Siemens LMV5 Quick Start Manual page 72

Cold Start (Thermal Shock Protection
All LMV5s with a load controller have a built in cold start function.
See Parameter Worksheet, Params & Display>Load Controller>Cold Start for specific details.
The cold start feature requires that the temperature or pressure of the boiler is measured by a
sensor connected to the LMV5, and that load control is being operated in Mode 2, 3 or 4.
For a hot water boiler (temperature based modulation) the same temperature sensor that is used
for modulation must be used for the cold start feature. For a steam boiler (pressure based
modulation) the pressure sensor used for modulation can also be used for cold start or an
additional temperature sensor can be added. Temperature sensors are generally recommended
since pressure does not always represent temperature in a steam boiler, especially when a steam
boiler is warming up. The paragraphs below will only mention temperature based cold start, but the
same ideas also apply to pressure based cold start.
The cold start feature can be set-up to warm the boiler in
1. Low - fire hold
The LMV5 will be held at low fire until the threshold off temperature is reached,
and then the LMV5 will be released to modulate.
This "hold" will re-engage when the temperature falls below the threshold on value.
ThresholdOn and ThresholdOff must be set to the desired temperatures.
StageLoad must be set to 0.
2. Temperature based stepping start
The LMV5 will be held at low fire until a certain temperature change is detected,
and then a step up in burner output (load) will be taken.
This will repeat until the threshold off temperature is reached.
ThresholdOn and ThresholdOFF must be set and StageLoad must be set to a value greater
than 0, since the step-up in load is determined by this parameter.
StageSetp_Mod must also be set to determine how much temperature change triggers a
step-up in load.
MaxTmeMod should be set to a high number (30 min) so that it has no effect.
3. Time based stepping start
The LMV5 will be held at low fire until a certain time elapses, and then a step-up in load will
be taken. This continues until the ThresholdOFF value is reached.
As the other two methods, ThresholdON, ThresholdOFF, and StageLoad must be set.
However, now StageSetp_Mod is set to a high number (80%) so that it has no effect and,
MaxTmeMod is set to determine how much time should elapse before the next load step is
triggered.
4. Temperature / Time based stepping start
This is similar to method 2, however,
now MaxTmeMod is set to have an effect (10 minutes for example).
When this is done, the maximum time that a step-up in load will take is 10 minutes,
regardless of the temperature change.
If the temperature change defined by StageSetp_Mod happens before the 10 minutes
elapses, then the temperature change will trigger the step-up in load.
When this mode is used, time usually triggers the load steps at the start of boiler warming
and temperature change usually triggers the load steps closer to the ThresholdOff
temperature. This is due to the more rapid rise in boiler temperature at higher firing rates.
LMV5 QSG Rev 4
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4
different ways:
Sec 4 Pg 16 www.scccombustion.com