6 MM Features
Mk8 MM Manual Page | 129
6.4 Continuous Pilot
The Mk8 MM has a continuous pilot (pilot relight – return to pilot) feature. If continuous pilot is enabled, when
the burner goes above its off differential of the required setpoint, the burner will continue to fire with only the
pilot valves energised.
To enable continuous pilot, set option/ parameter 111 to either 3 or 4 interrupted continuous pilot or
intermittent continuous pilot. If the burner goes off on high temperature/ pressure, then the pilot will continue
to fire for a time period, set in option 71. After the time set in option 71, if the main flame is not re-established
through load demand, the system will shut down and recycle. Option 72 sets the offset above the required
setpoint where during the time period, if the actual temperature/ pressure goes above this value, the pilot will
turn off as well.
In the situation when the burner switches back to pilot flame, the burner will open the pilot valves and after
the second safety time (option/parameter 116), the burner will close its main valves. During the hot standby
position, the gas pressure is checked by the gas sensor, it is important that the main valves and pilot valves
are connected with a small measuring pipeline. When burner is ready to go back to main flame the main fuel
valves will open and after the second safety time the pilot valves will be closed, and the normal operation will
start again.
When default settings are used, the quickest the MM can go from pilot to high fire once the stat comes on is
approximately 30 seconds. At the slowest motor travel speed and the maximum timings, it would take
approximately 1minute and 30 seconds to from pilot to high fire.
It is recommended that assured low fire shutoff (parameter 100) is used with continuous pilot.
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