750-382
CBT
4-25
On/off boilers
The OLC and HLC can be tested while the boiler is producing steam by adjusting the switch setting downward.
A lockout should result when the switch setting is at or just below the current steam pressure.
Readjust each switch (and reset HLC) after testing.
4.2 — On/off boilers
Follow steps 4.1.1 through 4.1.4 above to prepare for startup.
4.2.1 — Ignition adjustment
Normal setting is 0.5" W.C. when the burner is on. The flame must be sufficient to be proven by the flame detec-
tor and ignite the main flame.
Although it is possible to visually adjust the size of the minimum flame, the recommended method is to obtain a
proper DC volt or microamp reading of the flame signal. Refer to burner control instructions for optimal flame sig-
nal readings.
4.2.2 — Gas Adjustments
Low fire combustion analysis typically is 7% to 9% O2 and less than .04% CO (400 ppm). A high fire reading
typically is 3% to 4% O2 and less than .04% CO.
4.2.3 — Electrical interference test
Prior to putting the burner into service, conduct the following test to ascertain that main power will not cause the
flame relay to pull in.
1. Close the manual gas valves.
2. Start the burner, the flame relay should not pull in (be energized).
3. Upon completion of successful test, proceed with startup procedures.
4. Reconnect the power supply and proceed with startup procedures.
4.3 — Boil-out of a new unit
The inside of a new boiler may contain oil, grease, or other contaminants which, if not removed, could adversely
affect system performance. New units should be cleaned by boil-out before use.
Recommended boil-out procedure is as follows:
1. Determine boiler water capacity (see Table 4-4). Have sufficient cleaning material on hand to complete the
job.
2. When dissolving dry chemicals, slowly introduce the chemical into warm water in a suitable container. Stir
constantly until the chemical is completely dissolved.
3. An over-flow pipe should be attached to one of the top boiler openings and routed to a safe point of
discharge. A relief or safety valve tapping is normally used for this purpose.
4. Water relief valves and steam safety valves must be removed before adding the boilout solution to avoid
contaminating the valves. Use caution when removing and reinstalling these devices.
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