Why Do Hot Water Systems Stop

Why do more Hot Water Systems stop working in Winter?

Have you ever wondered why a hot water system always seems to fail in Winter just when you need it the most? A hot water heater such as an electric storage , gas storage or a continuous flow system works much harder in the cooler months as it tries to heat water from a lower temperature. In an electric water heater, this puts more strain on the valve, heating elements , thermostat and the tank itself. These can be easily repaired at a relevantly small cost.

Thermal Shock

The biggest problem with trying to heat water from a low temperature is a condition called Thermal Shock. So what is Thermal Shock? Thermal Shock is when lower a normal cold water supply flows into already hot water heaters causing a possibly large reaction. The large difference in water temperatures will cause the water heater to expand and contract very quickly and somewhat uncontrollably resulting in the water tank not working properly. This situation may also effect components such as the relief valve, thermostat, and many other components of the water system. The shock will put large strain on welds on your hot water tank. Whether it is a gas hot water or electric water heater, the sudden change in temperature will effect the water heater. Unfortunately the more age that your hot water system has the more likely that the system will stop working properly.


If you make sure that regular maintenance as advised by the manufacturer of the unit is carried out, you will prevent many hot water failures. Check that the thermostat is correctly set and adjust the temperature to suit your hot water system. Make sure that the relief valve is operating as per the owners manual. If your hot water tank is reasonably old you may even need to consider replacing the water heater with a new more efficient model.

What to check if your hot water system is not working properly

If you find yourself with no hot water, here a a couple of quick checks before called a service technician.

Electric: If you have no hot water inside your house

Check that the circuit breaker is on and that you have power to your hot water system.

The next steps applies to electric and gas storage hot water system

Slowly pull the pressure relief valve on the top of the tank. Water coming from this valve is generally very hot so please show caution. If the water is cold and the water inside is cold, you will need and electrician. If the water from the valve is hot but the water inside is tempered or cold, you will need a plumber.