[Code of Federal Regulations]

[Title 49, Volume 5]

[Revised as of October 1, 2005]

From the U.S. Government Printing Office via GPO Access

[CITE: 49CFR393.77]



[Page 422-424]

 

                        TITLE 49--TRANSPORTATION

 

                      DEPARTMENT OF TRANSPORTATION

 

PART 393_PARTS AND ACCESSORIES NECESSARY FOR SAFE OPERATION--Table of 

Contents

 

              Subpart G_Miscellaneous Parts and Accessories

 

Sec. 393.77  Heaters.



    On every motor vehicle, every heater shall comply with the following 

requirements:

    (a) Prohibited types of heaters. The installation or use of the 

following types of heaters is prohibited:

    (1) Exhaust heaters. Any type of exhaust heater in which the engine 

exhaust gases are conducted into or through any space occupied by 

persons or any heater which conducts engine compartment air into any 

such space.

    (2) Unenclosed flame heaters. Any type of heater employing a flame 

which is not fully enclosed, except that such heaters are not prohibited 

when used for heating the cargo of tank motor vehicles.

    (3) Heaters permitting fuel leakage. Any type of heater from the 

burner of which there could be spillage or leakage of fuel upon the 

tilting or overturning of the vehicle in which it is mounted.

    (4) Heaters permitting air contamination. Any heater taking air, 

heated or to be heated, from the engine compartment or from direct 

contact with any portion of the exhaust system; or any heater taking air 

in ducts from the outside atmosphere to be conveyed through the engine 

compartment, unless said ducts are so constructed and installed as to 

prevent contamination of the air so conveyed by exhaust or engine 

compartment gases.

    (5) Solid fuel heaters except wood charcoal. Any stove or other 

heater employing solid fuel except wood charcoal.

    (6) Portable heaters. Portable heaters shall not be used in any 

space occupied by persons except the cargo space of motor vehicles which 

are being loaded or unloaded.

    (b) Heater specifications. All heaters shall comply with the 

following specifications:

    (1) Heating elements, protection. Every heater shall be so located 

or protected as to prevent contact therewith by occupants, unless the 

surface temperature of the protecting grilles or of any exposed portions 

of the heaters, inclusive of exhaust stacks, pipes, or conduits shall be 

lower than would cause contact burns. Adequate protection shall be 

afforded against igniting parts of the vehicle or burning occupants by 

direct radiation. Wood charcoal heaters shall be enclosed within a metal 

barrel, drum, or similar protective enclosure which enclosure shall be 

provided with a securely fastened cover.

    (2) Moving parts, guards. Effective guards shall be provided for the 

protection of passengers or occupants against injury by fans, belts, or 

any other moving parts.

    (3) Heaters, secured. Every heater and every heater enclosure shall 

be securely fastened to the vehicle in a substantial manner so as to 

provide against relative motion within the vehicle during normal usage 

or in the event the vehicle overturns. Every heater shall be so 

designed, constructed, and mounted as to minimize the likelihood of 

disassembly of any of



[[Page 423]]



its parts, including exhaust stacks, pipes, or conduits, upon overturn 

of the vehicle in or on which it is mounted. Wood charcoal heaters shall 

be secured against relative motion within the enclosure required by 

paragraph (c)(1) of this section, and the enclosure shall be securely 

fastened to the motor vehicle.

    (4) Relative motion between fuel tank and heater. When either in 

normal operation or in the event of overturn, there is or is likely to 

be relative motion between the fuel tank for a heater and the heater, or 

between either of such units and the fuel lines between them, a suitable 

means shall be provided at the point of greatest relative motion so as 

to allow this motion without causing failure of the fuel lines.

    (5) Operating controls to be protected. On every bus designed to 

transport more than 15 passengers, including the driver, means shall be 

provided to prevent unauthorized persons from tampering with the 

operating controls. Such means may include remote control by the driver; 

installation of controls at inaccessible places; control of adjustments 

by key or keys; enclosure of controls in a locked space, locking of 

controls, or other means of accomplishing this purpose.

    (6) Heater hoses. Hoses for all hot water and steam heater systems 

shall be specifically designed and constructed for that purpose.

    (7) Electrical apparatus. Every heater employing any electrical 

apparatus shall be equipped with electrical conductors, switches, 

connectors, and other electrical parts of ample current-carrying 

capacity to provide against overheating; any electric motor employed in 

any heater shall be of adequate size and so located that it will not be 

overheated; electrical circuits shall be provided with fuses and/or 

circuit breakers to provide against electrical overloading; and all 

electrical conductors employed in or leading to any heater shall be 

secured against dangling, chafing, and rubbing and shall have suitable 

protection against any other condition likely to produce short or open 

circuits.



