IGNITION POINT Default - 1%, Stage Settings

- STAGE SETTINGS - Mode

>Ignition % Mod Start %

----- STAGE ------

IGNITION POINT

Value -> New Value

----- STAGE ------

IGNITION POINT

Value -> New Value

- STAGE	SETTINGS -
Mode	%
Ignition
>Mod Start %

----- STAGE		------
MODULATION START
Value ->	New Value


----- STAGE		------
MODULATION START
Value ->	New Value

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IGNITION POINT Default - 1%

When Can a Stage Begin Modulating?

•The Ignition Point is the percent modulation which must be attained before the unit can be activated.

•For most boilers, the Ignition Point should be set at 1%.

•Older units or atmospheric units may require the modulating fuel valve to be open from 20-50% before proper ignition can be attained. Check with the boiler manufacturer if you are in doubt about the minimum position of the fuel valve for ignition.

MODULATION START Default - 75%

When Does the Next Stage Turn On?

•The Modulation Start determines at what percent modulation of the current Stage the next Stage in the sequence will be activated.

•For example, if the Modulation Start for Stage A is set to 75%, then when Stage A reaches 75% modulation, Stage B (if Stage B is in Auto Mode and is not already on) will be brought on in low fire.

•When modulation is decreasing, the lag unit will remain on in low modulation, until the previous stage reaches 40% of its Modulation Start point, or 2% above the Ignition Point, whichever is higher.

•Using the same example, as the load decreased, Stage B would modulate down to low. Stage A would then modulate down to 30%. Only then would Stage B turn off.

•If the Lag Delay (see pg. 18) is set to anything other than 0, a Stage must always go up to 100% modulation before the next stage is activated. However, the Modulation Start should still be set correctly, because it will be valid when modulation is decreasing.

•The Modulation Start point will generally be set differently based on the Modulating Mode selected (see pg. 12).

STAGE SETTINGS

When does the lag stage turn OFF?

At 40% of the Previous Stage Mod Point Or 2% Above the Ignition Point (Whichever is higher)

Example:

Stage A - Lead

Ignition Point - 1%

Mod Start 75%

When does Stage B turn OFF? At 40% of Stage A's Mod Point

75 x (40/100) = 30

Stage B will turn off when A's modulation reaches 30%

Modulating Mode - NORMAL

•Lower settings of the modulation start point allow the next boiler in the sequence to be activated and warmed up, generally allowing more even set point control.

•Higher settings of the modulation start point prevent unnecessary Stages from being activated. Also, as most units run more effi- ciently at higher modulation, a higher setting can result in fuel savings.

•Some general guidelines follow:

-Less than 50% - not recommended in the Normal mode.

-50%-70% - These lower settings might be used in an application which has wide load swings such as an industrial plant or a hospital. This allows an additional boiler to be brought on line before the previous boiler has begun to reach its capacity. The next boiler will now be available for fast, high demands.

-70-90% - This range is recommended for most applications. When there are several Stages of relatively equal capacity and all can be used to hold the load, this allows some degree of overlap, without activating unnecessary Stages.

-90-100% - Recommended when one Stage can almost always handle the load, and other Stages are mainly for backup.