Teledyne Laars Hi-E EPH 300, Руководство пользователя, Страница: 6 / 18

Page 6
NOTE: Gas supply test, stack test, and air flow filter
test should be completed before attempting this test or
making any adjustments.
1. Check supply gas pressure (see Section 3B-2).
2. Check that all ports and tubes are clear that
connect the gas valve and venturi.
3. Check for proper orifice (see Table 2).
4. Attach a manometer or a 1/2 inch (13 mm)
negative pressure gauge between the outlet pres-
sure tap on the gas valve and the venturi (lower)
inlet pressure tap (see Fig. 6).
Figure 6. Checking the Gas Pressure
Table 2. Gas Metering Orifice Size
Natural Gas LP Gas
Orifice Diameter 0.354 in. 0.295 in.
(8.99 mm) (7.49 mm)
Color Code Brass Silver
5. The pressure at the gas valve outlet will be 0.2
inch (5.08 mm) water column (W.C.) less than the
pressure at the venturi (lower) inlet.
6. Take a reading. The ideal range should be between
-0.1 and -0.3 inches (-2.5 and -7.6 mm) W.C.
when the gas valve is energized.
IMPORTANT: Before the gas valve is energized, the
pressure reading will be approximately 2.8 inches (71
mm) W.C. on outdoor units fitted with the standard
vent stack. On indoor installations with vent piping as
long as 60 feet (18 meters [m]), the pressure can be as
low as 2.0 inches (51 mm) W.C.
3A-2. Checking the Supply Gas Pressure
To check the gas supply pressure:
1. Attach one end of a manometer hose to the fitting
on the gas valve (see Fig. 6).
2. Remove threaded cap from T-fitting and replace
with fitting from manometer.