Boilers are made of metal, but they spend their working life with constant water and oxygen exposure. These are the elements that lead to corrosion problems, which is a major issue a boiler faces. 

1. Heat Exchange Failure

The heat exchanger at the bottom of the boiler is responsible for keeping the water inside at the desired temperature. As a metal component, it is very prone to corrosion. Once the damage becomes severe, the heat exchange fails and the water will no longer heat up properly in the tank. 

2. Pressure Buildup

In later stages of corrosion, before leaks occur but after a quantity of the tank has begun to flake and break down, high-pressure issues may occur. This is because sedimentation is building up inside of the boiler tank due to the degrading metal. Hard water sedimentation, a major cause of corrosion, can also build up. The result is less space to hold the heated water, which leads to increased pressure inside the boiler tank. 

3. Rusty Water

When draining a boiler to let off pressure or as part of normal service, take the time to examine the water. It should ideally be clear with little to no sediment suspended within the liquid. If the water is rusty or brown in color, then corrosion is likely affecting the inside of the boiler tank. There may also be metal sediment or grainy brown flakes suspended in the water if the metal is breaking apart due to corrosion. 

4. Tank Leaks

Corrosion literally eats away at a metal boiler tank from the inside out. Eventually, holes and cracks will appear in the metal because of this. You may notice standing water beneath the boiler or in the overflow pan, but there is no sign that the pressure overflow was triggered. When there is standing water without a high-pressure situation, then you can be assured that there is a leak somewhere in the tank. 

5. Pitting

Pitting isn't always obvious from the outside. It occurs when corrosion in the tank or the pipes leading from the boiler begins to break down from the flakes of metal the corrosion causes. A lot of very small pinhole leaks on the tank can be a sign of pitting. You may also notice pitting inside the outlet pipes from the boiler in the event one springs a leak and requires replacement. 

Contact a boiler service if you suspect that corrosion may be a problem in your boiler system.