Installation Instructions
whl-590 Rev. 003 Rel. 003 Date 3.22.18
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B. Backow Preventer
Use a backow preventer specically designed for water heater installations. This valve should be installed on the cold water ll supply line
per local codes.
C. Potable Expansion Tank
A potable hot water expansion tank is required to oset heated water expansion. In most city plumbing systems, the water meter has a
no return or back ow device built into the system to prevent back owing of water into city mains. Some local codes require back ow
preventers on all incoming water supplies. The hot water expansion tank must be listed for potable water use. The expansion tank should be
located on the cold inlet piping close to the water heater.
Expansion Tank
1. Ensure that the potable expansion tank is sized to correctly handle water heater (3.5 gallon capacity), related piping, and connected storage
volume and system temperature.
Undersized expansion tanks cause system water to be lost from the relief valve, causing make-up water to be added. Eventual heater failure
can result due to excessive make-up water addition.
SUCH FAILURE IS NOT COVERED BY WARRANTY.
The expansion tank must be suitable for hot potable water systems.
2. The expansion tank must be located as shown in Applications, this manual, or following recognized design methods. See expansion tank
manufacturer’s instructions for details.
D. Piping the Water Heater
Use both thread tape and pipe dope to connect to the 3/4” domestic water inlet and outlet, and recirculation inlet (if applicable). Tankless
isolation valves between the city water supply and tank inlet are recommended for ease of service.
Use at least the MINIMUM pipe size for all water heater loop piping This is to avoid the possibility of inadequate ow through the water
heater. Using less than the required minimum pipe size and piping could result in system problems, property damage, and premature water
heater failure. Such problems ARE NOT covered by product warranty.
E. Applications
Figure 8 - Piping Symbol Legend