Unit Components - Modine Manufacturing HD Manual

CONTROL OPERATING SEQUENCE / UNIT COMPONENTS
CONTROL OPERATING SEQUENCE
Upon a call for heat from the thermostat, power is supplied to
the power exhauster motor. The unit will go through a purge
period and then the direct spark igniter will be energized. At the
same time, the main valve in the combination control valve will
open to allow gas to flow to the burners. If the fan motor has not
Figure 18.1 - Major Gas, Electrical Service, Safety and Other Components
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1. Power Exhauster
2. Pressure Switch
3. Integrated Direct Spark Control Board
4. Combination Gas Control
Table 18.1 - Control Options
Single-Stage, Direct Spark Ignition, 100% Shut-Off with Continuous Retry
- Utilizes a single-stage combination gas control with ignition control. Gas is lit with a
direct spark igniter on call for heat.
Two-Stage, Direct Spark Ignition, 100% Shut-Off with Continuous Retry
- Utilizes a two-stage combination gas control with built-in ignition control.
Firing rate is 100% and 50% of full rated input. Gas is lit with a direct spark
igniter on call for heat.
Table 18.2 - Propeller Model HD Performance
Btu/Hr Input
30,000
Btu/Hr Output 24,900
Entering Airflow (CFM) @ 70°F
Outlet Velocity (FPM)
Air Temp. Rise (°F)
Max. Mounting Height (Ft.)
Heat Throw (Ft.)
(@ Max Mtg Ht.)
Motor Type
Motor HP
Motor RPM
18
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5. Control Transformer
6. Flame Sensor (hidden)
7. Flame Rollout Switch
8. Auto Reset Limit Control (hidden)
Control Description
Model HD Sizes
30 45 60 75
45,000 60,000 75,000 100,000 125,000
36,900 49,200 62,250
505 720 990 1160
523 725 653 769
44 46 45 48
10 10 12 14
25 27 36 38
SP SP PSC PSC
1/15 1/15 1/12 1/12
1550 1550 1625 1625
all ready started it will start shortly. If a flame is not sensed for
any reason the main valve will close and there will be a short
purge period before ignition is tried again. If the flame is not
sensed after 4 tries, there will be at least a 1 hour wait before
ignition is tried again.
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Control Service
Code No. Voltage
11 115V
21 115V
12 115V
22 115V
Table 18.3 - Blower Model HDB Performance
100 125
Btu/Hr Input 
82,000 102,500 Btu/Hr Output 
1490 1980 Entering Airflow Range (CFM)
565 747 Outlet Velocity (FPM)
Air Temp. Rise (°F)
50 47
12 16
Max. Mounting Height (Ft.) ‚
Heat Throw (Ft.)
42 56
(@ Max Mtg Ht.) ‚
Motor Type ƒ
SP PSC
Motor HP
1/6 1/8
1050 1625 Motor RPM
 Ratings shown are for elevations up to 2,000 feet. For elevations above 2,000 feet,
ratings should be reduced at the rate of 4% for each 1,000 feet above sea level. (In
Canada see rating plate.) Reduction of ratings requires use of a high altitude kit.
‚ Data taken at 55°F air temperature rise. At 65°F ambient and unit fired at full-rated
input. Mounting height as measured from bottom of unit, and without deflector hoods.
6-583.15
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9. Direct Spark Igniter (hidden)
10. Manual Reset Control (hidden,
propeller 100-125 only)
Thermostat Type of
Voltage Gas
24V Natural
24V Propane
24V Natural
24V Propane
Model HDB Sizes
60 75
60,000 75,000
49,200 61,500
635-1111 794-1389 1140-2116 1235-2058
437-726 546-908
40-70 40-70
7-13 7-16
20-45 24-57
P.S.C. P.S.C.
1/4 1/3
Max 1100 Max 1100 Max 1100
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Model
Size
30-125
30-125
75-125
75-125
100 125
100,000 125,000
82,000 102,500
443-781 488-773
35-65 45-75
8-19 8-17
27-68 27-59
P.S.C. P.S.C.
1/2 1/2
Max 1100