Beckett CF800, CF500 manual Sequence of operation typical, ‰ Set combustion using instruments

‰Set combustion using instruments

1.Allow the burner to run for approximately 5 to 10 min- utes.

2.Set the stack or over-fire draft to the level specified by the appliance manufacturer.

yNatural Draft Applications; typically over-fire draft is -0.01” or -0.02” w.c.

yDirect Venting; typically may not require draft adjust- ment.

yHigh Efficiency/Positive Pressure Appliances; also vary from traditional appliances (see manufacturer’s recommendations).

3.Follow these four steps to properly adjust the burner:

Step 1: Adjust the air shutter/band until a trace of smoke is achieved.

Step 2: At the trace of smoke level, measure the CO2 (or O2) . This is the vital reference point for further adjustments. Example: 13.5% CO2 (2.6% O2)

Step 3: Increase the air to reduce the CO2 by 1.5 to 2 percentage points. (O2 will be increased by approxi- mately 2.0 to 2.7 percentage points.) Example: Re- duce CO2 from 13.5% to 11.5% (2.6% to 5.3% O2).

Step 4: Recheck smoke level. It should be Zero.

yThis procedure provides a margin of reserve air to accommodate variable conditions.

yIf the draft level has changed, recheck the smoke and CO2 levels and readjust the burner, if necessary

4.Once combustion is set, tighten all fasteners on air band, air shutter and escutcheon plate.

5.Start and stop the burner several times to ensure satis- factory operation. Test the primary control and all other appliance safety controls to verify that they function ac- cording to the manufacturer’s specifications.

6.Check the breech draft pressure against the appliance manufacturer’s recommended setting (typically + 0.1” W.C.). If the breech pressure is higher or lower than rec- ommended level, adjust the appliance breech damper to achieve the specified setting. Recheck the smoke and CO2 levels. Adjust burner air if necessary.

Sequence of operation — typical

1.Standby — The burner is idle, waiting for a call for

heat. When a call for heat is initiated, there is a 3- to 10-second delay while the control performs a safe start check.

2.Valve-on delay — As applicable, the ignition and mo- tor are turned on for a 15-second prepurge.

3.Trial for ignition (TFI) — The fuel valve is opened, as applicable. A flame should be established within the 15- second lockout time (30-second lockout time is avail- able).

4.Lockout — If flame is not sensed by the end of the TFI, the control shuts down on safety lockout and must be manually reset. If the control locks out three times in a row, the control enters restricted lockout. Call a quali- fied service technician.

5.Ignition carryover — Once flame is established, the ignition remains on for 10 seconds to ensure flame sta- bility. It then turns off.

6.Run — The burner runs until the call for heat is satis- fied. The burner is then sent to burner motor-off delay, as applicable, or it is shut down and sent to standby.

7.Recycle — If the flame is lost while the burner is firing, the control shuts down the burner, enters a 60-second recycle delay, and then repeats the ignition steps out- lined above. If the flame is lost three times in a row, the control locks out to prevent continuous cycling with repetitious flame loss caused by poor combustion.

8.Burner motor-off delay — If applicable, the fuel valve is closed and the burner motor is kept on for the selected postpurge time before the control returns the burner to standby.

Figure 10. - Typical sequence of operation

1

			Standby
2	Valve-on	3	Trial for	4
				Lockout
	delay		ignition
		5	Ignition
			carryover
8	Motor-off	6		7
	delay		Run	Recycle
	(postpurge)

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