Condensation in Water Heaters

Condensation in Water Heaters
May 31, 2012 Lorelie

When there is condensation occurring in your water heater, it does not necessarily mean that your water heater unit is leaking.  When your gas-powered water heater unit is working, condensation is considered to be just a normal occurrence.

Condensation in Water Heaters – What It Means

When gas burns, there is a lot of moisture in the products of combustion, and when the flue gas product known as water vapor is chilled below the dew point, water heater condensation occurs.  The dew point is known as the temperature at which water vapor turns into its liquid state, called condensate.

When the main gas burner is turned on, the water heater produces hot flue gases, which then turn into condensate upon contact with colder surfaces.  Condensation on these colder surfaces may be caused by the piping which is cooled by the low incoming water temperature that flows through.

The Symptoms and Which Part of the Water Heater Condensation Occurs

In order for you to properly troubleshoot your water heater that has problems with condensation, you need to first recognize the symptoms and know how to find which part of the water heater unit condensates.

Shortly after you start the water heater on, when the gas-powered water heater is filled with cold water and the main burner is turned ON, the water heater unit will then release the condensate.  One of the primary symptoms of condensation in water heaters that you will notice is a puddle of water forming on the floor just below the unit.

Take note that water heater condensation normally happens especially when you are dealing with new heating appliances as well as when you are using them for the first time.

You will also notice a condensate after a long draw of hot water in a short period of time and when the refill water is very cold.

When the temperature setting is set too low, condensation may possibly occur as well.  The simple solution to this is to just increase the temperature.

An undersized water heater unit is actually another reason for the formation of more condensation, and even with a water heater that is of proper size, you could expect some condensation as well.  The water heater you avail must be of proper size, so that it will meet your family’s demand for hot water usage, for dishwashing, for showering, clothes washing, etc.

Typical Problems and How to Solve Water Heater Condensation

Condensation occurring in water heater units is normal and it is noticeable during the winter and early spring when the outside temperatures are lowest, but excessive water heater condensation isn’t actually considered to be normal.  Excessive water heater condensation can potentially cause pilot light outage and premature corrosion of the burner area and the tank itself.  Small red or black granules can be seen on the main burner and at the top of the water heater.

Carbonic acid and hydrocarbons are found in the condensate, and they are responsible for causing the water heater to corrode.  The most exposed parts to condensation are baffles, flue tubes and burners.

Moisture coming from the combustion products will condense on the cooler tank and then form water drops which might drip onto the burner or any other hot surface, resulting in the characteristic frying, sizzling or popping noise within the burner area.

Continuous exposure to condensation will eventually weaken the flue tube.  Also, it can affect the gas combustion, producing toxic carbon monoxide.

Due to the suddenness and the amount of condensate, the problem can be diagnosed as the leaking.  Remember that about one half of gallon of condensate during every hour of operation is normal for a water heater at home.  It takes about one to two hours for the water heater tank to warm up, so the condensation should disappear.

Due to the fact that Energy Star water heaters and new high efficient units are utilizing powerful gas burners; and combining it with state-of-the-art advanced technology to extract even more heat from the flames and flues, these units will tend to condensate more than the older water heater models that are using less energy.

One of the most practical solutions when trying to troubleshoot condensation in water heaters is a good venting so the gas appliances will operate efficiently, and vent the products of combustion along with the water vapor properly.

Because the cooler flue gases are somewhat partly responsible for the problem of condensation in water heater units, it is advised that you raise the supply air temperature, increase the stored water temperature, or increase the size of the water heater tank.

A suitable metal drain pan which is at least 2 inches in width than the water heater unit must be installed under the water heater in order to collect the condensate and thus prevent possible damage to the unit.

How to Distinguish Whether Your Water Heater is Condensing or Leaking

Ensure that there is no water under the water heater.  If there is any, wipe it up immediately.

Turn the thermostat on the gas control valve to the pilot position.

Simply wait for a few hours, or maybe approximately one day, to check if any water accumulated under the water heater unit.

When the water is heated at above 110 F, condensation should stop.

If there is no water present under the water heater, then it is condensing.  If there is a puddle present, then it might be leaking.

How to Prevent Problems Associated with Water Heater Condensation

Condensing water heaters, such as that of Vertex from AO Smith, requires a drain that is located close to the water heater unit so the condensate can drain properly and safely.  This water heater has three different places where the condensate drains from, the bottom of the unit and where the blower assembly is normally installed.

Make sure that the condensate flow is clear and free of debris and the drain will not let backflow through the hose.  This is extremely important especially during the cold winter days.

In the case of the power vent units, in order to avoid problems associated with water heater condensation, the vent pipe must always slope downward away from the blower.  If this is not possible, then an adequate water heater condensation trap or drain must be provided.

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