Rheem 491 Owner's Manual And Installation Instructions page 26

TANK WATER SUPPLY
If the water heater is supplied with water from a tank supply and a pressure pump
system is not installed, then the bottom of the supply tank must be at least 1 m
above the highest point of the hot water plumbing system, including the water
heater. Care must be taken to avoid air locks. The cold water line to the water
heater should be adequately sized and fitted with a full flow gate valve or ball
valve.
HOT WATER DELIVERY
This water heater can deliver water at temperatures which can cause scalding.
It is necessary and we recommend that a temperature limiting device be fitted
®
between a Rheem 491/492 series model water heater and the hot water outlets
in any ablution area such as a bathroom or ensuite, to reduce the risk of scalding.
The installing plumber may have a legal obligation to ensure the installation of
this water heater meets the delivery water temperature requirements of Clause
G12 of the New Zealand Building Code so that scalding water temperatures are
not delivered to a bathroom, ensuite or other ablution area.
Where a temperature limiting device is installed adjacent to the water heater, the
cold water line to the temperature limiting device can be branched off the cold
water line either before or after the isolation valve, pressure limiting valve and
non-return valve to the water heater. If an expansion control valve is required, it
must always be installed after the non-return valve and be the last valve prior to
the water heater.
If a pressure limiting valve is installed on the cold water line to the water heater
and the cold water line to a temperature limiting device branches off before this
valve or from another cold water line in the premises, then a pressure limiting
valve of an equal pressure setting may be required prior to the temperature
limiting device.
Two Temperature Zones Using a Temperature Limiting Device
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