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5.4.3 Central heating system remains too warm
POSSIBLE CAUSES
Room thermostat / weather-dependent
control is defective or has
a short circuit.
There is thermo-siphon in the central
heating circuit.
5.4.4 No domestic hot water (DHW)
POSSIBLE CAUSES
The power LED is not shown.
Flow sensor does not work.
Domestic hot water flow < 0.5 gpm
Domestic hot water sensor S3 is
defective.
No electricity on the flow sensor (5V
DC).
5.4.5 Domestic hot tap water does not reach the correct temperature
POSSIBLE CAUSES
Domestic hot water flow is too high.
Setting for domestic hot water
temperature is too low.
Insufficient heat transfer due to calcium or
contamination in the domestic hot water-sided
central heating unit.
The central heating system becomes
warm while tapping water.
TROUBLESHOOTING
SFC BOILER / WATER HEATERS - SFC 199
ANALYSIS
→ Yes
↓No
→ Yes
ANALYSIS
→ Yes
↓No
→ Yes
↓No
→ Yes
↓No
→ Yes
↓No
→ Yes
ANALYSIS
POSSIBLE SOLUTION
→ Yes
Reduce the domestic hot water flow.
↓No
→ Yes
Increase the domestic hot water temperature.
↓No
→ Yes
De-calcify or flush the domestic hot water-sided central
heating unit.
↓No
→ Yes
Undesirable circulation during domestic hot water demand
in the central heating circuit due to thermo-siphon of the
second pump in the central heating circuit. Place a check
↓No
valve (in the case of thermo-siphon) or a two-way valve (if
there is a second pump).
POSSIBLE SOLUTION
•
Check the wiring.
Check the OpenTherm, On/Off connection of the unit, or
room thermostat. Replace the thermostat.
•
Replace the weather-dependent control.
Place a check valve (in the case of thermo-siphon) or a
two-way valve (if there is a second pump in the central
heating circuit).
POSSIBLE SOLUTION
•
Check the power supply.
•
Check the fuse (see electrical schematic).
Replace the flow sensor.
Increase the domestic hot water flow.
Replace the domestic hot water sensor S3.
Check the wiring according to the schematic.
WIRING ACCORDING TO THE SCHEMATIC.
CK THE
5-9
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