Burnham INDEPENDENCE IN10 CANADA Installation & Service Instructions Manual page 21

G.
If a long term pressure test of the hydronic system is
required, the boiler should first be isolated to avoid a
pressure loss due to the escape of air trapped in the
boiler.
To perform a long term pressure test including the
boiler, ALL trapped air must first be removed from the
boiler.
A loss of pressure during such a test, with no visible
water leakage, is an indication that the boiler contained
trapped air.
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