Beckett RWF40 CG15 Manuel D’Utilisation

CG15, CG25, CG50 Burner Manual

High gas pressure switch – With the burner fi ring 
and a manometer attached to the test port nearest 
the high pressure switch, gradually increase the 
gas pressure until the high pressure switch opens 
and shuts the burner off. Note the pressure and 
manually reset the switch. The high gas pressure 
switch should be set at one and one half times the 
high fi re manifold pressure (see nameplate data in 
Figure 1 or set switch as determined by testing).
Leak-test valve – With the burner fi ring and 
manometer attached to the leak-test valve port, turn 
the burner electrical switch off and observe that 
the gas pressure does not increase after several 
minutes. This proves total closure of the main gas 
valve.
Flame safeguard safety lockout – Simulate a 
fl ame failure by turning the main gas supply off. The 
control should shut the burner off on safety within 
the safety lockout time.  
Flame sensor circuit (fl ame rod) – With the 
burner power switch turned off, refer to the wiring 
diagram supplied with the control and locate the 
sensor connection terminals. Place DC voltmeter 
probes in the fl ame amplifi er test jacks.  With the 
burner fi ring, the fl ame signal should be steady and 
at least 1.25 VDC.
Flame sensor circuit (UV scanner) – With the 
burner power switch turned off, refer to the wiring 
diagram supplied with the control and locate the 
sensor connection terminals. Place DC voltmeter 
probes in the fl ame amplifi er test jacks.  With the 
burner fi ring, the fl ame signal should be steady and 
at least 1.25 VDC.

Verify that all boiler sections, canopy, and access plates 
or doors are fully equipped with gaskets and sealed 
against any leakage, which could affect the combustion 
test results.  Before making these tests, operate the 
burner for several minutes to allow the heating system 
temperature to stabilize or nearly reach steady-state 
levels.  Record all results in the start-up log for future 
reference.

Draft – Set the breech or furnace pressure to the 
level specifi ed by the appliance manufacturer.  Typical 
example: +0.10” W. C.

Oxygen – For both low fi re and high fi re it is 

recommended that you measure the oxygen (O2) early 

in the test sequence because high levels of carbon 

monoxide can be created at very low or even very high 

O2 levels.  The typical operating range is between 2.5% 

– 4.5 %.  The equivalent carbon dioxide (CO2) operating 

range is 9% – 10.5%.  

High excess air levels reduce the 

fl ame’s UV output and the scanner 

signal that proves the burner is fi ring.

Carbon monoxide (CO) – An operating range of 0 -50 

PPM is recommended for the burner. The maximum 

carbon monoxide (CO) level permitted in the fl ue gas by 

the UL 795 Standard is 400 PPM (0.04%).  

Stack Temperature – The stack temperature should be 

within the range specifi ed by the appliance manufacturer.  

It is infl uenced by input fi ring rate, fl ame shape, excess 

air ratio, and cleanliness of boiler fl ue passages.  This 

temperature, combined with the ambient temperature, 

and O2% (or CO2) is used in calculating the appliance 

effi ciency. 

Adjust the draft or breech pressure to the appliance 
manufacturer’s recommended level.
Measure the carbon monoxide level and adjust 
air settings, if necessary, to regulate it to about 50 
PPM for a starting point.  
Measure the O2 or CO2 at the 50 PPM CO level.  

For this discussion, assume the O2 is 1.5% (11% 

CO2).
Open the air adjustment until the O2 level is 

increased by at least 1% or to 3% O2  (whichever 

is higher).  This should reduce the CO level and 
provide a margin of reserve air to accommodate 
variable conditions.
Sample the CO level again.  It should be in the 0 to 
20 PPM range.
Check the draft to ensure it still meets 
specifi cations.  If a major change in draft is 
required, repeat the above steps.
Perform any fi nal adjustments and lock the air 
settings securely. Run the burner through several 
cycles to verify prompt ignition and stable burner 
operation.

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7.

Always use calibrated test 
instruments to set combustion 

levels. Verify that test instruments are calibrated and 
in good working condition.  If not already provided, drill 
test access holes in the fl ue pipe near the breech (or 
upstream of the boiler breech damper, if applicable) and 
in the front mounting plate area for fi rebox pressure.  Be 
careful not to damage any water-backed surface.