Rheem Gas Domestic Outdoor Water Heater Installation And Owner's Manual page 19

INSTALLATION
SADDLING - PIPE WORK
To prevent damage to the cylinder when attaching pipe clips or saddles to the
water heater jacket, we recommend the use of self-drilling screws with a
maximum length of 12 mm. Should pre drilling be required, extreme caution
must be observed when penetrating the jacket of the water heater.
Note: Damage to the cylinder as a result of saddling to the jacket will void
the warranty.
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