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Let's stop the madness

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:

  1. Depleted Anodes
  2. Electrolysis
  3. Sediment build-up
  4. High temperature & pressure
  5. Softened water
  6. 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.


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."

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1567 Logan Avenue
Winnipeg, Manitoba
R3E 1S5
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