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Form I-UDA, P/N 195673 R24, Page 7
4.0 Clearances
and
Dimensions
Clearances
Size
Top Flue Connector Access Panel Non-Access Side Bottom* Rear**
inches mm inches mm inches mm inches mm inches mm inches mm
30 - 125 1 25 6 152 18 457 1 25 1 25 18 457
150 - 400 4 102 6 152 18 457 2 51 1 25 18 457
*Suspend the heater so that the bottom is a minimum of 5 feet (1.5M) above the oor.
** Measure rear clearance from the fan motor.
4.1 Clearances
Units must be installed so that the clearances in the table are provided for combustion
air space, inspection and service, and for proper spacing from combustible construc-
tion. Clearance to combustibles is dened as the minimum distance from the heater
to a surface or object that is necessary to ensure that a surface temperature of 90°F
(50°C) above the surrounding ambient temperature is not exceeded.
FIGURE 2 -
Installing High
Altitude Pressure
Switch required
above 6000 ft
(1830M) elevation
Gas valve adjustment
for high altitude can
only be done after
heater is operating;
see Paragraph 6.1.
Instructions for Changing Pressure Switch
1. In the control compartment, locate the pressure switch.
2. Mark and disconnect the two wires attached to the pressure switch.
3. Disconnect the sensing tubes from the pressure switch.
4. Locate the two screws holding the switch mounting bracket. Remove the screws and the pressure switch. Save
the screws.
5. Using the same screws, install the high altitude pressure switch. Attach the sensing tubes and wires.
Pressure Switch
Model UDAP
Size 30 45 60 75 100 125 150 175 200 225 250 300 350 400
High Altitude Switch P/N 197031 197032 197031 201160
Negative Pressure OFF Setpoint "w.c. 0.35 0.45 0.35 1.05
Label color Purple Pink Purple Brown
Model UDAP-CV with Option AV6 for Common Venting
Size 30 45 60 75 100
High Altitude Switch P/N 197029 197032 196362 196388
Negative Pressure OFF Setpoint "w.c. 0.60 0.45 0.55 0.50
Label color Lt Blue Pink White Orange
Model UDAS
Size 30 45 60 75 100 125 150 175 200 225 250 300 350 400
High Altitude Switch P/N 197029 196388 197030 197031 201160
Differential Pressure OFF Setpoint "w.c. 0.60 0.50 0.40 0.35 1.05
Label color Lt. Blue Orange Green Purple Brown
Adjusting the valve outlet pressure is done after the heater is in operation; follow the
instructions in Paragraph 6.1. Capacities and inputs for derated units are also listed in
Paragraph 6.1.
If the pressure switch needs to be changed, do that before the heater is operated; fol-
low the instructions in FIGURE 2.
Downturn Nozzle Kits,
Option CD 2, 3, or 4
Follow the instructions with the kit to install. Additional length beyond the front of the
unit is shown in FIGURE 3.
U U
With
Option
CD3
With
Option
CD2
or
CD4
UDAP or UDAS
UDAP or UDAS
Downturn nozzles require
4-pt suspension.
FIGURE 3 -
With Optional
Downturn Nozzle
Dimension “U”
-- Applies to both UDAP
and UDAS
Size
Options CD2 and CD4 Option CD3
inches mm inches mm
30, 45 7-1/8 181 12-3/8 314
60, 75 8-5/8 219 15 381
100, 125 12-5/8 321 21-7/8 556
150, 175, 200 11-1/2 292 19-7/8 505
225, 250 14-1/2 368 25-1/8 638
300, 350, 400 18-1/2 470 32 813
In addition, if the heater is being installed at an altitude above 6000 ft (1830M), the
pressure switch will have to be changed. If ordered with the unit as Option DJ20 or
DJ21, the pressure switch is shipped separately for eld installation.
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