Figure 11.2: Gas Valve Detail
11)Perform a combustion test. Boilers equipped with a concentric vent system have a flue gas sample tap located in the boiler vent collar (under the screw cap). For other vent systems, the sample probe may be inserted into the terminal. If this is not possible, remove the flue temperature sensor and insert the analyzer probe in the sensor opening. For the boiler to operate, this sensor will need to be remain connected to the wiring. If the flue gas sensor is removed, be sure to replace it after combustion testing is complete.
Check CO2 (or O2) and CO at both high and low fire. The boiler may be temporarily locked into high or low fire for 15 minutes as follows:
a)To lock the boiler in high fire, simultaneously press and hold the “Mode” button and “+“ button until the display
flashes “H”, indicating that the boiler has been driven to high fire. After this happens, allow the boiler to operate for approximately 5 minutes before taking combustion readings.
b)To lock the boiler in low fire, simultaneously press and hold the “Mode” button and
flashes “L”, indicating that the boiler has been driven to low fire. After this happens, allow the boiler to operate for approximately 5 minutes before taking combustion readings.
c)Normal modulation of the boiler should return 15 minutes after the boiler is locked in high or low fire.
At both high and low fire, CO readings should be less than 75 PPM. Typical CO2 readings are shown in Table 11.3.
TABLE 11.3: TYPICAL CO2/O2 COMBUSTION
READINGS RANGE
Model | Fuel | %CO2 | %O2 |
|
|
|
|
FCM070 | Natural Gas | 9.4 | 4.4 |
FCM070 | Propane | 10.4 | 5.1 |
|
|
|
|
FCM090 | Natural Gas | 9.5 | 4.3 |
|
|
|
|
FCM090 | Propane | 10.5 | 5.0 |
|
|
|
|
FCM120 | Natural Gas | 9.5 | 4.3 |
|
|
|
|
FCM120 | Propane | 10.5 | 5.0 |
|
|
|
|
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