Cobra Investigates Thermal Expansion in Winter

Cobra investigates thermal expansion and how to avoid unwanted damage to your home’s water heating system during the winter months
19 August 2021 Technical Info
Cobra Investigates Thermal Expansion in Winter
Cobra investigates thermal expansion and how to avoid unwanted damage to your home’s water heating system during the winter months. Cold winter weather results in a greater degree of thermal expansion, placing more pressure on your geyser’s temperature and pressure relief valve (TPRV). Understanding what thermal expansion is and how to protect your home’s plumbing system can help prevent damage,  inconvenience, and the cost of replacing defective valves on account of extremely cold weather. 
 

What is Thermal Expansion?

Much like air, when water is heated it expands, and when it is cooled it contracts. In a standard geyser, the water inside the tank is typically maintained at a temperature of between 50 and 55 degrees Celsius (which can rise to 65 degrees in winter). 
 
Hot water consumption results in heated water leaving the geyser.  This initiates the refilling of the tank, replacing the water that was used by filling the tank from the main water supply. The key to understanding the concept of thermal expansion is that during this stage, the geyser is filled with cold water (compressed) which, during winter months, is even colder and more compressed compared to summer ambient temperatures. Once the geyser tank has refilled sufficiently, the thermostat is triggered and begins to heat the water and causes it to expand. The challenge that thermal expansion causes are that the volume of cold water a geyser can hold is far greater than its capacity to hold expanded, heated water. This places undue pressure on the temperature and pressure relief valve (TPRV) and can cause significant damage. Put in place as an emergency measure, the TPRV is not meant to open and close frequently and should the temperature and pressure relief valve become worn from overuse,  it can tear or lose its seal because of debris from the geyser tank.  The water supply will then need to be turned off until the valve can be replaced.
 
Whether you live in regions where winter temperatures can be extreme, or simply suspect that there may be thermal expansion pressure being placed on your current water heating systems, a thermal expansion tank can either be installed in an existing home water heating system or be pre-installed with new geyser installations. This offers additional insurance against otherwise expensive and inconvenient damage caused by thermal expansion of geyser water in winter.  To find out more, contact an industry-approved plumbing specialist to assess your home’s current water heating system and how this can best be optimised for cold winter conditions.