66324-YIM-B-1004
18 Unitary Products Group
NOTE: To find the BTU input, multiply the number of cubic
feet of gas consumed per hour by the BTU content
of the gas in your particular locality. (Contact your
gas company for this information since it varies
widely from city to city.)
SECURE OWNER'S APPROVAL
When the system is functioning properly, secure the owner's
approval. Show him the location of all disconnect switches
and the thermostat. Teach him how to start and stop the unit
and how to adjust temperature settings within the limitations
of the system. Advise him that the flue exhaust hood surface
and the immediate area will experience high temperatures
during the heating cycle. All unauthorized personnel and
debris must be kept away from this area.
MAINTENANCE
NORMAL MAINTENANCE
Periodic maintenance consists of changing or cleaning filters.
Under some conditions, the main burners should be cleaned.
FILTERS
Inspect once a month. Replace Disposable or clean Perma-
nent Type as necessary. DO NOT replace Permanent Type
with Disposable.
MOTORS
Indoor and outdoor fan motors, along with the combustion
blower are permanently lubricated and require no mainte-
nance.
OUTDOOR COIL
Dirt should not be allowed to accumulate on the outdoor coil
surface or other parts in the air circuit. Cleaning should be as
often as necessary to keep the coil clean. Use a brush, vac-
uum cleaner attachment, or other suitable means. If water is
used to clean the coil, be sure that the power to the unit is
shut off prior to cleaning.
Prior to any of the following maintenance proce-
dures, shut off all power to the unit, to avoid per-
sonal injury.
TABLE 11: GASE RATE - CUBIC FEET PER HOUR
1
1.
EXAMPLE: By actual measurement, it takes 38 seconds for the
hand on the 1-cubic foot dial to make a revolution with just a
100,000 BTUH furnace running. Using this information, locate
38 seconds in the first column of Table 11. Read across to the
column headed “1 Cubic Foot,” where you will see that 95 cubic
feet of gas per hour are consumed by the furnace at that rate.
Multiply 95 x 1050 (the BTU rating of the gas obtained from the
local gas company). The result is 99,750 BTUH, which is close
to the 100,000 BTUH rating of the furnace.
SECONDS
FOR ONE
REV.
SIZE OF TEST DIAL
1/2 CU. FT. 1 CU. FT.
10 180 360
12 150 300
14 129 257
16 113 225
18 100 200
20 90 180
22 82 164
24 75 150
26 69 138
28 64 129
30 60 120
32 56 113
34 53 106
36 50 100
38 47 95
40 45 90
42 43 86
44 41 82
46 39 78
48 37 75
50 36 72
52 35 69
54 34 67
56 32 64
58 31 62
60 30 60
Exercise care when cleaning the coil so that the coil
fins are not damaged.
Do not permit the hot condenser air discharge to be
obstructed by overhanging structures or shrubs.
