NPFC - WW-F-2743
FURNACES, WARM AIR AND HEATERS, UNIT, FORCED AIR CIRCULATION, OIL - AND GAS - FIRED
|Publication Date:||27 May 1998|
This specification covers self-contained, forced-circulation, air heating units designed to distribute warm air for heating purposes either through a duct system for central furnaces or by direct diffusion for unit heaters.
Types, styles, groups, and burner kinds.
The heating units will be of the following types, styles, groups, and burner kinds, as specified (see 6.2):
Type I -Central furnace. Type II - Unit heater. Style A - Upflow, high-boy. Style B - Upflow, low-boy. Style C - Downflow. Style D - Horizontal flow.
Beneficial comments, recommendations, additions, deletions, clarifications, etc. and any data which may improve this document should be sent to: Commanding Officer (Code 15E2), Naval Construction Battalion Center, 1000 23rd Avenue, Port Hueneme, CA 93043-4301, by using the Standardization Document Improvement Proposal (DD Form 1426) appearing at the end of this document or by letter.
For the purpose of defining requirements, the furnaces and space heaters covered by this specification are classified under the following groups based on the thermal input in British thermal units per hour (Btu/hr (watt (W)) (see 3.8.1 and 6.2).
Group 1 - 22,000 to 225,000 Btu/hr (6 448 W) to 65 940 W) input. Group 2 - 225,001 to 400,000 Btu/hr (65 941 W to 117 228 W) input. Group 3 - Over 400,000 Btu/hr (117 228 W) input.
Burners furnished on the furnaces and unit heaters will be of the following kinds, as specified (see 6.2). (Burner kinds HO, GLO, and GHO will apply to group 3 units only.)
Burner kind LO - Light-oil-fired (grade 2). Burner kind G - Gas-fired (natural, manufactured, mixed, or liquefied petroleum gas), as specified (see 6.2). Burner kind HO - Heavy-oil-fired (grade 4). Burner kind GLO - Combination gas-and light-oil-fired. Burner kind GHO - Combination gas - and heavy - oil - fired (grade 4).
Central furnaces are intended for installation in family housing or nonfamily housing structures primarily to supply heated air through a sheet metal duct system. Type I furnaces of the upflow... View More
Central furnaces are intended for installation in family housing or nonfamily housing structures primarily to supply heated air through a sheet metal duct system. Type I furnaces of the upflow style shall be suitable for alcove or closet installation in residential structures. Type I furnaces of the horizontal style shall be suitable for alcove installation in residential structures. Unit heaters are intended primarily for installation in such nonfamily structures as warehouses, industrial shops, auditoriums, hangars, and gymnasiums where warm air will be directly diffused into the space in which the heater is located. Downflow furnaces can be used to an advantage with under-floor duct systems in structures having no basements for central-furnace location. Downflow furnaces are also referred to as counterflow units since the heated-air path runs in a direction counter to the flue gas passage.View Less