STIEBEL ELTRON SOM 7 SI - Manual (Page 23)

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SOM 7 SI
Display
Code
Parameter Name
and Reference
Recommended Setting and Explanation
(All temperatures in °F)
DT O
Switch on Temperature
Difference (p. 17)
15° Setting this too low can cause the circulator to cycle on and
off too frequently.
DT F
Switch off Temperature
Difference (p. 17)
5° Too high of a ΔT between DT O and DT F can cause the
circulator to switch on and off too frequently.
S MX
Maximum Store
Temperature (p. 17)
140° This will prevent the temperature at the top of the tank
from getting hot enough to cause the T & P valve to release.
This will also allow the cooling function to operate effectively.
EM
Collector Emergency
Shutdown Temperature
(p. 18)
310° This prevents the HX fluid directly behind that in the
sensor well from causing the system to go into emergency
shutdown mode as soon as the cooling function is activated.
OCX
System Cooling
Function (p. 18) On Failure to change this option to ‘on’ will likely result in
overheating of the system at some point.
CMX
Maximum Collector
Temperature (p. 18)
230° Having a relatively large ΔT between CMX and EM
prevents the HX fluid directly behind that in the sensor well
from causing the system to go into emergency shutdown mode
as soon as the cooling function is activated.
OCN
Minimum Collector
Temperature (p. 18)
Off The ΔT between DT O and DT F achieves the requisite
effect for most situations.
OCF
Antifreeze Option
(p. 18)
Off Unless the system is located in a region which rarely
experiences temperatures near freezing, and a very low glycol
to water percentage is being used.
OREC
Recooling Function
(p. 19)
On This prevents a cumulative overheating of the system by
ensuring a relatively high
Δt between the tank temperature and
and the security switch-off of the tank (205°).
O TC
Tube Collector
Function (p. 19)
Off Unless the system is utilizing tube collectors.
AH O
Thermostat Switch-On
Temperature (p. 20)
115 Or whatever temperature the user wants the boiler to
begin heating the tank water via the upper heat exchanger.
AH O
Thermostat Switch-Off
Temperature (p. 20)
125 Or whatever temperature the user wants the boiler to
stop heating the tank water via the upper heat exchanger.
t1 0-t3 F
Thermostat Switching
Times (p. 20)
00:00 Unless there are certain times in the day when the boiler
loop should not switch on.
OHQM
Energy Production
Measurement (p. 16)
Off Unless the installer has installed a sensor in position S4 and
wishes to utilize this function.
HND1
Solar Pump Operating
Mode (p. 20)
Auto This is the normal operating mode. The other two
modes are for testing, charging, etc.
HND2
Boiler Loop Operating
Mode (p. 20)
Auto This is the normal operating mode. The other two
modes are for testing, charging, etc.
LANG
Language (p. 20)
En (English) For most applications in North America this is
appropriate, with some exceptions.
4.2.2 Recommended Settings for Standard DHW System with Boiler Backup (Arr. 3)