Bosch Appliances GWH-345/450-ESR-N, GWH-345/450-ESR-L manual Measuring gas pressure

Installation instructions

3.8Measuring gas pressure

Connecting manometer

BTurn power off.

BShut off gas supply.

B Remove front cover and locate the inlet gas measuring point (see Fig. 27).

BLoosen screw inside test point fitting (do not remove) and connect manometer tube on test point.

Fig. 27 Gas pressure measuring (lower tapping)

Static pressure test

BTurn gas supply on.

BOperate all other gas appliances on same gas piping system at maximum output.

BKeep unit off and record static pressure reading in Table 11.

Operating pressure test

BPress On/Off button to turn heater On.

For this test the unit has to be put in Service Level

BAfter 10 seconds, press and hold the reset button

.

BRotate 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 Service Mode.

BPlace a demand for heat by turning external tank ther- mostat control to maximum for unit to fire at maximum input.

BRecord operating pressure reading in Table 11.

BPress On/Off button to turn heater Off and exit Service Mode.

Note: after verification tighten the screw

iinside 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.

Static Gas Pressure Reading (see Chapter 3.8)

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Operating Gas Pressure Reading (see Chapter 3.8)

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Table 11

3.9Checking restrictor plate size by measuring CO2 level value.

BRemove brass flat head screw on the exhaust collar.

Fig. 28 Measuring port

BInsert CO2 analyzer probe into the measuring point. The tip of the probe should be in the center of the flue pipe. Avoid air gaps between probe and measuring port to avoid inaccurate readings.

BPress On/Off button to turn heater On.

For this test the unit has to be put in Service Level.

BOpen a hot water tap.

BAfter 10 seconds, press and hold the reset button

.

BRotate 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).

BRotate the hot water temperature selector to the maximum.

BThe restrictor size is correct if the CO2 level is within the values as per table 13.

CO2 value (%)

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Table 12

Appliance	CO2 (%)
GWH-345-ESR-N	6.8 - 7.2
GWH-345-ESR-L	7.5 - 8.0
GWH-450-ESR-N	6.5 - 7.0
GWH-450-ESR-L	7.0 - 7.5

Table 13 CO2 levels at max. input

6 720 607 909 25