Troubleshooting - Viessmann Vitomax HS M73 Operating And Service Instructions

Diagnosis
Fault/ System char- Cause of fault
acteristics
Burner does not start. No voltage present.
Safety chain activated.
Burner fault indicator illuminates.
Fuel supply is interrupted.
Oxygen corrosion Topping up with unsuitable water.
(water side)
Boiler has been too often taken out of serv-
ice without being preserved.
Flue gas temperature The heat transfer is reduced by contamina-
is too high. tion on the flue gas and water sides.
The rated boiler heating output is exceeded.
Discharge from safety The discharge pressure does not match the
valve. max. permissible operating pressure.
Operating pressure is too high.
Valve seat is contaminated.
Water trap pipe (upstream of pressure regu-
lator) is blocked.
Boiler produces satu- Boiler water alkalinity is too high.
rated vapour.
Water level is set too high.
Steam hammer inside Feedwater is not fed in at the feedwater con-
boiler nector.
Steam knocking in- The check valve in the feedwater line is
side the condensate missing or faulty.
container/feedwater
Steam trap in the system is faulty.
tank.
U-bends buckle.
Boiler water level is Steam distributor above the boiler is not ade-
too high. quately drained.
Water level is set too high.
Water level limiter Shut-off valve in the feedwater line is closed. Open the shut-off valve.
switches off.
There is no feedwater in the feedwater tank.
Feedwater pump or water level controller is
faulty.
Water level limiter Severe water level fluctuations through ex-
switches off. cessive alkalinity.
Incorrect electrode length.

Troubleshooting

Measure
Switch ON the mains isolator.
Check safety equipment.
Press reset button on the burner control
unit.
Check shut-off valves in the fuel supply
line and filter for obstructions.
Remedy other faults in accordance with
the burner manufacturer's instructions.
Check water treatment system and injec-
tion system in accordance with
VdTÜV guideline.
Switch to standby (95 °C) instead of a
complete shut down.
Clean boiler.
Check burner heating output.
Check discharge pressure and replace
safety valve if necessary.
Check and correct adjustment of pressure
regulator and pressure limiter.
Clean valve seat.
Clean pipes.
Blow-down boiler at regular intervals, in-
stall a TDS unit where necessary, treat
water in accordance with the VdTÜV
guidelines and notes from page 19 on-
wards, drain downstream steam line.
Check electrode length.
Connect feedwater line to the correct con-
nector.
Install or clean the check valve (observe
the flow direction).
Identify and repair faulty steam trap.
Reduce steam pressure.
Install a steam trap.
Check electrode length.
Check mains water connection.
Determine the cause of the damage to the
water pump and water level controller in
accordance with the installation instruc-
tions.
Drain water from boiler and feedwater
tank. Refill with treated water. Blow down
more frequently. Check water treatment
system.
Check and adapt electrode length.
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