Baxi Luna HT Residential series User manual

EnErgy-EfficiEnt,
EnvironmEntally-friEndly
HEating SolutionS
Baxi Luna HT
Residential
Troubleshooting
Guide

Baxi Luna HT Troubleshooting Guide
1
WARNING!
THIS DOCUMENT IS INTENDED ONLY AS AN EDUCATIONAL TOOL
THIS TROUBLESHOOTING GUIDE, ND THE INSTRUCTIONS ND SUGGESTIONS
WITHIN RE INTENDED SOLELY S N EDUC TION L TOOL SSISTING
COMPLETELY QU LIFIED G S PPLI NCE MECH NICS WHO H VE SUCCESSFULLY
COMPLETED THE B XI INST LL TION PROGR M. USE OF THE INFORM TION
HEREIN FOR THE PURPOSES OF ONSITE PPLI NCE CORRECTION BY
UNTR INED PERSONNEL M Y C USE EXTREMELY D NGEROUS CONDITIONS,
ND M Y VOID THE M NUF CTURER’S W RR NTY. BAXI N.A. SSUMES
BSOLUTELY NO LI BILITY IN THE EXECUTION OF THE TR INING
SUGGESTIONS IN THIS DOCUMENT. SHOULD YOU EXPERIENCE PROBLEMS
OR COMPLIC TIONS BEYOND YOUR RE LM OF TR INING, PLE SE
CONT CT BAXI N.A. FOR FURTHER INSTRUCTIONS.

Baxi Luna HT Troubleshooting Guide
2
RESETTING UNIT
IF A FAULT OCCURS, THE DISPLAY READS OUT AN ERROR MESSAGE IDENTIFYING IT. NOTE: IF THE
ERROR MESSAGE CONTAINS MORE THAN TWO DIGITS (E.G. E133), THE DISPLAY READS OUT THE FIRST
TWO DIGITS “E1”FOLLOWED BY THE LAST TWO DIGITS “33”.
IF AN ERROR CODE APPEARS YOU WILL NEED TO RESET THE BOILER USING THE TOGGLE SWITCH ON THE
LEFT HAND SIDE OF THE CONTROL PANEL. TURN THE TOGGLE SWITCH TO THE “R” POSITION (RESET)
FOR THREE SECONDS (FIG. 2.3) AND THEN LET GO. THE TOGGLE SWITCH SHOULD GO TO THE WINTER
MODE POSITION (FIG. 2.1) AND ATTEMPT IT’S SEQUENCE OF OPERATION PROVIDING THERE IS A CALL
FOR HEAT OR DOMESTIC HOT WATER.

Baxi Luna HT Troubleshooting Guide
3
Baxi Luna HT Troubleshooting Guide
Note: It is recommended that a combustion analyzer test be performed at every visit and that the proper adjustments are made if
necessary.
Error
Code Description Solution
E10 Outdoor Temperature
Sensor fault
1- Disconnect the outdoor temperature sensor and take an ohm reading using chart B.
If the sensor is out of calibration replace it.
2- If the Sensor is working properly replace the main control board.
NOTES:
E20 CH NTC Sensor Fault
1- Take an ohm reading of the CH NTC sensor using chart . If the sensor is out of
calibration, replace the sensor. If the sensor is working properly, replace the main
control board.
Note: The CH NTC sensor sits in a dry well and should always be covered in heat transfer
paste.
NOTES:
E50 DHW NTC Sensor Fault
1- Take an ohm reading of the DHW NTC sensor. If the NTC sensor is out of calibration
replace the faulty sensor.
2- Check for a resistance in terminals 9 and 10 on the M2 connector (Only for heating
boilers)
3- If utilizing an indirect tank sensor, take an ohm reading using chart C. If the sensor
is faulty replace it. If the sensor is working check parameter 651 on the Q 73. (For
heating only models)
4- If problem persists replace the main control board
Note: The DHW NTC sensor is in a wet well, shutoff the cold water inlet and open a hot
water tap before replacing the sensor.
NOTES:
E110 High Limit Temperature
Sensor Activating
1- Check pump to make sure it is running and not ceased.
2- Check for restrictions
3- Make sure that all air is purged from the system
4- Take an ohm reading on the high limit sensor (0Ω indicates the sensor is closed, OL
indicates the sensor is open)
5- If an E110 error code persists change the high limit sensor.
NOTES:

