MHS Boilers Ultramax WM 100, Руководство по эксплуатации и техническому обслуживанию, Страница: 28 / 50

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191007
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The flue gas discharge pipe to be used should be airtight and watertight at the joints and connections,
or should be seamless. Horizontal components in the flue pipe should be installed sloping
in the direction of the appliance (minimum 5 cm per meter).
Due to the high operating efficiency of the appliance, there may be condensate formation in the
chimney even at high water temperatures.
The condensate drain should never be blocked!
A direct connection to a brick chimney is not permissible, since the chimney losses must be less
than 17%.
The following table gives the flue gas data for all the types
Maximum flue gas
temperature at full load Quantity of flue gas at
full load Maximum permissible flue
resistance
Type
°C m
3
/h kg/s mbar
WM/45 70 74 0.020 1.4
WM/65 70 113 0.031 1.4
WM/85 70 149 0.041 1.4
WM/100 70 168 0.046 1.4
WM/120 70 209 0.058 2.0
Table 5 flue gas data
Load 100%
Flow temperature 80
°
C
Return temperature 60
°
C
5.3.4.4 Flue
Flue length
Since the boiler is equipped with a “premix burner” with a fan, an overpressure is created in the
boiler. This overpressure is sufficient to overcome the resistance of the burner, the heat exchanger,
and the chimney.
The back pressure outside the boiler depends on:
a. the resistance of the flue pipe
b. the degree of cooling of the combustion gases
c. the resistance of the discharge outlet
The degree of cooling of the combustion gases depends on the following:
a. the insulation value of the flue
b. the ambient temperature
c. the flue system and outlet
There is a maximum overpressure of around 1.4 mbar (140 pa) for the types 45, 65, 85, 100 and
2.0 mbar (200 pa) for the type 120 in the boiler for the flue gas discharge system. (Table 5)