Supplied By www.heating spares.co Tel. 0161 620 6677
9.3
GAS CONTROL VALVE
Refer to Figures 34, 35 & 36
a)
Remove casing and control panels as described in section 6.2.
b)
Unscrew the gas valve electrical plug and disconnect from the
gas valve.
c)
Ensuring the gas isolating cock is in the off position, undo the
union nut holding the gas valve feed pipe to the gas isolating
cock and disconnect.
d)
Disengage the gas valve feed pipe grommet from the casing
by pushing it upwards.
e)
Remove the three Torx screws (T-25) of the air/gas channel
fixing to the combustion chamber door (figure 34).
f)
Remove the gas control valve, fan and air/gas channel as one
complete assembly by carefully pulling forward and rotating
anticlockwise. Then disengage the gas valve feed pipe from the
casing by lifting the assembly upwards.
g)
With the assembly on a bench, unscrew and remove the four
screws securing the gas valve feed pipe, (figure 35).
Note:
Newer versions may have a single flange nut securing the
gas feed pipe.
h)
Unscrew the three Torx screws (T-20) securing the gas valve
onto the fan (figure 36).
i)
Replace the gas valve and re-assemble in reverse order.
j)
Ensure all seals in particular the burner seal (figure 40) and
gas valve feed pipe seal are in good order and fitted correctly
then check for gas soundness.
36
34
35
If a new gas valve is fitted it must be adjusted as per the
instructions that are supplied with the new gas valve.
A suitable, calibrated flue gas analyser is required to measure the
CO
2
.
REPLACEMENT AND SET-UP
9.3.1
GAS CONTROL VALVE REMOVAL,
9.3.2
COMBUSTION CHECK SET-UP
When installing, commissioning or servicing
a gas appliance that incorporates a pre-mix
burner and zero-set governor, because it is
not possible to measure an operating
pressure the engineer should first check that the gas
supply is metered and ascertain whether it is possible
to measure the gas rate. If the gas input rate can be
measured then the requirements of GSIUR 26(9) can be
met, including any specific requirements in
manufacturers’ instructions.
If gas input rate cannot be measured then, to satisfy
the intent of GSIUR 26(9), the engineer shall measure
the combustion quality of the appliance in accordance
with BS 7967 or the manufacturers’ instructions.
If the engineer does not have the required equipment
and no alternative test is specified by the manufacturer
then the appliance shall be turned off and disconnected
as an un-commissioned appliance until such time that
equipment is available to undertake such tests.
!
3 TORX SCREWS
4 SCREWS
3 TORX SCREWS
32
751094 ACE HE INST MANUAL:751094 ACE HE 28/9/10 09:46 Page 34
