Dimensioning A Standard Low Loss Header; Boiler And System Pumps; Non-Return Valve - DeDietrich Innovens MCA 160 Manual

Fig.42 Low-loss header
X
1/2"
D
Nominal out­ Capacity Q
put
kW /h at ΔT = 20° C "
3
m
300 12.9
450 19.4
600 25.8
750 32.3
900 38.7
1050 45.2
1200 51.6
Fig.43 Boiler resistance
300
250
200
170
150
100
50
0
0 1 2 3 4
Q
7680446 - v.01 - 14082017
Y
1/2"
AD-0000856-01
d
2
2.5
2.5
3
4
4
4
T = 20 K
5 6 6,5 7 8 9 10
[m 3 /h]
AD-0000857-02
7.1.3

Dimensioning a standard low loss header

X Boiler-side connection
Y System-side connection
The low-oss header serves to isolate the boiler circuit from the system cir­
cuit. The resistance of the low-oss header must be very low. The rate of
flow in the low-oss header must not exceed 0.25 m/s. Please refer to the
table for the correct dimensions of a standard low-loss header.
D ∅ or D ⎕
" mm
6 (DN 150) 140 x 140
8 (DN 200 170 x 170
10 (DN 250) 190 x 190
10 (DN 250) 220 x 220
12 (DN 300) 240 x 240
12 (DN 300) 260 x 260
12 (DN 300) 270 x 270
7.1.4

Boiler and system pumps

ΔP Boiler resistance (mbar)
Q Flow rate (m
3
/h)
The total output of the system pump(s) must not be more than the com­
bined capacity Q of the boiler pumps Otherwise, with full take-up, the sys­
tem pump will pump part of the system return water straight to the system
flow. This means that the flow temperature to the system will be lower than
the flow temperature from the boilers. In addition, the selected system
pump must be able to overcome the hydraulic resistance from the system.
Important
A pump is available as an accessory for the MCA 160.
7.1.5

Non-return valve

Install (spring-loaded) non-return valves in the boilers' return pipes to
avoid water flowing back to the boilers that are not in operation. This pre­
vents unwanted water loss.
H A
mm mm
453 604
555 740
641 854
716 955
785 1046
848 1130
906 1208
7 Appendix
B
mm
752
898
1022
1131
1229
1320
1404
MCA 49