Unigas HTP90A, Manual Of Installation - Use - Maintenance

Page: 52 / 84

52
TROUBLESHOOTNG GUIDE - Gas operation
BURNER DOESN'T LIGHT
* No electric power supply * Wait until power supply is back
* Main switch open * Close the switch
* Thermostats open * Check set points and thermostat connections
* Bad thermostat set point or broken thermostat * Set or replace the thermostat
* No gas pressure * Restore gas pressure
* Safety devices (manually operated safety
thermostat or pressure switch and so on) open * Restore safety devices; wait that boiler reaches its temperature
then check safety device functionality.
* Broken fuses * Replace fuses. Check current absorption
* Fan thermal contacts open (only three phases) * Reset contacts and check current absorption
* Burner control locked out * Reset and check its functionality
* Burner control damaged * Replace burner control
GAS LEAKAGE: BURNER LOCKS OUT (NO FLAME)
* Gas flow too low
* Increase the gas flow
* Check gas filter cleanness
* Check butterfly valve opening when burner is starting (only
Hi-Low flame and progressive)
* Ignition electrodes discharge to ground because
dirty or broken
* Clean or replace electrodes
* Bad electrodes setting * Check electrodes position referring to instruction manual
* Electrical ignition cables damaged * Replace cables
* Bad position of cables in the ignition transformer
or into the electrodes
* Improve the installation
* Ignition transformer damaged * Replace the transformer
BURNER LOCKS OUT WITH FLAME PRESENCE
* Bad flame detector set
* Flame detector damaged
* Replace or adjust flame detector
* Bad cables of flame detector * Check cables
* Burner control damaged * Replace burner control
* Phase and neutral inverted * Adjust connections
* Ground missing or damaged * Check ground continuity
* Voltage on neutral
* Take off tension on neutral
* Too small flame (due to not much gas)
* Adjust gas flow
* Check gas filter cleanness
* Too much combustion air * Adjust air flow rate
BURNER CONTINUES TO PERFORM PRE-PURGE
* Burner control damaged * Replace burner control
* Air servomotor damaged * Replace servomotor
BURNER CONTINUES TO PERFORM ALL ITS FEA-
TURES WITHOUT IGNITING THE BURNER
* Air pressure switch damaged or bad links * Check air pressure switch functions and links
* Burner control damaged * Replace burner control
BURNER LOCKS OUT WITHOUT ANY GAS FLOW
* Gas valves don’t open
* Check voltage on valves; if necessary replace valve or the
burner control
* Check if the gas pressure is so high that the valve cannot open
* Gas valves completely closed * Open valves
* Pressure governor too closed * Adjust the pressure governor
* Butterfly valve too closed * Open the butterfly valve
* Maximum pressure switch (if installed ) open. * Check connection and functionality
* Air pressure switch doesn’t close the NO contact * Check connections
* Check pressure switch functionality
BURNER LOCKS OUT AND THE CONTROL WIN-
DOW SHOWS A P (SIEMENS & STAEFA ONLY)
* Air pressure switch damaged (it keeps the
stand-by position or badly set
* Check air pressure switch functionality
* Reset air pressure switch
* Air pressure switch connections wrong * Check connections
* Air fan damaged * Replace motor
* No power supply * Reset power supply
* Air damper too closed * Adjust air damper position
BURNER LOCKS OUT DURING NORMAL RUNNING
* Flame detector circuit interrupted
* Check wiring
* Check photocell
* Burner control damaged * Replace burner control
* Maximum gas pressure switch damaged or
badly set
* Reset pressure switch or replace it
WHEN STARTING THE BURNER OPENS FOR A
WHILE THE VALVES AND THEN REPEATS FROM
THE BEGINNINGTHE CYCLE FROM PRE-PURGE
* Gas pressure switch badly set * Reset the pressure switch
* Gas filter dirty * Clean gas filter
* Gas governor too low or damaged * Reset or replace the governor
BURNER STANDS WHILE RUNNING WITHOUT ANY
SWITCHING OF THERMOSTATS
* Thermal contacts of fan motor open
* Reset contacts and check values
* Check current absorption
FAN MOTOR DOESN'T START
* Internal motor wiring broken * Replace wiring or complete motor
* Fan motor starter broken * Replace starter
* Fuses broken (three phases only) * Replace fuses and check current absorption
BURNER DOESN'T SWITCH TO HIGH FLAME
* Hi-low flame thermostat badly set or damaged * Reset or replace thermostat
* Servomotor cam badly set * Reset servomotor cam
SOMETIMES THE SERVOMOTOR RUNS IN THE
WRONG WAY
* Servomotor capacitor damaged * Replace capacitor