CHAPTER 1
INTRODUCTION
Section I. GENERAL
1-1. Scope
This manual is for your use in operating and maintaining Space Heaters, Preway Inc. Models 444-3-A, 444-3-ABJ, 444-
2ABEX, 444-4A, 441-4ABJ, 444-4ABJ, and Montag Model SH-70B.
1-2. Maintenance Forms and Records
Maintenance forms and records that you are required to use are explained in TM 38-750.
1-3. Reporting of Errors
You can improve this manual by calling attention to errors and by recommending improvements, using DA Form 2028
(Recommended Changes to Publications}, or by a letter, and mail directly to Commanding General, U.S. Army Mobility
Equipment Command, ATTN: AMSME-MPP, 4300 Goodfellow Boulevard, St. Louis, Mo.63120. A reply will be
furnished directly to you.
1-4. Equipment Serviceability Criteria (ESC)
This equipment is not covered by an ESC.
1-5. Destruction of Army Materiel to Prevent Enemy Use
For information pertaining to the destruction of this equipment to prevent enemy use, refer to TM 750-244-3.
1-6. Administrative Storage
For information relative to the administrative storage of this equipment, refer to TM 740-90-1.
Section II. DESCRIPTION AND DATA
1-7. Description
a. General. The Preway Models 444-3-ABJ, 444-2-ABEX, 444-4A, 444-4ABJ and Montag Model SH-70B Space
Heaters (fig. 1-1 and 1-2) are fuel oil burning, non-electric, high radiant type heaters having an output capacity of 70,000
British Thermal Units (BTU) per hour. Preway Model 441-4ABJ has an output capacity of 50,000 BTU per hour. These
space heater models are supplied complete with stove pipe, T-joint, draft regulator, adjustable pitch roof jack assembly,
circulating fan, and are designed for floor installation. Preway basic unit) Models 444-3A and 444-4A space heaters
come equipped without air circulating fan and adjustable pitch roof jack. This basic stove unit is interchangeable with the
above mentioned models.
b. Fuel System. Fuel oil is supplied to the control valve from a standard military rectangular 5 gallon fuel can,
which is hung on the left side of the heater frame. A siphon starts the fuel flowing from the can to the control valve. The
fuel can is easily removed, permitting uninterrupted burner operation during fuel can servicing.
c. Combustion Chamber. The combustion chamber consists of a metal drum surrounded by a perforated metal
guard and is mounted on a metal base. The burner is a vaporizing pot type which vaporizes the oil, mixing it with the
combustion air. Combustion air is drawn into the drum through an opening in the bottom.
d. Controls. The fuel control valve is of the manually adjusted type. Fuel burning can be varied from a low pilot
flame to maximum output.
e. Circulating Fan. A 650 CFM fan is attached to the lower end of the ventilator tube of the roof jack to improve
warm air distribution and for summer ventilation. The fan motor is a sealed bearing type requiring no lubrication.
f. Roof Jack Assembly. The roof jack assembly serves both as an exhaust for the heater flue gases, and as a
ventilator for the building. The lower end of the ventilator tube is equipped with an adjustable damper which controls the
amount of air passing up the tube.
1-1
