYPE APPLIANCES ANY AND ALL PHYSICAL SIZES ExCEPT AS NOTED FUEL ABOVE TOP OF CASING OR APPLIANCE APPLIANCE TOP AND SIDES OF WARM- AIR BONNET OR PLENUM FRONT BOILERS AND WATER HEATERS Over 50 psi All Fuels 9 3 3 Over 00 cubic feet OTHER MEDIUM-HEAT INDUSTRIAL Appliances All Sizes All Fuels 3 9 3 3 INCINERATORS All Sizes 9 3 3 INDUSTRIAL-TYPE HIGH-HEAT APPLIANCES HIGH-HEAT INDUSTRIAL APPLIANCES All Sizes All Fuels 0 30 0 0 For SI units: inch = 25.4 mm, pound-force per square inch =.8947 kpa, cubic foot = 0.0283 m 3, t/ C = (t/ F-32)/.8 The minimum dimension shall be that necessary for servicing the appliance, including access for cleaning and normal care, tube removal, etc. 2 For a listed oil, combination gas-oil, gas, or electric furnace, this dimension shall be permitted to be 2 inches (5 mm) where the furnace limit control cannot be set exceeding than 250 F ( C), or this dimension shall be permitted to be inch (25.4 mm) if where the limit control cannot be set exceeding 200 F (93 C), or the appliance shall be marked to indicate that the outlet air temperature cannot exceed 200 F (93 C). 3 The dimension shall be permitted to be inches (52 mm) for an automatically stoker-fired forced-warm-air furnace equipped with 250 F ( C) limit control and with barometric draft control operated by draft intensity and permanently set to limit draft to a maximum not to exceed intensity of 0.3 inch (3.3 mm) water gauge. 4 Unlisted appliances shall be installed on noncombustible floors and may shall be permitted to be installed on protected combustible floors. Heating appliances approved for installation on protected combustible flooring shall be so constructed that flame and hot gases do not come in contact with the appliance base. Protection for combustible floors shall consist of 4 inches (02 mm) hollow masonry covered with sheet metal at least not less than 0.02 of an inch (0.53 mm) thick (No. 24 manufacturer s standard gauge). Masonry shall be permanently fastened in place in an approved manner with the ends unsealed and joints matched so as to provide free circulation of air through the masonry. Floor protection shall extend inches (305 mm) at the sides and rear of the appliance, except that not less than inches (457 mm) shall be required on the appliance-opening side or sides measured horizontally from the edges of the opening. 5 The inch (9 mm) clearance shall be permitted to be reduced to 3 inches (94 mm) where protection equivalent to that provided by footnote through footnote 7 of Table 303.4 is applied to the combustible construction. Steam pipes and hot water heating pipes shall be installed with a clearance of not less than inch (25.4 mm) to all from combustible construction or materials, except that at the points where pipes carrying steam at not over 5 pounds-force per square inch gauge pressure (03.4 kpa) or less or hot water that emerge from a floor, wall, or ceiling, the clearance at the opening through the finish floorboards or wall-ceiling boards shall be permitted to be reduced to not less than /2 of an inch (.7 mm). Each such opening shall be covered with a plate of noncombustible material. Such pipes passing through stock shelving shall be covered with not less than inch (25.4 mm) of approved insulation. Wood boxes or casings enclosing uninsulated steam or hot water heating pipes or wooden covers to recesses in walls in which such uninsulated pipes are placed shall be lined with metal or insulating millboard. Where the temperature of the boiler piping does not exceed 0 F (7 C), the provisions of this table shall not apply. Coverings or insulation used on steam or hot water pipes shall be of material suitable approved for the operating temperature of the system. The insulation or jackets shall be of noncombustible materials, or the insulation or jackets and lap-seal adhesives shall be tested as a composite product. Such composite product shall have a flame-spread rating of not to exceed 25 and a smoke-developed rating not to exceed 50 where tested in accordance with ASTM E 84 or UL 723. 