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22
UNICA BHE
6.17
AUTOMATIC BY-PASS & DHW NON-RETURN
VALVE (fig. 32)
Carry out component removal procedure as de-
scribed in 6.4.
Remove the locking pin
(A)
that secures the cover
(B)
to the hydraulic manifold. Using a hooked piece
of wire, carefully withdraw the by-pass cartridge
(C)
and/or DHW non-return cartridge
(D)
. Ensure all seals
are in good condition, taking care to ensure they are
replaced correctly. Replace in the reverse order ensur-
ing the cartridge is facing the correct way.
6.18
EXPANSION VESSEL (fig. 1)
Should the removal and replacement of the ex-
pansion vessel be deemed impractical, an exter-
nal expansion vessel may be fitted to the return
pipe as close to the appliance as possible.
6.16
MAIN HEAT EXCHANGER (fig. 30 & 31)
Carry out component removal procedure as de-
scribed in 6.4. Unclip and remove the three air
chamber covers (front, LH, RH sides). Disconnect
all the wiring connections.
Fig. 29:
Slacken the
gas pipe
(A)
at the air box connection and swing/
rotate of the fan assembly. Disconnect the flow
(B)
, return
(C)
and condense connections on the
heat exchanger. Locate and remove the 4-screws
that secure the heat exchanger to the combustion
chamber
(D)
. Move the heat exchanger to the right
and disconnect it from the flue collector
(E)
. The
heat exchanger can now be lifted up and withdrawn
from the appliance.
fig. 34
6.19
CONDENSE TRAP REMOVAL (fig. 34)
Carry out component removal procedure as de-
scribed in 6.4. Disconnect the 2 upper rubbers
condense pipe
(A)
. Remove the pin
(B)
that se-
cures the trap to the air box plate. Disconnect the
lower rubber condense pipe
(C)
from the condense
trap. Carefully remove the condense trap. Replace
in the reverse order.
A
B
C
fig. 31
Fig. 31:
To remove the fan burner assembly
(A)
locate and remove the 3 external nuts
(B)
. Replace
in the reverse order. Ensure all seals are in good
condition, taking care to ensure they are replaced
correctly.
A
B
Fig. 32
A
D
C
B
fig. 33
6.18.1 EXPANSION VESSEL REMOVAL (with suffi-
cient clearance above, fig. 33)
Carry out component removal procedure as
described in 6.4.
Disconnect the expansion vessel from the flexible
expansion pipe. Locate and remove the screws
(A)
that secure the vessel top holding plate.
The expansion vessel can now be removed. Replace
in the reverse order. Ensure all seals are in good
condition, taking care to ensure they are replaced
correctly.
A