Baxi LUNA 310 Fi Troubleshooting Manual page 5

BAXI LUNA 310 Fi troubleshooting guide
Fault Cause
Cold water mixing
with hot to taps.
Water temperature
in the winter.
No water pressure Flow restrictor in
at bath tap. boiler.
Little or no hot water Hot and cold pipes
at tap. crossed at boiler.
Dirt in the 3 port
diverter valve.
Boiler slow to start Dirt in DHW venturi.
in DHW mode.
Boiler has been Dirty DHW heat
operating for some exchanger.
time with no problems
until hot/cold problem
ie: with shower
becomes apparent.
#6 (30°f) fault code. Flame failure.
#7 (40°f) fault code. Safety thermostat
activated.
#8 (50°f) fault code. Fault on fan or flue.
#9 (60°f) fault code. Fault on pump or low
system pressure.
#10 (70°f) fault code. Fault on DHW sensor.
#11 (80°f) fault code. Fault on primary
sensor.
Suggested Solutions
▪
Check that the flow from the hot tap is not more than 3.3 GPM (18 seconds
to fill a 1 gallon bucket). If bucket fills faster the tap is mixing with cold water.
▪
During the winter months the cold water temperature entering the boiler can be
10°f lower than in the summer, this will reduce the hot water by 10°f at full flow.
▪
There is not a problem with the hot water pressure . It is essential to
educate the user how the boiler uses the flow regulator to get the correct temperature
rise at full flow. Bath taps are normally 3/4" and in some cases with a 3/4" supply
pipe. With a restrictor fitted to the boiler it may appear as if there is a problem with
the flow rate.
▪
Suspect the installer has connected the hot outlet pipe to the inlet valve. To check
operate the heating in order to warm up the domestic hot water heat exchanger.
Open hot tap; if incorrectly installed, the right hand 1/2" pipe, which should remain co
will become warm.
▪ Diverter valve does not fully close in the DHW mode. To check, with heating
cold or cool, run the hot water and feel the heating supply pipe approx 2-3 feet
from the boiler. If the pipe gets hot this indicates that the 3 port valve is not closing
fully. Strip diverter valve, clean and lubricate, or replace.
▪
If the hot tap needs to be fully opened before the boiler fires, there is dirt in the
venturi. Strip down and clean the water pressure sensor (venturi).
▪
This can be especially true when the boiler has been installed on an existing
system. Suspect contamination from older parts of system. Surfaces of DHW heat
exchanger has been coated, not allowing heat transfer to take place from the primary
water, with the result that the boiler shuts down on its safety thermostat.
▪
If in a hard water area, suspect the potable side of the heat exchanger is scaled up
causing the same problem. De-scale or replace DHW heat exchanger.
▪
Check gas supply, flame signal or ground to boiler.
▪ C
heck continuity across thermostat terminals, when cool more than 1Ω resistance.
▪
Check for scaling or contamination in primary heat exchanger.
▪
Check venting, fan venturi, air switch sensing tubes and air switch.
▪
Check low system pressure, air in system, jammed or faulty pump.
▪
Check DHW sensor for correct resistance reading or is open circuit.
▪
Check primary sensor for correct resistance reading or is open circuit.
Note: in some instances the #6 (30°f) fault will flash as well as another fault code
light. This is because the boiler will show this fault code if the boiler has not detected
a flame after 10 seconds on start up.
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