5-11
TROUBLESHOOTING
TANKLESS WATER HEATER 199
5.4.2 Domestic hot water does not reach the correct temperature
POSSIBLE CAUSES
ANALYSIS
POSSIBLE SOLUTION
Domestic hot water flow is too high.
→ Yes
↓No
Reduce the domestic hot water flow.
Setting for domestic hot water
temperature is too low.
→ Yes
↓No
Increase the domestic hot water temperature.
Insufficient heat transfer due to calcium or
contamination in the domestic hot water-sided
central heating unit.
→ Yes
↓No
De-calcify or flush the domestic hot water-sided central
heating unit.
The flue is blocked.
→ Yes
Check the flue.
5.4.3 Burner ignites loudly
POSSIBLE CAUSES
ANALYSIS
SOLUTION
Inlet pressure is too high.
→ Yes
↓No
The gas pressure regulator may be defective. In that case,
contact the energy company.
Ignition distance is incorrect.
→ Yes
↓No
Replace the ignitor including the ignition cable.
Gas-air control is not correctly
adjusted.
→ Yes
Check and/or adjust combustion with a calibrated
combustion analyzer.
5.4.4 Burner resonates
POSSIBLE CAUSES
ANALYSIS
SOLUTION
Gas inlet pressure lower than 4“ w.c.
or sometimes disappears.
→ Yes
↓No
The gas pressure regulator may be defective. Contact the
energy company.
There is recirculation of flue gases.
→ Yes
↓No
Check the flue and air supply duct.
Gas-air control is not correctly adjusted.
→ Yes
↓No
Check and/or adjust combustion with a calibrated
combustion analyzer.
Burner seal is defective.
→ Yes
↓No
Replace the burner seal.
Burner is defective.
→ Yes
Replace the burner.