Let's Stop the Madness!
Winnipeg - "Having heard claims that homeowners can double the
hot water capacity of their domestic water heaters by simply increasing
the temperature of the tank and adding a balancing valve (anti-scald
valve) is madness," said Brian Baker, President of Custom
Vac. After numerous calls from customers he felt it was time
again to educate homeowners,
Lets first begin with explaining and understanding what causes
water heaters to fail. The following causes that lead to failure
are:
- Depleted Anodes
- Electrolysis
- Sediment build-up
- High temperature & pressure
- Softened water
- External environment
Depleted
Anodes
- The inside of your water heater is protected only as long as
the anode rod has sufficient sacrificial metal remaining on its
steel core wire. These anodes can be made from magnesium, aluminum
or zinc. In areas where the water is hard typically aluminum anodes
are used and where hot water odor is a problem, zinc alloy anodes
are useful.
Without a functioning anode in your tank, any other measures are
just wasted energy. "Anode's are placed in water heaters as a
means of managing the corrosive environment within the tank. Anodes
allow themselves to be attacked (sacrificed) instead of the steel
tank. Which is in the trade we call them sacrificial anodes,"
Said Baker.
Electrolysis - Just as magnesium anodes corrode
(purposely) in the presence of steel, steel will rust (to the
detriment of your tank) when its near copper or brass. The more
of these metals there is, the more the steel tank will rust. Dielectric
unions and plastic lined steel nipples have been developed to
reduce this electrolytic corrosion. Baker says,
"Care must be taken to ensure that fittings are heated and soldered
prior to being threaded onto the water heater otherwise the steel
nipples may be exposed when the plastic-lining is melted."
Sediment build-up - "Operating water heaters
at elevated temperatures forces minerals out of solution, forming
solids that settle on the bottom of your tank," said Baker. This
sediment is mostly calcium carbonate. Hardness of water is also
a factor, the harder the water the more sediment. When sediment
accumulates in a gas water heater, it forms a barrier between
the water and the flame, slowing heat transfer and increasing
energy use.
The subsequent overheating of the tank bottom can cause two problems.
First the glass lining starts to dissolve at temperatures above
160F. Over time, the steel tank bottom is gradually exposed to
water and potential rusting. Second, severe overheating can weaken
the metal bottom to the point of deforming under normal pressure.
(Temperatures exceeding 1000F have been measured at the bottom
of a severely scaled tank!)
Sediment causes additional problems. In both gas and electric
water heaters, a dense sediment layer can insulate the tank bottom
from the protection of the anode rod. The sediment can also play
host to bacteria. Most of these are not harmful to our health,
but they do make the environment in the sediment more corrosive.
Thus the steel is under harsher attack than with heat and sediment
alone.
High temperature & pressure - Elevated temperatures can cause a more rapid accumulation of sediment and they speed
up chemical reactions. For every temperature rise of 20F, the
chemical reaction speed is about doubled. "Since the rusting reaction
between steel and oxygen is accelerated by heat, avoid high temperatures,"
said Baker.
Excessive water pressure (over 80 (PSI) pounds per square inch)
can also damage a tank. Higher pressures make a tank flex slightly,
causing the glass lining to crack and flake. High pressure may
come from the water supply but most often its caused by the slight
expansion of the water inside the tank, as it is heated to higher
temperatures.
Softened water - Softening water works indirectly
to reduce the service life of your water heater unless you perform
regular maintenance. Softening is accomplished by exchanging the
salt for hardness in the water. This salt is more corrosive to
the anode rod than the calcium carbonate that it replaces. "Since
softened water doubles or triples the speed of an anode's consumption
greatly shortening its useful life," added water heater maintenance
is required.
External environment - "Don't overlook your tanks
surroundings," said Baker. If the air burned in a gas water heater
is damp or carries salt, chlorine, or other corrosive chemicals,
it will attack the tank from the inside of the flue and combustion
chamber. It may even void warranty. Basements especially mechanical
rooms can be a source of chemical soups within the air that the
appliances use in the combustion process when appliance use gas
or oil.
Keep your water heater dry. Many tanks have failed because a plumbing
fitting leaked and rusted through the tank externally. Troublemakers
include the drain valve, heating elements, and hot/cold connections.
Even a loose packing nut on an overhead shut-off valve may leak
and ruin a tank.
"Tanks can fail for any one or a combination of these reasons,
but the statement that increasing the temperature of your water
heater and installing an anti-scald valve will not double your
water heaters capacity. While you may get more water you will
also greatly affect the life expectancy of the water heater for
the reasons we have spoken about, " said Baker.
If homeowners require more hot water
If homeowners are finding that they require a larger capacity
of hot water due to the growth of their family, addition of whirlpool
tub, addition of a new shower, or some other need, consideration
should be given first to adding energy efficient water reducing
devices such as low flow showerheads.
Second, consider changing a few day-to-day activities. I.E. Does
everyone need to shower or bath while the dishwasher and washing
machine are all operating? Finally, if the need still exists for
having more hot water, homeowners may want to consider the age
of their present water heater since older ones may not be very
efficient and could be scaled up.
An economical method of increasing the available amount of hot
water is by adding a second water heater. This is because many
times family's demands increase as the children grow, and then,
demand decreases once they move out. By adding a second water
heater, capacity can be met and as demand decreases, one water
heater can be taken out of service.
Homeowners may be tempted to purchase bigger water heaters, but
remember maintaining water at higher temperatures or greater amounts
of water at storage temperatures costs more and wastes more energy.
"More importantly, when oversized water heaters sit idle, or are
exposed to short draws of hot water the result is stacking in
the tank.
Stacking occurs whenever a water heater develops temperature and
the domestic water is not being drawn. This will normally occur
during many on-off periods that are caused by the users through
the use of many quick short draws of hot water. Most controls
and heaters in use today are not designed to accommodate this
problem.
"It is important to identify and respect this factor since
it will lead to higher temperatures during an initial draw from
the heater resulting in a higher scald potential," said Baker.
Just like the sizing of your furnace or air conditioner, too small
is not good and too big can also create problems.
SAFE KIDS CANADA says...
In Canada, Safe Kids Canada gave a formal presentation to the
Canadian Advisory Council on Plumbing (CACP) requesting that the
temperature settings on water heaters be changed so that they
would not exceed 49C (120F). However Baker says,
"This would have created another problem, bacteria and the potential
for legionellosis to grow in the tanks." A Quebec report titled,
"Prevention of scalding and legionellosis associated with hot
tap water in private homes," recommends that current thermostat
settings be maintained at 60C (140F) and to reduce the risk of
scalding they recommend the installation of an effective anti-scald
device on the water heater outlet to lower the temperature to
49C (120F).
"Unfortunately, not enough is being done by our Industry to educate
consumers and promote products that we sell and install that can
prevent these needless accidents from happening," said Baker.
The 2005 National Plumbing Code will address this issue, but as
Baker says, "Why wait, we know accidents can be prevented today
by simply installing anti-scald valves." Ask you contractor to
install one and prevent your children or an elderly member of
your family from becoming another statistic.
It is important that homeowners educate themselves when purchasing
water heaters and explore all their options. Claims of doubling
the amount of available hot water should be taken with a grain
of salt. Baker hopes that this article will "Stop the madness."
