2 Flame Safeguard
Page | 57
MM Application Possibilities
2.6
No Pre-Purge
It is possible to minimise the burner start-up time by bypassing the pre-purge. The major advantage of
this control means that the overall boiler efficiency is increased by minimising the heat loss to the
stack during a purge cycle. This means the burner starts-up quicker therefore reaching setpoint in a
reduced time. According to the EN676 European regulation, the burner is allowed to restart without a
pre-purge if the burner has recycled due to operational temperature/pressure. When the burner is
stopped by a lockout then this procedure is not allowed and the burner will have to start-up as normal
with a pre-purge. In order for no pre-purge to be active, valve proving must take place and finish
successfully. If this valve proving operation is successful then the burner may start-up without a pre-
purge.
In order to initiate the no pre-purge feature, option/ parameter 143 must be set to a value of 1. During
the first start-up the burner will start with a pre-purge initiated. Once the complete commissioning
curve has been entered and the burner has started successfully, the burner will then start-up every
time with no pre-purge. If the burner goes above its setpoint and turns off on high temperature/
pressure, then the next time the burner starts-up, it will go through the VPS operation and then light
off without a pre-purge, i.e. the burner has shut down in a controlled manner and the gas valves have
been checked for integrity.
According to the EN676 regulation, the burner is only allowed to work in this manner if VPS operation
has been set to operate before the burner starts up; option/parameter 129 must be set to 0.
The start sequence without pre-purge is as follows:
1. Firstly the system goes through its internal tests and relay checks.
2. Call for heat on Terminal 57 activates and the system will go through the VPS operation.
3. If this operation is successful then the MM will drive the channels to the light off or start
position.
4. Once all channels reach the start position then the burner will light off.
burner shuts down in an abrupt manner, e.g. loss of power to the unit, then the next time the burner
starts-up a complete purge will be initiated.
If no pre-purge is enabled in option/parameter 143, and one or more of the following conditions occur,
the next time the burner starts up, a complete pre-purge will be initiated:
•
Burner lockout
•
Loss of power to the MM
•
VPS checks have failed
•
MM has been in standby for 24 hours or more
Note:
Pre-purge is only available on fuels which are optioned as gaseous.
Summary of Contents for Mk8 MM
Page 1: ...Combustion Management Systems MM APPLICATION POSSIBILITIES Technical Manual 18 12 2019...
Page 8: ...1 Sensors Page 2 MM Application Possibilities Gas Pressure Sensor...
Page 27: ...1 Sensors Page 21 MM Application Possibilities Air Pressure Sensor...
Page 32: ...1 Sensors Page 26 MM Application Possibilities Steam Pressure Sensor...
Page 36: ...1 Sensors Page 30 MM Application Possibilities Outside Temperature Sensor...
Page 37: ...1 Sensors Page 31 MM Application Possibilities Outside Temperature Module...
Page 38: ...1 Sensors Page 32 MM Application Possibilities Outside Temperature Module Wiring...
Page 42: ...2 Flame Safeguard Page 36 MM Application Possibilities 2 1 1 Interrupted Pilot Gas...
Page 43: ...2 Flame Safeguard Page 37 MM Application Possibilities 2 1 2 Interrupted Pilot Oil...
Page 46: ...2 Flame Safeguard Page 40 MM Application Possibilities IR End View Scanner...
Page 72: ...2 Flame Safeguard Page 66 MM Application Possibilities 2 9 3 Wiring...
Page 81: ...5 Intelligent Boiler Sequencing Page 75 MM Application Possibilities 5 1 3 Hot Water Example...
Page 83: ...5 Intelligent Boiler Sequencing Page 77 MM Application Possibilities 5 1 5 IBS Communications...
