Hsotram HK2, Manual

Page: 23 / 36

MANUAL
HK2 – HK4 25-08-2014
Page
23
3.3 Connecting the boiler to the chimney
The boiler must be installed as close as possible to the chimney.
A long length of flue gas piping must - if possible - be avoided and as well more bends which
reduces draught and facilitates the formation of condensate.
The condensate must under no circumstances flow into the boiler.
Use the bends or the straight length with an inspection and soot hatch.
Ensure that the vacuum sealed interlocking pieces are good. If not - use ceramic/glass fiber
seal and/or refractory mastic (according to the technical possibilities of the chimney and the
regulations).
The isolation of the flue gas piping and the connecting flue gas pipes is strongly
recommended.
3.4 Draught (lifting force)
To ensure a good operation of the HK boilers, the pressure of the chimney measured at the
boiler duct shall be between 0.5 and 1.5 mm of water column negative pressure and be
perfectly stable.
It is measured with a pressure meter (for example in liquid) with boiler at raised
temperature (> to 70°C): in cool weather and in normal function.
If the draught is too weak, the evacuation of combustible gas will be insufficient.
If the draught is too strong, the combustion is increases and the flue gas temperature raises -
thereby wasting the fuel. Moreover, the boiler risks over-heating and premature wear of the
hanging plates can appear.
To have a stabilized pressure in the chimney with an HK boiler, it is imperative to install on
the pipe, a stabilizer or suction moderator.
The conditions of installation of the stabilizer:
- The diameter of the stabilizer shall be at least equal the flue gas pipe. It shall be installed
as close as possible to the boiler. Its setting shall be done with a pressure meter.
- If, at the maximum setting (the stabilizer’s shutter is wide open), the pressure is always
superior to the 1.5 mm of the water column, and a second moderator must be installed.