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INJECTOR
SIZE
GAS RATE
m3/h (ft3/h)
INPUT
kW(Btu/h)
OUTPUT
kW(Btu/h)
BURNER PRESSURE
mbar in wg
Min
Max
4.9mm 3.00(105.9)
3.31(117.0)
3.62(128.0)
32.1(109500)
35.4(121000)
38.8(132500)
23.5(80000)
26.4(90000)
29.3(100000)
10.0
12.0
14.0
4.0
4.8
5.6
CIRCULATION PUMP SELECTION
The resistance through the heat exchanger when operating
with a water flow rate producing an 11
0
C temperature riseat
maximum boiler output are shown in TABLE 2. If other
controls, such as three-position valves are used in the
system, the resistance through them, quoted in their
manufacturer’s literature must be taken into account. The
pump may be fitted on either the flow or return and MUST
be wired directly to the boiler terminal block, see FIG. 24. It
must be fitted with two isolating valves which are positioned
as close to the pump as possible. Closing of any valve must
always leave the open vent unobstructed.
TABLE 2
WATER FLOW RATE
BOILER RESISTANCE
WITH DISC WITHOUT DISC
litres/sec gal/min KN/m2 in wg KN/m2 in wg
0.637 8.4 17.8 72 5.2 21
NOTE: Great care should be taken when selecting a
pump to ensure that the correct flow rate is achieved.
Fully pumped systems should be designed so that the
system differential is no greater than 15ºC.
FIG. 5 PRESSURE LOSS ACROSS BOILER
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