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4.8.
Correction values for different operating conditions
4.8.1.
Flue gas temperature correction values HE
Average boiler water temperature
Flue gas temperature difference
Excess air
Flue gas temperature difference
4.8.2.
Modulation range
In chapter 4.5 modulation ranges are indicated for an average boiler water temperature of tm = 70°C.
Since the minimum power of the boiler is limited by the minimum allowable flue gas temperature, the modulation
range increases when the average boiler temperature increases. This is exemplary illustrated in the figure below
(example for oil operation with a minimum flue temperature of 120°C).
Flue gas temperature – Boiler power diagram, example for two average boiler water temperatures
4.8.3.
Stand-by loss correction values
Average temperature difference *
Stand-by loss correction
* Average temperature difference = Average boiler water temperature minus ambient air temperature
Average boiler water temperature = Average of supply and return temperature
We reserve the right to make changes to dimensions and construction
Melbury HE, C 530 - 3000
tm
°C
50
60
∆t
K
- 16
- 8
1.10
1.15
λ
-6
-3
∆t
K
°C
30
∆tm
%
-40
∆qB
17
70
80
90
± 0
+ 8
+ 16
1.20
1.25
1.30
± 0
+3
+6
40
50
60
-20
± 0
20
Hamworthy Heating Limited – Dorset BH17 ONF
100
+ 24
1.35
+8
70
40
edition 12.2020
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