Specifications
Copyright© by AOS 2015. All rights reserved.
Safety
As water is heated, it becomes more corrosive and
expands. These two condions can create safety issues,
but modern water heaters are designed with features to
insure safe operaon. These concepts and other safety
issues will be covered in this secon.
Galvanic Corrosion
A water heater is very much like a large baery. Water is
conducve allowing electrical current to pass through it.
High concentraons of dissolved minerals and an acidic pH
can increase water conducvity.
A water heater tank is made from dierent types of metal
with the tank being steel, the elements being copper, and
ngs which may be brass, steel, galvanized steel or
plasc
Small electrical currents ow between these dierent
types of materials using the water as a conductor.
The material that the current ows from is called the
anode. The material that the current ows to is called the
cathode. The anode’s surface will corrode. This process is
called galvanic corrosion.
The inside of the tank is lined with a glass coang to
prevent galvanic corrosion. The coang is sprayed on in a
liquid form, dried at about 300°F, then red at about
1,600°F to fuse the glass to the steel. Although the glass
lining provides excellent protecon from galvanic
corrosion, small unprotected areas may sll exist such as
the inside of ngs welded to the tank.
To protect any vulnerable areas of the tank, an anode rod
is installed. The anode rod is a sacricial part made of alu-
minum or magnesium. Electrical current will ow from the
anode rod to the tank providing cathodic.
Over me the anode rod will corrode away and will need
to be replaced.
Another way to help protect the tank against galvanic
corrosion is by installing dielectric water connecons.
Dielectric connecons break the electrical circuit between
the tank and the home piping. Dielectric connecons
provide the most benet in older homes where galvanized
pipes were installed. Newer homes usually have copper or
plasc pipes which are less suscepble to galvanic
corrosion.