    Note: Electrical parts certified as proper for use by Underwriters' 

Laboratories, Inc., shall be deemed to comply with the foregoing 

requirements.



    (8) Storage battery caps. If a separate storage battery is located 

within the personnel or cargo space, such battery shall be securely 

mounted and equipped with nonspill filler caps.

    (9) Combustion heater exhaust construction. Every heater employing 

the combustion of oil, gas, liquefied petroleum gas, or any other 

combustible material shall be provided with substantial means of 

conducting the products of combustion to the outside of the vehicle: 

Provided, however, That this requirement shall not apply to heaters used 

solely to heat the cargo space of motor vehicles where such motor 

vehicles or heaters are equipped with means specifically designed and 

maintained so that the carbon monoxide concentration will never exceed 

0.2 percent in the cargo space. The exhaust pipe, stack, or conduit if 

required shall be sufficiently substantial and so secured as to provide 

reasonable assurance against leakage or discharge of products of 

combustion within the vehicle and, if necessary, shall be so insulated 

as to make unlikely the burning or charring of parts of the vehicle by 

radiation or by direct contact. The place of discharge of the products 

of combustion to the atmosphere and the means of discharge of such 

products shall be such as to minimize the likelihood of their reentry 

into the vehicle under all operating conditions.

    (10) Combustion chamber construction. The design and construction of 

any combustion-type heater except cargo space heaters permitted by the 

proviso of paragraph (c)(9) of this section and unenclosed flame heaters 

used for heating cargo of tank motor vehicles shall be such as to 

provide against the leakage of products of combustion into air to be 

heated and circulated. The material employed in combustion chambers 

shall be such as to provide against leakage because of corrosion, 

oxidation, or other deterioration. Joints between combustion chambers 

and the air chambers with which they are in thermal and mechanical 

contact shall be so designed and constructed as to prevent leakage 

between the chambers and the materials employed in such joints shall 

have melting points substantially higher than the maximum



[[Page 424]]



temperatures likely to be attained at the points of jointure.

    (11) Heater fuel tank location. Every bus designed to transport more 

than 15 passengers, including the driver, with heaters of the combustion 

type shall have fuel tanks therefor located outside of and lower than 

the passenger space. When necessary, suitable protection shall be 

afforded by shielding or other means against the puncturing of any such 

tank or its connections by flying stones or other objects.

    (12) Heater, automatic fuel control. Gravity or siphon feed shall 

not be permitted for heaters using liquid fuels. Heaters using liquid 

fuels shall be equipped with automatic means for shutting off the fuel 

or for reducing such flow of fuel to the smallest practicable magnitude, 

in the event of overturn of the vehicle. Heaters using liquefied 

petroleum gas as fuel shall have the fuel line equipped with automatic 

means at the source of supply for shutting off the fuel in the event of 

separation, breakage, or disconnection of any of the fuel lines between 

the supply source and the heater.

    (13) ``Tell-tale'' indicators. Heaters subject to paragraph (c)(14) 

of this section and not provided with automatic controls shall be 

provided with ``tell-tale'' means to indicate to the driver that the 

heater is properly functioning. This requirement shall not apply to 

heaters used solely for the cargo space in semitrailers or full 

trailers.

    (14) Shut-off control. Automatic means, or manual means if the 

control is readily accessible to the driver without moving from the 

driver's seat, shall be provided to shut off the fuel and electrical 

supply in case of failure of the heater to function for any reason, or 

in case the heater should function improperly or overheat. This 

requirement shall not apply to wood charcoal heaters or to heaters used 

solely to heat the contents of cargo tank motor vehicles, but wood 

charcoal heaters must be provided with a controlled method of regulating 

the flow of combustion air.

    (15) Certification required. Every combustion-type heater, except 

wood charcoal heaters, the date of manufacture of which is subsequent to 

December 31, 1952, and every wood charcoal heater, the date of 

manufacture of which is subsequent to September 1, 1953, shall be marked 

plainly to indicate the type of service for which such heater is 

designed and with a certification by the manufacturer that the heater 

meets the applicable requirements for such use. For example, ``Meets 

I.C.C. Bus Heater Requirements,'' Meets I.C.C. Flue-Vented Cargo Space 

Heater Requirements,'' and after December 31, 1967, such certification 

shall read ``Meets FMCSA Bus Heater Requirements,'' ``Meets FMCSA Flue-

Vented Cargo Space Heater Requirements,'' etc.

    (i) Exception. The certification for a catalytic heater which is 

used in transporting flammable liquid or gas shall be as prescribed 

under Sec. 177.834(1) of this title.



[33 FR 19735, Dec. 25, 1968, as amended at 40 FR 51198, Nov. 4, 1975; 53 

FR 49401, Dec. 7, 1988]