Operating Information - Viessmann Vitomax HW Series Operating And Service Instructions

Shutdown and preservation
What preservation is for
A depressurised boiler system is at risk from idle-time
corrosion. Such corrosion can be prevented by preser-
vation.
Preservation measures are carried out in areas on the
flue gas side and on the water side of a boiler system.
The type of preservation depends on the type and
duration of the interruption in operation.
Type of preser- Effect
vation
Wet preservation Keeps oxygen away from the boiler
system.
Dry preservation Keeps moisture in the boiler system
to a minimum.
Tab. 1
Brief interruption in operation
Treatment for preservation of the water side
Operating Measures
condition
The boiler is Add oxygen binder to the feedwater 1
switched off. hour before switching off. Dosing: 2
to 3 times the standard dose
The boiler re- Maintain the boiler system pressure
mains on. and temperature.
Tab. 3
Interruption in operation
Treatment for preservation of the water side
Dry preservation
Note
Restarting the system quickly is not possible.
Applications:
■ Prolonged boiler idle periods
■ Risk of frost
See the "Using antifreeze in boilers" chapter in
the technical guide
Application:
1. Drain hot water boilers at < 90 °C.
!
Please note
Draining hot water into the sewage system
causes environmental pollution.
Therefore cool the water to < 35 °C before-
hand. If necessary, collect it in containers.
2. Open the water closures.
(cont.)
3 days
≤
3 days
>
Interruption in operation
Duration Recommendation
3 days Maintain the positive pressure in the boil-
≤
er system incl. all boiler-related equip-
ment (thermal water treatment, etc.).
3 days Select type of preservation.
>
Tab. 2
Basic rule
VdTÜV datasheet TC 1465 "Preserving the water side
of steam boilers"
Recommendation
If using preservation methods that include chemicals
other than those stated here, please consult the manu-
facturers of the chemicals.
Preserving agents: Ammonia or nitrogen
■ A technically demanding form of preservation.
■ Consult the chemical manufacturer before use.
■ The operator must compile system-specific operating
instructions.
Treating the flue gas side
■ Keep heating surfaces dry.
■ Remove severe contamination as it binds moisture.
3. Dry the boiler system thoroughly.
4. Place desiccant (silica gel) in the boiler system in
accordance with the manufacturer's instructions.
Note
Ensure that the desiccant does not come into
direct contact with the boiler material.
5. Close the boiler system.
6. Check the effectiveness of the desiccant regularly.
Wet preservation
1. Fill the boiler system up to the highest possible
level with treated feedwater.
2. Mix oxygen binder, e.g. sodium sulphite, into the
boiler water in accordance with the manufacturer's
instructions. Mix it thoroughly with the boiler water
by means of thermal or mechanical circulation.
Oxygen binder inhibits oxygen corrosion.

Operating information

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