Instruction Manual Dräger MSI EM2 EM200plus-i
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15.6 Average time
30 s
= 30 seconds average time
60 s
= 1 minute average time
15 min
= average time needed for solid fuel combustions
30 min
= 1/2 hour average time
15.7 Draft
Switches on and off the additional measurement of chimney
draft.
15.8 Efficiency and stack loss
The stack loss of normal boilers is calculated as follows:
qA
= (TG - TCA) * [( A2 / (21 - O2) ) + B ]
With: TG
= flue gas temperature
TCA
= combustion air temperature
O2
= oxygen concentration of flue gas in Vol. %
A2, B = fuel type dependent constants
This stack loss is always calculated and displayed as qA and can be printed and stored. The
efficiency is calculated from the stack loss as follows: Eta = 100 - qA.
Is the calculation for condensing boilers enabled the energy has to be considered, which
became free when the flue gas condensates. Now the calculation of the stack loss for con-
densing boilers is:
qA
B
= qA - qA
Cond
At this qA
Cond
is a function, which depends from the fuel type,
the flue gas temperature, and the difference “Tdew – TG”. The
value of this function is zero or negative. Tdew means
“dew point temperature”.
The stack loss for condensing boilers is displayed additionally
as qA-CB, and may be printed and stored. The efficiency for
condensing boilers is calculated from the stack loss qA-CB as
follows: Eta-CB =100 - qA-CB.
