Guidelines for immersion heater installation into boilers, autoclaves, sterilizers and other water heating applications where a mounting flange and gasket are required.

Immersion Heater Care and Maintenance

The life of immersion heaters can often be extended by periodic maintenance.  Over time, deposits of minerals build up on the surface of heater tubes.  This build-up reduces the efficiency of the heater.  This mineral scale is a thermal insulator and restricts the heat energy from actually reaching the water.  Since the water doesn't heat efficiently, the heater is working more than neccessary and will eventually overheat itself and burn out internally.


Factors that make this situation worse:

  • Hard water or poor water quality.  This is often an environmental situation that can't easily be resolved.  Water filters coming into the tank will help.  The more minerals there are in the water flowing into the system, the more there are that will be deposited on the tubes.
  • High watt density on the surface of the heater tube.  This is a design issue that is generaly restricted by space constraints.  A high power heater in a small physical space creates this situation.  Our heaters are designed to have as much surface area as possible and still fit inside the available space, but we cannot change the physics of surface area/power.  For your reference, our immersion heater drawings all specify the tube watt density (surface load) on the drawings.
  • Over-voltage supply and spikes.  These also often can't be controlled, but never use a heater at more than it's rated voltage.  Over-voltage conditions increase the power output significantly beyond what the heater was designed for.  See the point above for what happens.  Under-voltage is OK, but the reduced power might cause increased heat-up time and process times.
  • Poor water circulation or low water conditions.  Either of these situations will cause overheating at a very localized area where the water is not removing heat from the tube.  This often creates a catastrophic failure.
  • Infrequent cleaning.  This is something that can be controlled.  Periodic removal and cleaning of the heater tubes is mandatory and should be planned as normal periodic maintenace.  The schedule for this maintenance will be determined by the factors previously mentioned.  When replacing heaters, remember to disconnect the electrical power and properly lock out the equipment.  Remember to install a new gaskets, properly torque the bolts and follow standard installation guidelines.