Bosch GWH 345 ESR-N Manual page 25

3.8 Measuring gas pressure
Connecting manometer
B Turn power off.
B Shut off gas supply.
B Remove front cover and locate the inlet gas
measuring point (see Fig. 29).
B Loosen screw inside test point fitting (do not remove)
and connect manometer tube on test point.
Fig. 29 Gas pressure measuring (lower tapping)
Static pressure test
B Turn gas supply on.
B Keep unit off and record static pressure reading in
Table 11.
Operating pressure test
B Place a demand for heat by turning external tank
thermostat control to maximum for unit to fire at
maximum input.
B Press On/Off button to turn heater On.
For this test the unit has to be put in Diagnostic
Mode.
B After 10 seconds, press and hold the reset button
.
B Rotate the recirculating water temperature selector
(left knob) to the minimum and then to maximum.
B Release the reset button and the display should
show * (blinking).
The unit has now entered Diagnostic Mode.
B Operate all other gas appliances on same gas piping
system at maximum output.
B Record operating pressure reading in Table 11.
B Press On/Off button to turn heater Off and exit
Diagnostic Mode.
Note: after verification tighten the screw
i
inside the test point.
Operating gas pressures lower than 5.5" W.C. for nat-
ural gas or 11" W.C. for LP will result in improper oper-
ation and must be corrected. See Chapter 3.7 for gas
line sizing requirements.
6 720 607 909
Static Gas Pressure Reading (see Chapter 3.8)
enter here: ___________________
Operating Gas Pressure Reading (see Chapter 3.8)
enter here: ___________________
Table 11
Manifold pressure test
B To confirm manifold pressure connect manometer to
upper tapping on gas valve. See Fig. 30.
Fig. 30
B Follow instructions in "operating pressure test" to
place unit into Diagnostic Mode.
B Place a demand for heat by turning external tank
thermostat control to maximum for unit to fire at
maximum input.
B Operate all other gas appliances on same gas piping
system at maximum output.
B Compare manometer values with those found in
Table 12 below.
Gas valve GWH345
pressure in W.C.
Min.
Natural Gas -0.3
Liquid Gas 0.2
Table 12
B Press On/Off button to turn heater Off and exit Diag-
nostic Mode.
Installation instructions
6720607909-34. 1 JS
GWH450
Max. Min. Max.
3.5 0.5 4.0
8.2 0.0 9.0
25