Dunkirk DWB Series - Manual (Page 25)

9.6 Check Combustion
Natural Gas
1.
Measure input. English unitsTurn off gas to all other
appliances.
• Activate some heating zones to dissipate heat.
• Set boiler on high fi re.
• Use ½, 1 or 2 cu ft dial on gas meter. Measure
time required for one or more complete
revolutions. Measure time for 1-2 minutes.
• Calculate input.
Input (MBH) =
3600 x cu ft
seconds
Example: Gas fl ow from
Meter = 2 cu ft
Measured time = 72 seconds
Rate (MBH) =
3600 x 2 cu ft
= 100 MBH
72 seconds
25
Two sampling points are available at top of the boiler, one
for venting and the other for combustion air. To sample:
Open the air/vent outlet plug.
Insert probes all the way in.
Turn on TEST mode, wait 10 minutes for boiler to stabilize;
Take measurement.
Vent Gases
Test Port
Combustion Air Test
Port
A Pressure point upstream
B Pressure point downstream
C Modureg electrical connection
D Protection cap
E Minimum pressure adjustment
F Modureg
G Maximum pressure adjustment
I Gas valve electrical connection
N Compensation tube
9 - START UP PROCEDURE
Figure 17 - Test Ports
Figure 18 - Gas Valve
Table 11 - Combustion Table
Combustion Minimum/Maximum
Natural Gas
High Fire - CO
2
at 100 (%) 7.3 - 7.8
Low Fire - CO
2
at 33 (%) 3.0 - 5.0
N
C
D
B
A
D
N
C
E
G
F
I