Giersch MG2-ZM-L, Installation Instructions Manual

Page: 22 / 30

22/30 22.11.21, Subject to alterations
Calculation principles for gas burner adjustment
22 Calculation principles for
gas burner adjustment
The values given in the tables are setting values for start-up.
The necessary system adjustment must be newly determined in each case.
General:
The calorific value (H
i,n
) of fuel gases is generally specified for the normal state (0°C, 1013 mbar).
Natural gas type E H
i,n
= 10.4 kWh/m
3
Natural gas type LL H
i,n
= 9.3 kWh/m
3
Gas counters measure the volume of gas in the operational state.
Gas flow determination:
To allow the heat generator load to be adjusted correctly, the gas flow rate must be determined in advance.
Example:
Height above sea level 230 m
Atmospheric pressure B (acc. to Tab.) 989 mbar
Gas pressure P
G
at gas meter 20 mbar
Gas temperature
ϑ
G
16°C
Boiler output Q
n
220 kW
Efficiency
η
K
(assumed) 92%
Calorific value H
i,n
10.4 kWh/m
3
Gas flow in standard state (V
n
)
Gas flow in operating state (V
B
)
Conversion factor (f)
Annual average air pressure
Legend:
Q
n
= boiler output [kW]
η
K
= efficiency [%]
H
i,n
= lower standard calorific value [kWh/m
3
]
f = conversion factor
B = atmospheric pressure [mbar]
p
G
= gas pressure at gas meter [mbar]
ϑ
G
= gas temperature at gas meter [°C]
Average geodetic altitude of the
supply region above sea level [m]
from 1 51 101 151 201 251 301 351 401 451 501 551 601 651 701
to 0 50 100 150 200 250 300 350 400 450 500 550 600 650 700 750
Annual average of air pressure (mbar) 1016 1013 1007 1001 995 989 983 977 971 965 959 953 947 942 936 930
V
n
Q
n
η
k
H
×
i n
,
--------------------
220 kW
0 92 10
×
4
kWh
m
3
-----------
, ,
----------------------------------------
= 23
m
3
h
------ = =
V
B
V
n
f
------
23
m
3
h
------
0 94
,
-------------
= 24
m
3
h
------ = =
f
B P
G
+
1013
--------------
273
273
ϑ
G
+
--------------------
×
=