h. Pilot alight but main
i.
Mains electrical supply not
Check mains supply.
burner not igniting.
connected to heater.
ii.
Controls not demanding heat
Check that time control (if fitted) and
room thermostat are operating correctly.
iii.
T3.15A fuse failed.
Replace. If failure occurs again, check
wiring for short circuits.
iv.
Loose connection to room thermo- Check connections.
stat, Limit Switch, gas
control lead, time control, or
transformer.
v.
Transformer open circuit.
Check with test meter electrical assembly.
vi.
Multifunctional control faulty.
Replace Multifunctional control.
vii.
Limit Switch faulty.
Short circuit switch and replace if necessary.
viii. Spillage of flue gasses.
Carry out spillage test and rectify.
ix.
Spillage monitor device (TTB)
Replace
defective
x.
Room thermostat or external
Fit temporary loop in heater thermostat
wiring faulty.
socket. If heater ignites, external circuit
or room thermostat is faulty.
ZZ1031/4
4
5.1.10 It is recommended that at least 600mm of vertical flue should be provided from the top of the draught diverter
(for new installations this shall be incorporated into the flue design). However, when carrying out replacement
installations, an existing flue system may be encountered, where the vertical flue above the appliance to the first
bend is less than 600mm. In the first instance, the installer must judge whether this distance can be achieved
practicably by some means. Where this is not practicable, the existing flue system may be used, providing there is
no evidence of spillage from the old appliance (see 5.1.9 above). Every effort must be made, however, to ensure
that the existing flue complies in every other way with BS 5440 Part 1, including the visual inspection, flue flow
and spillage test described in clause 4.3.2 of the above standard. Flue configurations may be assessed in terms of
equivalent vertical height - details. For air heaters, the minimum equivalent vertical height is 1 metre. The
installer must make a judgement based on his knowledge and experience and the examination and testing
described above as to whether an existing flue system can be used.
Note:
Ventilation of the compartment, room or internal space in which the appliance is to be installed must be checked
for compliance with the requirements of BS 5440 Part 2 ( Ref. Section 3 of these instructions) and upgraded as
necessary.
5.1.11
Calculation method for flue sizing: (BS 5440: Part 1, Appendix A)
a.
This appendix provides a procedure for estimating whether a given flue design is likely to ensure full
clearance of combustion products.
b.
The procedure is based on calculating the ‘equivalent height’ of the flue under consideration, i.e. that
height of the straight vertical circular flue pipe of specific size which will produce the same flow rate as
the flue under consideration. The equivalent height is calculated from the formula:
(K
i
+ K
o
)
e
H
e
= H
a
x
(K
i
+ K
o
)
a
- K
e
H
a
+ SumK
where:
H
e
is the height of the equivalent flue;
H
a
is the vertical height of the actual or proposed flue;
K
i
is the inlet resistance of the flue;
K
o
is the outlet resistance from the flue;
subscript e refers to the equivalent flue diameter;
subscript a refers to the actual or proposed flue diameter;
K
e
is the resistance per unit length of the equivalent flue;
SumK is the resistance (other than the inlet and outlet resistance) of the actual or proposed flue.
Note:
K and SumK are obtained from Table 2. K
o
and K
i
are obtained from Table 3.
c.
Table 2 gives resistance factors for common flue components for use in the formula. Table 3 contains the
appropriate inlet and outlet flue resistances. The flue is likely to be satisfactory if its equivalent height
exceeds 1 metre.
Component
Internal Size
Resistance
Component
Internal Size
Resistance
(mm)
Factor
(mm)
Factor
Flue Blocks
197 x 67
0.85 per metre
45
O
Bend
100 mm pipe
0.61 per
231 x 65
0.65 run
125 mm pipe
0.25 fitting
317 x 63
0.35
150 mm pipe
0.12
140 x 102
0.60
197 x 67
0.30
200 x 75
0.60
231 x 65
0.22
183 x 90
0.45
317 x 63
0.13
Pipe
100
0.78
Raking block
Any
0.30 per block
125
0.25
150
0.12
Adaptor block
Any
0.50
Chimney
213 x 213
0.02
Terminal
100 mm ridge
2.5
125 mm ridge
1.0
90
O
Bend
100 mm pipe
1.22 per
150 mm ridge
0.48
125 mm pipe
0.50 fitting
100 mm GCI
0.6
150 mm pipe
0.24
125 mm GCI
0.25
150 mm GCI
0.12
Table 2
Resistance factors for use in calculating equivalent heights
ZZ1031/4
15
Содержание JB25P MK 5
Страница 18: ...18 ZZ1031 4 Fig 7 PRINCIPAL DIMENSIONS mm ...
