Dry Preservation; Preserving The Hot Gas Side - Viessmann VITOMAX 200-HS Operating And Service Instructions

Operating information
Preservation

Dry preservation

Note
This method is used when longer idle
periods are expected and to ensure pro-
tection against frost. This method means
that a quick return of the system into use
is not possible.
Complete drying out
After cooling down in the idle stage, the
boiler will be quickly drained at a pres-
sure of approx. 3 bar. Observe the max-
imum permissible temperature for drain-
ing into the public sewage system.
Where required, catch the water in a col-
lecting tank and drain it after it has
cooled down sufficiently.
Flush steam boilers with a high salt con-
tent in their boiler water (> 5 000 µS/cm)
once more on the water side. Afterwards,
open all man, head and hand holes.

Preserving the hot gas side

Flue gas side
After the boiler has been taken out of
use, clean the heating surfaces on their
hot gas side. The normal draught
ensures that the heating surfaces on the
hot gas side are adequately dried. Accel-
erate the process by means of a fan
heater; if required open the flue gas shut-
off dampers for this process and then
close again.
It is recommended to treat the combus-
tion chamber and the hot gas flues with
preserving oil (graphite or boiled oil).
This can be sprayed on or applied with a
brush. The boiler doors remain open.
20
(cont.)
Dry out components, such as econo-
misers, separately.
Position desiccants (e.g. silica gel, blue
gel) in shallow bowls inside the open and
drying boiler or hang them inside the
boiler so that any contact with the boiler
material is safely prevented. Then close
the boiler. Check the desiccants at least
monthly. They should be replaced as
and when required.
Preservation with ammonia or nitro-
gen
These methods require extensive tech-
nical and technological effort. When
using these preserving methods, formu-
late system-specific operating instruc-
tions.
Keep the surfaces dry during idle periods
(by adding a desiccant such as silica gel
or by air circulation via a connected
dryer).
A dry preservation is not recommended
under special installation conditions in
areas with high relative humidity (in the
tropics, near the sea).