Can an Electric Water Heating Element Temperature be Adjusted by Voltage?

Question

Can an Electric Water Heating Element Temperature be Adjusted by Voltage? i have looked through many webpages for many hours and still cannot find anything.

i have a 2000watt heating element and i want to control water temperature i know i can control this by a simple circuit with a thermistor and heavy duty tansistor but i was just wondering if it could be controlled by voltage easier.

Thanks in advance :)

Answer 1

Well I see this eating around your own head. You know the thermistor or heavy duty transistor could do it. Why go for another voltage controller? Temperature is mostly measured and controlled by the resistive changes in the material and it is quite efficient and simple to work out. If you go for a voltage controller, you'll have to use a VCO (Voltage Controlled Oscillator), which will ultimately use the resistive changes to read its voltage changes. Sweep the voltage controlling off your head and be happy with the simpler system. The earlier won't give you a greater ease than the latter.

Answer 2

a $3 thermal breaker is safer.

Answer 3

It is theoretically possible but difficult to engineer. This is because most heating elements have a small voltage range where they are efficient in producing heat. At higher voltages they burn out and and at lower voltages their resistance is too low so they are not effective. So (for example) you could do it for a voltage controller that works over only 200 to 240 V, but not for the full range up to 240 V.

Answer 4

Just buy a thermal thingy

Answer 5

Generally water heater elements are controlled by duty cycle.  The element is all the way on until the temperature reaches a certain temperature, then turns all the way off until the temperature reaches a related but slightly lower temperature.

The heat output of such an element is directly related to applied voltage, but such a design doesn't respond to the amount of heat lost to water flow.  If you want to increase the voltage when there's more water flow so that more POWER goes to the heater to catch up faster, you will end up with a very complex circuit.  

The traditional "On as high as possible until warm enough" is about as simple as you can get.

Most water heaters have two elements.  The booster one kicks in at a lower temperature once it's established that the main one isn't keeping up.  In such a design, the current is changing, but not the voltage.