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23.4.3
FLUE GAS & AIR SUPPLY
The flue gas pipes and the air supply pipes must be checked for gas tightness. Also check if the mounting of these pipes is correct, safe and not
damaged. Check the rooftop of the water heater housing for signs of water leakage and traces of water coming from the air supply pipe, the air
vent or any condensate coming from the flue gas pipes.
23.4.4
GAS SUPPLY & SAFETIES
The gas pipes must be checked for gas tightness. Also check if the mounting of these pipes is correct, safe and not damaged. Any built in safeties
should be checked for a correct functioning.
23.4.5
REMOVE THE BURNER UNIT
NOTICE: watch out not to damage the burner plate insulation during this operation!
The burner unit consists of the burner plate, the burner nose and the internal burner. To remove this part for an internal heat exchanger check:
remove the six M6 nuts, the nuts that connect the burner nose to the non-return valve and the ignition cable. After this take out the burner unit
by moving it forward out of the water heater housing.
23.4.6
BURNER
Check the burner surface if it has damages, signs of rust and/or cracks. When the burner surface is damaged the burner must be replaced. The
burner can be cleaned by using a vacuum cleaner or pressurized air.
23.4.7
IGNITION / IONISATION ELECTRODE
When the complete burner is removed, it is also very easy to check the ignition electrode. First check if the distances between the electrodes
and between the electrode and the burner are according to the graph below. When these are not correct, try to bend the electrodes in the right
position. NOTICE: the electrodes undergo high temperatures; therefore the electrodes become hard and are difficult to bend. While bending
used electrodes they might break or burst. Check the electrode, after bending, for any tear/crack and signs of rust. When they are burst/cracked
or rusty, replace the electrode. Also replace the electrode when there is a crack in the ceramic insulation of the electrode. When the electrode
is going to be replaced also the gasket should be renewed.
Point of view in next picture
23.4.8
BURNER DOOR GASKETS
When these gaskets have changed colours at some parts, the rubber has cured and/or is damaged, then these gaskets must be replaced. NOTICE:
Only use the gaskets that are supplied by the water heater manufacturer.
23.5
MOUNTING THE BURNER DOOR CORRECTLY BACK ONTO THE HEAT EXCHANGER:
IMPORTANT:
Before mounting the burner door, make sure that its gaskets and insulation are in excellent shape.
If any signs of damage or ageing are present, these parts must be replaced.
The burner door must be mounted back on the heat exchanger as follows, see picture below:
- Place the burner door with its holes over the six threaded studs, numbered 1 to 6 in the picture.
Careful! When handling too rough or misplacing the holes over the threaded studs, the burner door insulation and/or gaskets may be damaged.
Assure yourself that the door is well positioned with respect to the threaded studs, before pushing it onto the exchanger.
-
Now keep the burner door in place and first turn one flange nut onto stud 1 so the door won't fall down. After that first mount the other
end of the gas/air mixing pipe to the non-return valve, starting at point I, and make sure it's well tightened.
-
Now keep the burner door firmly in place by pushing the gas/air nose with one hand at the middle at point A.
-
Then turn-tighten the flange nuts with the other hand as far as possible onto the threaded studs.
Now the burner door is in place and the nuts can be tightened with a torque key.
Tighten the nuts in the order given in the picture below.
-
The specified torque value for tightening the burner door flange nuts is 8 Nm.
-
D = 8 – 10 mm
D = 0.315 – 0.393 inch
D
3.5 mm / 0.14 inch
114
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