4-7
MAINTENANCE
VFC 15-150, VFC 45-225 MODULATING GAS BOILERS
angle-driver to reach past the gas valve, or a stubby Phillips screwdriver
for enhanced working space.
ii.
Three vinyl hoses do not need to be disconnected, but if that is chosen
ensure they are marked for reinstallation. Avoid placing pressure on the
disk-shaped air pressure sensor, which can damage the sensor.
iii.
Lift away the FC/ Fan assembly and stow safely.
c.
Perform steps 1(h) to (k) as listed above, and protect the gas valve from
water and dirt.
Use this method if site conditions provide a risk of debris within the
combustion air (dirty environment with no combustion air filtration). This
offers open access for cleaning of the swirl plate, air intake housing and fan
inlet. Take care to protect the air intake and gas valve components left in
place.
3.
A third option available is a variation of #2, but substituting disassembly of
gas inlet piping (e.g. at a union near the drop leg) in place of splitting the fan/
gas valve in situ. This eliminates having to deal blind with the back screw
per 2(b)(i) above; rather it can be handled “face-on” on a work bench. For
this option, at Step 1(c), also unplug the gas valve electrical connection by
removing the 1/4” gas valve harness connector screw, mark and disconnect
the vinyl hoses from the intake air housing and gas valve; after Step 1(f)
remove the 4 small Phillips screws at the gas valve inlet. Block off the
combustion air intake pipe to prevent debris from falling inside.
With either approach selected, leave undisturbed the outer refractory ring unless
there are signs of damage. If replacement is required, make specific precautions
for silica dust management then pry up the material (likely in several pieces). Bag
with care to seal off, and dispose.
RE-ASSEMBLY
1.
Inspect the inner refractory disk (replace as appropriate), and reinsert per
noted alignment. If the outer refractory ring requires replacement, first
perform a dry fit test (including placement of the HX lid overtop with the
HX: lid gasket properly positioned) to confirm positive engagement of lid to
refractory for a good thermal seal. Apply a thin layer of mouldable refractory
to the water pipes and header to be covered then insert the new outer ring.
Apply gentle pressure until the ring’s upper surface is level and approx 1/16”
(1-1.5 mm) proud to the HX rim.
2.
Inspect the HX: lid gasket: look for cracks, deterioration or signs of gas
bypass. Replace if necessary. Confirm it is in place and offers a positive
sealing surface.
3.
Place the HX lid over the gasket, reconfirming that 1/16” (1-1.5 mm) is
available for compression on bolt tightening. Install the 4 Lid-to-HX bolts; with
a 17mm wrench or socket, tighten with light force until bolt starts to get tight,
then final tighten with 1/2 to 1 extra turn.. Over-tightening will cause lid to
warp and possible leakage of fumes or flames.
4.
Inspect the lower burner-to-HX gasket. Look for cracks, deterioration or signs
of gas bypass. Install original or replace as necessary.
5.
Insert the burner, ensuring the metal mesh seam is rotated away from the
ignitor location.
6.
Move the Fan Coupler into place, then:
a.
Under option 1 – replace the paper gasket after applying silicone to each
side; install the 4 small Phillips bolts at the Fan: FC interface
b.
Under option 2 – install the 3 standard Phillips screws to reattach the Fan
and swirl plate to the gas valve
Vellumoid paper
gasket VFC15-150
O-Ring, VFC 45-225
Figure 33: Gas Valve Detail
Summary of Contents for VFC 15-150
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