andrews R18 Series Technical Documentation Manual page 64

Inspection of the headers and the fin-tube mounting plate
mating surfaces
Inspect the mating surfaces of the water header, flow/return
manifolds and the fin-tube mounting plate. These should be
clean, smooth and undamaged.
O-ring replacement
Fit new O-rings to all finned-tubes
Fitting and retensioning the water heater and flow/return mani-
fold
Refit the header spacer plate.
Carefully replace the header and hold it in place with one of the
retaining bars with the nuts screwed in finger tight.
Refit the rest of the header retaining bars also with the nuts
screwed in finger tight.
Tighten the retainer bars in four stages and in the sequence
shown in the drawing below to a torque of 25 Nm.
Refit the manifold spacer plate.
Carefully replace the manifolds and hold them in place with one
of the retaining bar with the nuts screwed in finger tight.
Refit the rest of the manifold retaining bars also with the nuts
screwed in finger tight.
Tighten the retainer bars as above (in four stages and in the
sequence shown in fig. 36 to a torque of 25 Nm).
The remainder of the heat exchanger assembly is a reversal of
the removal procedure.
Fig. 35 Expanding the fin-pipe ends
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18IP22B