TG, TH DGH - FC7 & 11
This information is to assist with diagnosis of FC7 & 11 on TG and TH products manufactured 2006-2015
• FC7 = The BSC has detected that the EFS (Fenwal) has failed to establish flame after 3 ignition attempts
FC7 – Failure to establish flame after 3 ignition attempts
Check heater operation to determine if fault code 7 has been caused by anything obvious that prevents it cross igniting and detecting flame at the flame sense electrode.
OT3 open (located on burner cover)
• Check switch – if open, reset button will click when pressed
No power to gas valve – Possible Fenwal failure
• Check voltage to gas valve on-off coil – 24Vac during ignition
• Check voltage between Fenwal V1 & earth – 24Vac during ignition
Ignition cable damaged or disconnected
• Check ignition lead- reconnect or replace if required
Sensor cable damaged or disconnected
• Check sensor lead – reconnect or replace if required
Incorrect spark gap
• Check spark gap between ignition electrode and burner face – adjust to 3-4mm if required
Incorrect gas supply pressure to heater
• Check supply pressure at inlet pressure tapping on gas valve with heater on maximum and all other gas appliances running
NG – minimum 1.13 kPa
Propane – minimum 2.75 kPa
• Check gas meter regulator outlet pressure and fitting line size and length
Incorrect test point/burner pressure
• Check pressure at outlet/burner pressure test point on gas valve with heater on maximum and all other gas appliances running – compare with value specified on data label
NB: All natural gas models: 875 +/- 50 Pa
Gas supply turned off at gas meter, heater isolation valve or gas valve on/off switch
• Check gas supply – turn on if required
Incomplete cross-ignition
• Check flames travel freely across all burners at ignition
• Check cross lighting slots on burners for obstructions – clean/clear or replace if required
• Check for dirty/blocked injectors – clean/clear or replace if required
Power supply polarity reversed
• Check active/neutral polarity – correct if required. Check correct connection of active/neutral and earth – correct if required.
FC7 intermittent and FC11 (loss of flame signal) in fault log history
• IMPORTANT: - FC11 is only displayed if the EFS (Fenwal) fail to energise the gas valve during flame establishment period. If the flame is lost during run mode FC11 is not seen on the screen and is recorded only in the Fault log history
If heater ignites when you attend but has FC7 and FC11 in its fault log history it means it may at times sense flame and operate – Therefore, most important is to check signal strength.
Check signal strength with a multi meter set to DC voltage
Start heater and when flame cross ignites and is present at the flame sense electrode, measure DC voltage across metal terminals FC- and FC+ on the EFS (Fenwal). A reading of 1.5 to 2 Volt DC is considered good signal strength. Any values below 1 Volt DC need to be investigated and rectified.
Flame signal lost due to permanent or intermittent fault with flame sense lead or electrode
• Check flame sense lead is connected securely
• Check flame sense lead is not damaged or shorted – replace if required.
• Check flame sense gap – should be 4-6mm from flame sense electrode to burner face
• Check ignitor and sensor for defects - – sometimes the porcelain may have a slight crack that isn’t visible to the eye – replace if unsure
• Check flame sense electrode is clean – clean with a non-metallic abrasive cloth (for example a Scotch bite pad or similar) – replace if unsure
