6 MM Features
Mk8 MM Manual Page | 123
6 MM FEATURES
6.1 Firing Rate Control
6.1.1 Hand Operation
Hand operation enables the firing rate positions to be set to a specific position, in the range of low to high
fire, when the burner is firing. Fuel flow metering must be entered. IBS sequencing will not operate correctly
if the MM is in hand mode. Hand mode can only be activated when the burner is firing.
The Mk8 MM will go into hand mode when a voltage is detected on Terminal 94 or when the hand mode
button is pressed in the Status screen. Arrows will then appear on the screen which can be used
to increase and decrease the firing rate. Once the hand mode is deactivated, the MM will go to auto mode
and fire according to normal modulation.
If Hand and Low Flame Hold are selected at the same time via Terminals 94 and 95, then Low Flame Hold
takes priority.
6.1.2 Low Flame Hold
Low flame hold is the state when the MM’s firing rate goes to its low fire position, while the burner is firing.
Fuel flow metering must be entered. Sequencing will not operate correctly if the MM is in low flame hold.
Low Flame Hold can be selected on the Mk8 MM by introducing live input on terminal 95 or by pressing the
Low Flame Hold soft button from the MM status screen. The low fire position will be maintained
until the input on terminal 95 is removed or the button is pressed again. When switching from low flame hold
to auto the MM will return to normal modulation.
6.1.3 Auto Operation
The MM ‘Auto’ operation enables the burner modulation to maintain the setpoint; the firing rate will modulate
according to how far away the actual temperature or pressure is away from the required setpoint. The firing
rate is determined from the fuel flow metering entered via option 57; the more accurate the fuel flow
metering, the more accurate the firing rate.
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