Installation Manual

H-Series Demand Duo™ 2 Installation and Operation Manual 35
The storage tank is equipped with two magnesi-
um anodes designed to extend the life of the
storage tank. Slowly consumed over time, the
anode protects the glass-lined tank from corro-
sion. Rinnai strongly recommends to inspect the
anodes every two (2) years. If more than half of
the anodes have been consumed, they should
be replaced. Instructions on how to change the
anodes can be obtained from the
manufacturer.
The longevity of the storage tank can be re-
duced when a water softener is introduced to
fight hard water. Sodium salts added by a sof-
tener can make the water extremely conductive;
therefore, the anodes are consumed at a faster
rate. In such conditions, the anodes should be
inspected on a yearly basis.
In certain conditions, the anodes may react with
the water, producing discolored or smelly water.
The most common complaint is hot water that
smells like rotten eggs. This is the result of the
reaction between the anode and hydrogen sul-
phide gas dissolved in the water, which is com-
mon in well systems. This issue can usually be
eliminated or reduced by changing the magne-
sium anodes to aluminum anodes and by chlo-
rinating the storage tank and plumbing system.
If the problem continues, special filtration equip-
ment may be required. Under no circumstances
are the anodes to be removed from the water
heater on a permanent basis.
Removal of the anodes will lead to prema-
ture failure of the water heater and will void
the warranty.
Drain a pail of water through the drain valve at
least once a year. This will remove excess
sediment from the bottom of the tank. This
sediment, if allowed to accumulate, will reduce
the efficiency and the life of the tank.
To drain the storage tank:
1. Turn off power to the system by unplugging
power to tankless water heaters and digital
controller. (The system will not be fully shut
down by pressing the Power button on the
controller.)
2. Close the cold water supply manual shut-off
valve.
3. Connect one end of a garden hose to the
storage tank drain valve and put the other
end next to a free-flowing drain.
4. Open the drain valve by turning the knob
counter-clockwise.
5. Open a hot water faucet to allow air into the
system.
Drain
Valve
Cold Water Supply Valve
Anodes
Caps
Storage Tank Anodes Storage Tank