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will change. The accuracy of the calculated efficiency and the ‘automatic trim commissioning’ procedure
will be adversely affected by this. It maybe that these functions should not be used, in which case these
values should be entered as zero.
Options 35.5 to 35.8-Calorific values of fuels/profiles 1 to 4 respectively (0.0 –
99.9) LV3
These option parameters are only available if option 35.0 (inlet temperature sensor) is not set to zero.
If a display of calculated burner efficiency is required, the calorific value of the required fuels must be
entered. May be set between
0.0
and
99.9 MJkg
-1
inclusive.
Note: When firing multiple fuels, the mixture between the fuels fired may vary across the firing range of
the burner. When this happens, the effective hydrocarbon ratio and calorific value of the fuel combination
will change. The accuracy of the calculated efficiency and the ‘automatic trim commissioning’ procedure
will be adversely affected by this. It maybe that these functions should not be used, in which case these
values should be entered as zero.
The following table shows the calorific values and hydrocarbon ratios of several common fuels. These
values should be used as a guide only. If the display is required to show gross efficiency in addition to
entering the gross calorific values a non-zero value for the boiler radiated heat loss MUST be entered.
Fuel
Gross calorific value
Net calorific value
Hydrocarbon ratio
(x10)
Gas
52.8
47.6
3.20
Light oil
45.6
42.8
1.57
Medium oil
43.1
40.8
1.35
Heavy oil
42.9
40.5
1.28
Option 35.9 - Boiler radiated heat loss (0.0 – 9.9%) LV3
This option parameter is only available if option 35.0 (inlet temperature sensor) is not set to zero.
If this option parameter is set to zero the unit will calculate the net efficiency, if non-zero it will calculate
gross efficiency.
For accurate calculation of boiler gross efficiency, this option parameter must be set to the value of the
heat lost through the shell of the boiler at high fire as a percentage of the burner's output at high fire. The
range of this parameter is
0.0
to
9.9%
.
Option 36.0 - Flue temperature alarm select (0/1)
LV3
This option parameter is only available if option 30.0 is non zero.
If option 36.0 is set to
0
, the flue temperature high and low alarms are disabled.
If option 36.0 is set to
1
, the flue temperature high and low alarms are enabled and option parameters
36.1 to 36.4 and 37.1 to 37.4 become available.
Options 36.1 to 36.4 - Flue temperature low alarm values (0 – 999)
LV3
O 2
O 2
Summary of Contents for NEXUS NX6100 series
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