Installation Instructions

26 | Commissioning
SB625WS/SB745WS6 720 805 218 (2016/02)
6 Commissioning
6.1 Control unit settings
The purpose of optimum control unit settings is to achieve long burner
run times and avoid rapid temperature changes in the boiler. Gentle
temperature changes result in a longer service life of the heating system.
The control strategy of the control unit must therefore be prevented
from becoming ineffective, i.e. through the boiler water regulator
switching the burner on and off.
▶ Maintain the minimum differential between the selected shutdown
temperature of the high limit safety cut-out, the temperature
regulator, the maximum boiler water temperature and the maximum
temperature demand ( table 13).
▶ Select set temperatures for the heating circuits that are as low as
possible.
▶ Start heating circuits (e.g. when starting up in the mornings) at 5-
minute intervals.
Control unit settings
Fig. 25 Control unit settings
[1] High limit safety cut-out
[2] Temperature regulator
[3] MEC
▶ Select temperatures ( table 13, page 26) at high limit safety cut-
out [1] on the control unit and at temperature controller [2].
▶ Select the maximum boiler water temperature at the MEC [3].
NOTICE: Risk of boiler damage through contaminated
combustion air.
▶ Never operate the boiler in very dusty conditions,
e.g. if building work is taking place in the installation
room.
▶ Ensure adequate ventilation.
▶ Never use or store chlorinated cleaning agents or
halogenated hydrocarbons (as contained in spray
cans, solvents or cleaning agents, paints and
adhesives, for example) in the boiler room.
▶ A burner contaminated during building work must be
cleaned before commissioning.
▶ All cover plates, enclosures, clean out ports, and
guards must be in place at all times, except during
maintenance and servicing.
▶ Never burn garbage or paper in the unit, and never
leave combustible materials around it.
The boiler may be operated with a Buderus Logamatic
control unit from the 4000 series.
The maximum boiler water temperature can be selected
on the control unit (MEC) in the "Boiler parameters"
menu, under menu item "Max. shutdown temperature".
If the Buderus Logamatic 4000 control unit is used,
burner modulation in standard mode is not enabled for 3
minutes. Never modulate upwards more quickly than
this.
Recommended parameters (max.
temperature)
Logamatic 4321
High limit safetey cut-out (STB) 230 °F/110 °C min.5 K
Temperature regulator (TR) and
manual reset high limit.
210 °F/99 °C min. 6 K
Max. boiler water temperature 198 °F/92 °C min.7K
Max. temperature demand of
Heating Circuit or DHW
1
1. Both temperature demands must always be at least 7 K below the maximum
boiler water temperature.
185 °F/85 °C
Table 13 Adjustable parameters for Logamatic 4321
6 720 805 218-58.1T
21 3
The maximum temperature demand is not a value that is
directly selected. The maximum temperature demand is
composed of the set temperature and the rise.