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S
XT I
, O
ERIES
NSTALLATION
PERATION AND
adjustment.
Table 15: Motor Sheave Drive Torque
Specifications
Setscrew Size
Allen Wrench
1/4"
1/8"
5/16"
5/32"
3/8"
3/16"
Table 16: Motor and Blower Bushing Torque
Specifications
Bolt Size (on Bushing)
#10
1/4"
5/16"
3/8"
1/2"
20.4.2 Burner Pressure
1.
A pressure tap is used to measure differential
at the burner and to set high fire gas pressure.
On air handlers equipped with a M611 modu-
lating valve (Model XT-112), the pressure tap is
located on a tee between the M611 valve and
the burner. See Page 39, Figure 22 and Page
68, Figure 37. On air handlers equipped with
the MR212 modulating valve (Models XT-115 -
XT-130), the pressure tap could be located on
the downstream side of the MR212 valve, on a
T-fitting coming off the outlet pressure tap on
the MR212 valve or between the MR212 valve
and the burner. See Page 39, Figure 23 and
Page 67 , Figure 35.
2. Measure the burner pressure with the inlet
manual gas valve off.
- Open the manual shut off located between
the modulating valve and the burner.
- Turn the blower on and record the negative
pressure on a u-tube manometer or gas
pressure gauge. This reading is used for high
fire burner pressure adjustment.
3. After taking the burner pressure reading, tem-
porarily leave the manometer attached to the
1/8" tap. It will be used later to check high fire
gas pressure.
64
S
M
ERVICE
ANUAL
Torque Settings
in
Lbs
ft
Lbs
•
•
87
7.3
120
10.0
290
24.2
Torque Settings
in
Lbs
ft
Lbs
•
•
60
5
108
9
192
16
360
30
720
60
20.5 Gas Piping and Initial Pressure Settings
1.
Perform a pressure test on all gas supply lines
to the air handler per applicable codes.
Make sure to isolate all gas controls before
pressure testing the system.
2. Verify supply pressure does not exceed maxi-
mum rated gas pressure as stated on the rating
plate.
3. Set the supply gas pressure at the step down
regulator (normally outside of the enclosure if
one is installed) according to the nameplate
rating inlet gas pressure specifications.
4. Only after performing steps 1-3 (above), verify
pilot pressure.
•
Place a u-tube manometer or gas pressure
gauge on the tee at the downstream side of
the pilot pressure regulator.
•
Open the main gas valve and close the gas
valve downstream of the MR valve.
•
Set the burner switch to "on" and adjust the
pilot pressure regulator to 1.0 in wc for
natural gas or 0.5 in wc for LPG.
•
Verify that the burner flame control has a
flame signal of 6-8 Vdc. See Page 64,
Figure 34.
FIGURE 34: Fireye Flame Module
Connect
Test Leads
Here
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