Lochinvar Power-fin 1701 - Manual (Page 27)

Service Manual
27
2
Maintenance
(continued)
Checking manifold gas pressure
The gas manifold pressure tap for F9 models is located on
the downstream test valve in the manifold assembly
(FIG. 2-3). For B9/M9 models the gas manifold pressure
tap is located on the venturi connection of the gas manifold
assembly (FIG. 2-4). The manifold gas pressure tap can be
accessed by removing the upper left access panel on the
front of the appliance.
Follow the steps below when checking manifold gas
pressure:
1. Turn the appliance power switch to the “OFF” position.
2. Loosen the thumbscrew on the upper left access panel.
Remove the upper left access panel.
3. Remove the screws along the front and rear edge of the
top outer jacket panel. Disconnect the 2-pin connector
hanging from the top panel cover inside the unit.
Remove the top outer jacket panel.
4. On F9 models remove the 1/8" hex plug from the tap
on the downstream test valve. Install a fitting in the tap
to connect a manometer to read manifold gas pressure.
Place the tubing of the manometer over the fitting.
On B9/M9 models, loosen the set screw on the venturi
connection of the gas manifold assembly one full turn
from inside the pressure tap to read manifold gas
pressure. Place the tubing of the manometer over the
the tap once the set screw is loosened.
5. Turn the appliance power switch to the “ON” position.
6. Place the appliance into the active position by pressing
the ENTER/RESET button on the display board (see
page 5) until HTR:Standby appears in the display
window.
7. Locate the pinhole button below the ENTER/RESET
button (see page 5). Press the button once and hold for
five (5) seconds to place the appliance into Service
Mode. In Service Mode the appliance will fire and
operate at 100% of rate.
8. As the appliance comes on and fires, record the inches
of water column of displacement on both sides of the
manometer. The sum of these two readings will be the
gas manifold pressure. Reference Table 2B - Gas
Manifold Pressure Chart for the proper measurement.
9. This is a reference pressure only and is not field
adjustable. An appliance supplied with the required
minimum gas supply pressure will operate at the
correct manifold gas pressure.
Figure 2-3_Gas Train Assembly F9
Figure 2-4_Gas Train Assembly B9/M9
Firing Control /
Model No.
Natural Gas
Water Column
(w.c.)
LP Gas
Water Column
(w.c.)
F9: 502 - 1302 +3.2 +10.0
B9: 1501 -4.5 to -5.4 -3.2 to 3.8
B9: 1701 -5.9 to -6.4 -3.4 to -4.0
B9: 2001 -3.5 to -4.0 -1.7 to -2.4
M9: 502 -8.3 -9.7
M9: 752 -4.6 -5.5
M9: 1002 -7.1 -9.3
M9: 1302 -6.8 -9.5
M9: 1501 -3.9 to -4.6 -2.1 to -2.6
M9: 1701 -4.9 to -5.9 -2.1 to -2.6
M9: 2001 -3.9 to -4.6 -2.1 to -2.6
Table 2B_Gas Manifold Pressure Chart