Solar heating uses heat transfer fluid

Corrosion is a serious issue for providers of solar and ground source / geothermal heating.

In solar and ground source heating systems, corrosion can occur; because, heat transfer fluid transfers the heat energy through metal pipes from the heat source to the radiators. Normally, the heat transfer fluid medium is based on either water, water/glycol mixture, or water containing dissolved salts.

The heat transfer fluids or solar and geothermal systems are similar to those for cooling systems and air conditioning systems. Such systems generally comprise a pump, metal pipes, and fins, or radiators to take heat energy away from a heat source and to radiate that energy back to the environment elsewhere.

Very often, heating systems are multiple component in nature and the pipe work is generally soldered, welded, or bolted together. This means that an uninhibited heat transfer fluid can cause corrosion to a variety of different metals.


It is difficult to completely prevent metals from corroding, other than by regularly applying an impermeable coating. A coating of this kind is usually impractical for the insides of heating and cooling pipes, due to the effects that hot heat transfer fluid can have on paint.

There are several ways in which a maintenance engineer can reduce corrosion by geothermal / solar fluid:

  1. Add a multi-metal corrosion inhibitor, such as Brad-Chem 552, to the fluid
  2. Try to find a less inherently corrosive alternative fluid
  3. Replace metal pipes, pumps & fittings with less susceptible parts

In most cases, owners or engineers add a corrosion inhibitor; this is the simplest, most cost-effective method. Brad-Chem 552 is a multi-metal corrosion inhibitor for a wide range of applications. These applications include solar / geothermal heating, antifreeze, engine coolants, and incidental food contact.

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