7 To combustible material or metal cabinets. Where the underside of such combustible material or metal cabinet is protected with insulating millboard not less than 4 of an inch (.4 mm) thick covered with sheet metal of not less than 0.03 of an inch (0.33 mm) (No. 28 gauge), the distance shall be permitted to be reduced to 24 inches (0 mm). 8 Clearance above charging door shall be not less than inches (9 mm). 9 Where the appliance is encased in brick, the inch (457 mm) clearance above and at the sides and rear shall be permitted to be reduced to inches (305 mm). 0 Where the appliance is encased in brick, the clearance above shall be permitted to be reduced to 3 inches (94 mm) and at the sides and rear shall be permitted to be reduced to inches (457 mm). A central heating boiler or furnace shall be installed in accordance with the manufacturer's installation instructions, and shall be installed on a floor of noncombustible construction with noncombustible flooring and surface finish and no combustible material against the underside thereof, or on fire-resistive slabs or arches having no combustible material against the underside thereof. Exceptions: () Appliances listed for installation on a combustible floor. (2) Installation on a floor protected in an approved manner. BACK SIDES UNIFORM MECHANICAL CODE 33
MATERIALS TYPES OF JOINTS HORIZONTAL VERTICAL Lead and Oakum 5 feet, except 0 feet where 0 foot lengths are Base and each floor, not to exceed 5 feet installed,2,3 Cast Compression Gasket Every other joint, unless over 4 feet; then support each joint,2,3 Base and each floor, a maximum of not to exceed 5 feet Cast-Iron Hubless Shielded Coupling Every other joint, unless over 4 feet; then support each joint,2,3,4 Copper Tube and Pipe Soldered or Brazed Steel and Brass Pipe for Water DWV Steel, Brass, and Tinned Copper Pipe for Gas Schedule 40 PVC and ABS Threaded or Welded Threaded or Welded ½ inches and smaller, feet; 2 inches and larger, 0 feet ¾ inch and smaller, 0 feet; inch and larger, feet ½ inch, feet; ¾ inch and inch 8 feet; ¼ and larger, 0 feet Solvent Cemented All sizes, 4 feet. Allow for expansion every 30 feet 3 Base and each floor, a maximum of not to exceed 5 feet Each floor, a maximum of not to exceed 0 feet 5 Every other floor, a maximum of not to exceed 25 feet 5 ½ inch, feet; ¾ and inch, 8 feet; ¼ every floor level Base and each floor. Provide mid-story guides. Provide for expansion every 30 feet CPVC Solvent Cemented inch and smaller, 3 feet; ¼ inch and larger, 4 feet Base and each floor. Provide mid-story guides Lead Wiped or Burned Continuous Support A maximum of Not to exceed 4 feet Copper Mechanical In accordance with standards acceptable to the Authority Having Jurisdiction Steel and Brass Mechanical In accordance with standards acceptable to the Authority Having Jurisdiction PEX PEX-AL-PEX PE-AL-PE Polypropylene TABLE 3.2 HANGER AND SUPPORTS Metal insert and metal compression } Metal insert and metal ½ inch, ¾ inch, inch All sizes compression 98 inches } Metal insert and metal ½ inch, ¾ inch, inch All sizes compression 98 inches Fusion weld (socket, inch and smaller, 32 inches; ¼ inches and butt, saddle, electrofusion), threaded (metal larger, 4 feet threads only), or mechanical 32 inches Base and each floor. Provide mid-story guides. Base and each floor. Provide mid-story guides. Base and each floor. Provide mid-story guides. Base and each floor. Provide mid-story guides For SI unit: inch = 25.4 mm, foot = 304.8 mm Support adjacent to joint, a maximum of not to exceed inches (457 mm). 2 Brace at sa maximum of not to exceed 40 feet ( 92 mm) intervals to prevent horizontal movement 3 Support at each horizontal branch connection. 4 Hangers shall not be placed on the coupling 5 Vertical water lines shall be permitted to be supported in accordance with recognized engineering principles with regard to expansion and contraction where first approved by the Authority Having Jurisdiction. 34 UNIFORM MECHANICAL CODE