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Instructions:
1. Turn off the gas and the power
supply.
2. Remove the 3 screws that hold the
front panel. Lift the panel straight up
and then remove.
3. Remove test port screws (1/8 NPT
tap) with 3/16 Allen wrench located
at gas valve and burner cover.
Install two 1/8 in. barb fittings (field-
supplied). Attach dual port
manometer to the test ports as
shown. Ensure that the manometer
is properly calibrated.
4. Turn on the gas and power supply
to the furnace.
5. Ensure "Set Back" feature has been
deactivated. ("Set Back" feature is
active by default.)
6. With the unit in the Off position,
press the Test Switch at the bottom,
right of PC board until it beeps.
7. Select the correct code for gas type,
altitude, and vent length on the LED
display using ▲ and ▼ buttons.
Refer to the table below.
Table 8: Gas Pressure
Short Vent Lengths:
0 - 7 ft (2 m) + 1 elbow (A1 - A4)
Long Vent lengths:
7 ft (2 m) +1 elbow - 13 ft (4 m) + 3 elbows (A5 - A8)
Code
A1 / A5
0-2,000 ft
Altitude
0-610 m
Manifold test
1.69 in.
pressure - W.C.
(43 mm)
Low
Manifold test
3.8 in.
pressure - W.C.
(96 mm)
High
26
Natural Gas
A2 / A6
A3 / A7
2,001-5,400 ft
5,401-7,800 ft
611-1,646 m
1,647-2,377 m
1.59 in.
1.49 in.
(40 mm)
(38 mm)
3.0 in.
2.7 in.
(76 mm)
(68 mm)
Figure 33
Short Vent Lengths:
0 - 7 ft (2 m) + 1 elbow (L1 - L4)
Long Vent lengths:
7 ft (2 m) +1 elbow - 13 ft (4 m) + 3 elbows (L5 - L8)
A4 / A8
L1 / L5
7,801-10,200 ft
0-2,000 ft
2,378-3,109 m
0-610 m
1.43 in.
3.21 in.
(36 mm)
(82 mm)
2.5 in.
6.4 in.
(62 mm)
(162 mm)
EX38DT Installation and Operation Manual
PCB Test
Switch
Positive
Port
Negative
Port
Propane Gas
L2 / L6
L3 / L7
2,001-5,400 ft
5,401-7,800 ft
611-1,646 m
1,647-2,377 m
3.01 in.
2.85 in.
(76 mm)
(72 mm)
5.6 in.
5.1 in.
(143 mm)
(129 mm)
L4 / L8
7,801-10,200 ft
2,378-3,109 m
2.73 in.
(69 mm)
4.6 in.
(116 mm)
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