A.O. Smith 3400, 2600, 1700, 2000 instruction manual High Fire Rate

HIGH FIRING RATE SETTING

Set the boiler to the high firing rate by setting the High Firing Rate RPM as described below. Check combustion readings using a combustion analyzer. If combustion readings are not in accordance with the chart below adjust the gas valve as follows: remove the flat, round, blue plastic cap from the cover. Using a 3 mm (7/64”) hex wrench, turn the adjustment screw counterclockwise to increase or clockwise to decrease gas flow and achieve the desired CO2 level. Refer to the Table 19 for correct settings. There will be a slight time delay between the adjustment and the response of the CO2 measuring instrument. Adjust the settings in small increments and allow the combustion readings to stabilize before readjusting. When desired adjustments are complete, reinstall the blue plastic cap on the cover. Combustion samples should be taken in the stack within two feet of the boiler. The carbon monoxide (CO) values in the combustion sample should not exceed 150 PPM under any circumstances. Contact OEM for any abnormal conditions leading to excessive CO above 150 PPM.

Table 19.  HIGH FIRE RATE

		RPM			CO2		*MANIFOLD PRESSURE
MODELS (XB/XW)	(APPROXIMATE FACTORY SET)						INCHES W.C
	NATURAL		PROPANE	NATURAL		PROPANE	NATURAL GAS	PROPANE
	GAS			GAS
1000 (920,000)	4450		4750	8.5 - 9.2%		9.3 - 10.2%	-3.5	-4.7
1300	4850		5100	8.5 - 9.2%		9.3 - 10.2%	-3.0	-3.6
1700	5700		5700	8.5 - 9.2%		9.3 - 10.2%	-3.6	-4.4
2000	4700		4750	8.5 - 9.2%		9.3 - 10.2%	-3.9	-4.9
2600	5700		5100	8.5 - 9.2%		9.3 - 10.2%	-3.3	-3.6
3400	5700		5700	8.5 - 9.2%		9.3 - 10.2%	-3.5	-4.4

LOW FIRING RATE SETTING

Set the boiler to the low firing rate by setting the Low Firing Rate RPM as described below. Check combustion readings using a combustion analyzer. If combustion readings are not in accordance with the chart shown below adjust as follows: remove the cap on the gas regulator using a slotted screwdriver. This will expose the offset adjustment screw. Using a TORX® T40 or a 5 mm hex wrench, carefully adjust the low fire gas setting to achieve the CO2 level prescribed in Table 20.

Note: The rotation of the Low Fire adjustment is opposite of the High Fire as follows: Clockwise rotation increases gas flow, counterclockwise rotation decreases gas flow.

Adjustments to the offset pressure regulators should not exceed 1/4 turn at a time before allowing the readings to respond and stabilize.

After proper low fire offset adjustment is made, reinstall the slotted cap on the regulator.

Following all gas valve adjustments, check for proper light-off and verify correct fuel/air mix and combustion quality throughout the entire firing range (from lowest to highest fan speed).

Note: Make sure the Manual Mode is set back to Automatic Mode to each of the burners, once the required settings are done. Turn off the individual burner before proceeding to the next burner settings.

Table 20.  LOW FIRE RATE

		RPM			CO2		*MANIFOLD PRESSURE
MODELS (XB/XW)	(APPROXIMATE FACTORY SET)						INCHES W.C
	NATURAL		PROPANE	NATURAL		PROPANE	NATURAL GAS	PROPANE
	GAS			GAS
1000 (920,000)	1650		1540	7.3 - 8.2%		8.4 - 8.8%	-0.3	-0.25
1300	1650		1600	7.3 - 8.2%		8.4 - 8.8%	-0.2	-0.14
1700	1700		1700	7.3 - 8.2%		8.4 - 8.8%	-0.2	-0.23
2000	1550		1540	7.3 - 8.2%		8.4 - 8.8%	-0.3	-0.31
2600	1700		1600	7.3 - 8.2%		8.4 - 8.8%	-0.2	-0.14
3400	1700		1700	7.3 - 8.2%		8.4 - 8.8%	-0.2	-0.23

*NOTE: Values listed in Table 19 and Table 20 are tested under laboratory conditions with minimum vent length. Values may slightly vary depending on ambient conditions and field equipment accuracy.

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