TM 10-4520-262-12&P 0007 00
OPERATION IN EXTREME RAIN OR HUMIDITY
When operating in conditions of extreme rain or humidity, it is recommended that the heated air outlet
duct with louver (1) and air supply inlet duct with debris grill (2) be secured to the heater and the ducts
securely connected to the tent. It is further recommended that the optional combustion air inlet pipe (3),
and optional combustion exhaust pipe (4) be used if at all possible. Refer to WP 0066 entitled Additional
Authorized Items List for specific information on these optional items.
Under no circumstances should the heater be positioned in standing water. Heater site should be graded
slightly, if necessary, to insure that water runs away from heater and tent.
Heater will not operate when tilt or grade is greater than 15
degrees, which is a 1.5 foot
drop over a 10 foot span.
Ducts (1)(2), pipes (3)(4), and the heater (5) itself might need to be raised higher off the ground to prevent
water from entering the heater, especially the base of the heater housing. The base contains three sealed
compartments in which the battery, combustion blower, and electronic controller are located. These
compartments must not be submerged in standing water. If the heater is to be raised above ground level,
make sure that water cannot run along ducts or heater control assembly lead and find its way into the
If high winds accompany rain or humidity, additional anchors or tiedowns may be required to prevent
winds from shifting the equipment.
The open ends of the optional combustion air inlet (3) and optional combustion exhaust pipe (4) should
be positioned next to each other, both pointed in the same direction, and pointed away from the prevailing
wind. Under no circumstances should either pipe be allowed to sit in standing water, nor should they be
positioned in such a way as to allow water to enter their open ends. This is most important for the
combustion air inlet pipe (3). Water entering the heater will be trapped in the baffles within the air inlet box
and drain out into the pipe, but excessive amounts of water entering the heater could cause it to shut
down and may damage the heater.
If high winds accompany the rain or humidity, the fuel can stand (6) should be firmly anchored to the
ground. (Tent stakes and line can be used as an improvised anchor and tiedown.)
During refueling and at regular intervals between refueling, the heater (5), its ducts (1)(2), and pipes
(3)(4) should be inspected for a buildup of snow, dust, or sand that would cover the heater or block the
ducts or pipes. Any buildup should be removed.
During refueling and at regular intervals between refueling, the sediment strainer (7) of the heater should
be visually checked for contamination. If dirt or other contamination is present, the sediment strainer
should be serviced in accordance with WP 0020 00 entitled Solenoid Valve and Sediment Strainer
Special care should be used during refueling to prevent water, snow, sand, or dust contamination of fuel,
fuel can, fuel hose, and fuel fittings.