Baxi Luna HT Troubleshooting Guide
4
E119 Low Water Cut off Pressure
Switch Activating
1- Ensure all air is purged from the system and all shutoff valves are open
2- Check boiler and system for leaks
3- Ensure the pressure in the expansion tank is 11.6 psi
4- Fill the system between 1 and 1.5 bar on the pressure gauge.
5- If an E119 error code persists jump the leads on the low water cutoff. If the boiler
fires up change the low water cutoff switch.
NOTES:
E130 Flue Gas Temperature
Sensor/ Air Pressure Switch
If unit can be reset (Pressure Switch ctivated)
1- Check for obstructions in the venting and termination
2- Ensure the venting is within the maximum venting length requirements
3- Make sure there is water in the condensate trap
4- Check that the proper Q 73 parameter values have been adjusted with respect to
gas type, venting length and altitude. Refer to installation manual for values
5- Check the silicone tubes coming from the air pressure switch for kinks, melting and
holes, make sure that the low pressure opening at the back of the unit is not
blocked.
6- Ensure that there are no loose wires and that the pressure switch is opening and
closing properly
7- Reset boiler and analyze the combustion gas to ensure the correct CO2 and CO
values. Refer to the installation guide for combustion specifications.
Note: When CO levels are significantly higher than the numbers above the boiler’s
specifications it is recycling products of combustion. Check all gasket seals between the flue
and air intake venting connections.
If unit cannot be reset (Flue High Limit has ctivated)
1- The flue high limit has a red manual reset button in the center of the sensor.
2- Check for obstructions in the venting and termination
3- Ensure the venting is within the maximum venting length requirements
4- Check that the proper Q 73 parameter values have been adjusted with respect to
gas type, venting length and altitude. Refer to installation manual for values
5- Reset boiler and analyze the combustion gas to ensure the correct CO2 and CO
values. Refer to the installation guide for combustion specifications.
Note: When CO levels are significantly higher than the numbers above the boiler’s
specifications it is recycling products of combustion. Check all gasket seals between the flue
and air intake venting connections.
NOTES:
E133 Burner Lockout
No Spark:
1- Check ground and polarity back to the circuit breaker
2- Ensure the boiler is on a dedicated circuit
3- Check for 30 V DC going to the spark generator
If there is voltage to the spark generator change the spark generator. If there is no voltage to
the spark generator change the main control board.

Baxi Luna HT Troubleshooting Guide
5
E133 Burner Lockout
Weak Spark:
1- Make sure you have 3-5 sparks per second and the boiler is grounded
2- Make sure the spark generator is fastened tightly to the mounting bracket
3- If a weak spark persists follow the procedure outlined in the "No Spark" section
No Flame:
1- Ensure that all gas shutoffs are open and that adequate working gas pressure is
coming to the unit. Refer to the installation manual for gas specifications.
2- Ensure the silicon tube going from the fan to the gas valve is secure and does not
have any moisture or holes in it.
3- Check for 120 V going to coils 1 and 2 on the gas valve
4- If converting to propane gas, try turning the "V" screw (High Fire djustment)an
additional half to full turn counterclockwise
If there is voltage to the gas valve replace the gas valve. If there is no voltage to the gas valve
replace the main control board.
Flame Sensor is not sensing:
1- Check polarity and ground from the boiler back to the circuit breaker
2- Check for 3-5 micro amps going to the board
3- If you do not have 3-5 micro amps try cleaning the flame sensor
Note: Do not clean the flame sensor using sandpaper as it may damage the protective
coating. If the sensor is dirty check you’re venting to ensure you are not recycling products
of combustion. lso ensure that your Q 73 parameters are correct for the type of gas you
are using.
NOTES:
E160 Fan Speed Thresholds not
Reached
1- Check Q 73 fan speed parameters values have been adjusted with respect to gas
type, venting length and altitude. Refer to installation manual for values
If the fan speed parameters are correct then replace the fan.
NOTES:
E168 Communication Lockout
1- Ensure that the boiler is operating on a dedicated circuit, proper polarity and
grounding
2- Check the grounds on the internal pump, gas valve and fan
3- Check for water on the board
4- Unplug the boiler for 20 minutes and disconnect all external controls including the
Q 73. Plug the boiler back in and use a jumper at the M1 block on terminals 1 and
2 to call the boiler on. If an E168 persists replace the main control board.
5- If the boiler fire's up make sure all secondary pumps and controls are grounded and
connect them again one by one
6- If at any point while reconnecting the error code reappears, look for a bad ground or
electrical error on that particular device.
NOTES:

Baxi Luna HT Troubleshooting Guide
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No
Error
code
No DHW
1- Make sure there is a bar in the upper left corner of the Q 73 indicating that the
DHW mode is on
2- Check the DHW hall sensor to ensure it is connected to the inlet group properly
3- Check for debris in the DHW flow sensor
4- Ensure the motorized diverter valve is moving properly
5- Clean the DHW plate heat exchanger
NOTES:
No
Error
code
DHW Not Hot enough
1- Make sure the CH water is going through the plate heat exchanger and not into the
CH loop. If it is going through the CH loop replace the paddles inside the diverter
valve and clean the diverter valve
2- Clean the DHW plate heat exchanger
3- Check the DHW NTC sensor
4- Check the Combustion
NOTES:
No
Error
code
Boiler Short Cycles
1- Make sure the combustion settings are correct for the unit and its application
2- Make sure your heat load is adequate for the boiler
NOTES:
No
Error
code
Boiler makes a Squealing
Noise
1- Check that there is no more than 25% of the system volume of glycol in the system
2- Clean the diverter valve
NOTES:
No
Error
code
Boiler makes a banging
noises
1- Make sure the pump is moving
2- Ensure there is no air in the system
3- Make sure there is no restrictions
NOTES:

Temperature Sensor Testing Chart
Temperature VS. Resistance (°C/Ω)
Part Resistance
Gas Valve 380/1.330 1&3 -1250Ω±5%
1.450/1.650 1&3 - 1180Ω±5%
1.100 EV1–620 Ω±5%
EV2 - 3356Ω±5%
Pump 380/1.330 45 Ω±5%
3 Way Motor 380/1.330 1480 Ω±5%
Fan 380/1.330 9 Ω±5%
Spark Generator 380/1.330 370 Ω±5%
DHW Flow
Sensor
380 2706 Ω±5%