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Dielectric Heat Traps
A heat trap is an energy savings device
for connecting a water heater to the inlet
and outlet water pipes. It is an alternative
to the dielectric nipple.
A water heater is typically responsible
for about 20% of a homeowner’s utility
bill. A water heater can waste up to 15%
of the heat it produces through stand-by
losses. Heat loss occurs through the tank
walls, pipes, and into the surrounding air
of the utility room, garage or basement.
Heat traps prevent this heat loss through
the inlet and outlet pipes. Hot water is
less dense than cold water, it will rise
in the outlet pipe and the cold water
will sink down from the inlet pipe. This
results in a continuous and wasteful
cooling circulation. Camco's flapper style
heat trap design (see diagram) prevents
this process while allowing proper flow
when the heater is in use.
Drain Pans, Dielectric Nipples
& Heat Traps, T & P Valves
Dip Tubes, Run-off Tubes and Anode Rods
Anode Rod: Corrosion Protection
What is it?
It is a simple and inexpensive
system designed to prevent or deter
corrosion of any metal exposed to the
water inside the water heater.
What metal is exposed?
All heaters today are coated on the
inside with a dense, impermeable,
corrosion-resistant coating, but there
is still exposed metal, some intended
and some not: elements, T&P valve
threads, welded joints in the tank,
pin holes in the coating, unprotected
fittings in the waterway, etc.
How does it work?
First, let’s explain the process of
corrosion. When a pure metal
is immersed in an electrolyte
(conductive) – in this instance water –
it tends to dissolve in the solution;
in other words, corrode. In the
process, the atoms of the metal
become positively charged and
accumulate on the metal. Since
most common, commercially used
metals are not pure (usually an alloy)
a single piece of metal will exhibit
areas within the metal with different
potentials (electric charge). The
electric current will flow to the other
areas of the metal with less potential,
or it will flow to another metal of
a lesser charge in the water, taking
minute particles of metal with it,
causing corrosion.
The anode rod is made of a metal
with a higher current potential than
other metals in the water heater. This
is to ensure that the galvanic current
flows from the rod to other exposed
metals, preventing their corrosion. In
other words, the anode rod corrodes
and not the tank or the element.
The anode rod is “self-sacrificing.”
What metals are used?
Aluminum, magnesium and zinc or an
alloy of any of the three. Aluminum
is the most common because it is
inexpensive and works in most areas
of the country.
Why is magnesium used
in some areas?
Not all water has the same
conductivity (e.g., pure water is
much less conductive than seawater.)
Different areas of the country have
different degrees of hardness or may
have several natural chemicals that
could affect conductivity.
Magnesium is the best conductor
of the three, but it is expensive. If
magnesium were used in water with
good conductivity, the rod would not
last very long. It would dissolve at an
undesirable rate, causing the heater to
eventually be unprotected.
What about odor?
The odor is hydrogen sulfide gas. The
source is sulfate-reducing bacteria
present in many water systems. A
water temperature of 140°–170°F
makes for a rich growth medium.
This type of anaerobic bacteria feeds
off the hydrogen gas produced by
the magnesium anode rod. Periodic
flushing of the tank with bleach
solution will reduce the problem.
Water Heater Dip Tube
This is a non-metallic tube inside
the tank under the cold-water
inlet connection. It directs the cold
water to the bottom of the tank, so
as not to cool the hot water in the
top of the tank. The detachment
or deterioration of this tube can be
the cause of insufficient hot water
production.
To inspect the dip tube, turn off
power to the water heater, turn off
the main water supply, and drain
the tank. Disconnect the cold water
inlet pipe from the nipple on the
top of the tank. Remove the nipple
and the dip tube can be removed.
On some heaters the dip tube is
attached to the nipple.
Run-Off Tubes
This is a metal or plastic tube that
is attached to the outlet of the
T&P valve, to safely pipe away the
steam and scalding hot water in the
event the valve activates. It can be
directed to the water heater pan
if the pan is plumbed to a drain
or other disposal area. Orient the
run-off tube so that any discharge
will exit only within 6" above the
structure floor or any distance below
the structure floor. Do not connect
directly to a discharge drain unless
air gap is provided.
There are three configurations of
run-off tubes: side mount, top
mount and center top mount.
Which configuration to use depends
on the location of the T&P valve on
the water heater.
Flapper
Style
Rubber baffle
Temperature and
Pressure Relief Valve
The T&P valve is the most important
safety device on the water heater.
No water heater should be
installed without a T&P valve.
In the event of thermostat
failure (thermostat fails to shut
off properly and continues to
heat water beyond safe limits),
the T&P valve will open and
relieve the pressure in the
tank to prevent catastrophic
explosion. The T&P valve is
set to open at 150 psi and/
or 210°F.
If this valve leaks
or opens within the safe
operating temperatures set
on the thermostats, it should
be replaced.
Water Heater Drain Pans
Water heaters should be set into drain
pans when the heater is installed in a
living space or over a living space, where
water leaks or T&P valve activation
would damage property. Pans should be
plumbed to a proper drain or to a safe
disposal area.
Pans are provided in various diameters to
accommodate all size water heaters. Pans
should be 4" wider in diameter than the
diameter of the water heater.
Metal pans can be used for both gas
and electric water heaters.
Plastic pans should only be used for
electric water heaters.
Dielectric Nipples
When two dissimilar metals are used for
water heater inlet and outlet hook-ups (i.e.,
copper piping to steel tank of the heater),
the connection must be protected from
galvanic corrosion of the threads, which
will cause leaking. Dielectric nipples are
provided with a thermoplastic lining for
this purpose. Use only dielectric fittings or
dielectric heat traps and connectors when
installing a water heater.
Содержание Residential Electric water heater
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