Beckett CG4 - Manual (Page 22)

22
Section: START THE BURNER
Use Test Instruments to Set Combustion
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 flue pipe near the breech
(or upstream of the boiler breech damper, if
applicable) and in the front mounting plate area for
firebox pressure. Be careful not to damage any
water-backed surface.
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 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 stack or over-fire draft to the level
specified by the appliance manufacturer.
─ Natural Draft Applications; typically over-fire
draft is -0.01” or -0.02” W.C.
─ Direct Venting; typically may not require draft
adjustment.
─ High Efficiency/Positive Pressure Appliances;
(see manufacturer’s recommendations).
○ Oxygen – It is recommended that you measure the
oxygen (O
2
) early in the test sequence because high
levels of carbon monoxide can be created at very low
or even very high O
2
levels. The typical operating
range is between 3% – 5%.
○ Carbon monoxide (CO) – An operating range of 0
-50 PPM is recommended for the CG4 burner. The
maximum carbon monoxide (CO) level permitted in the
flue gas by the UL 795 Standard is 400 PPM (.04%).
○ Stack Temperature – The stack temperature must
be within the range specified by the appliance
manufacturer. Generally a 325°F stack temperature
is high enough to avoid corrosive condensation in
the vent system, however a large cross sectional
flow area chimney or a very tall chimney may require
a higher temperature. See ANSI Z 223.1/NFPA 54
for design requirements.
CO Leakage, Asphyxiation
Failure to maintain proper stack temperature could
result in flue gas condensing and cause chimney
damage which could result in CO leakage into
dwelling.
Recommended Combustion Adjustment
Procedure
1. Initiate a call for heat.
2. Adjust the draft or breech pressure to the appliance
manufacturer’s recommended level after flame has
stabilized. A breech pressure that does not exceed
-0.04 to -0.06”W.C. is generally acceptable.
3. Measure the carbon monoxide level and adjust air
settings, if necessary, to temporarily raise CO to
about 50 PPM for a test point.
4. Measure the O2 or CO2 at the 50 PPM CO level.
For this discussion, assume the O2 is 1.5% (11%
CO2).
5. 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.
6. Sample the CO level again. It should be in the 0 to
20 PPM range.
7. Check the draft to ensure it still meets
specifications. If a major change in draft is
required, repeat the above steps.
8. Check draft regulator for spillage. Confirm the
condition of the chimney if spillage is present.
9. Verify stack temperature meets appliance
manufacturer’s recommendations.
10. Perform any final adjustments and lock the air
settings securely. Run the burner through several
cycles to verify prompt ignition and stable burner
operation.
11. Record the combustion performance readings,
burner settings and appliance data on the start-up
form in the back of this manual and on the start-
up tag. If the burner is firing LP gas you must
also record set-up information on the propane
conversion label and attach it to the appliance.
12. Hang the start-up tag in a prominent, safe location
on or near the burner for future reference.