Preheater – home made

[Vermes]

It is a modification of an old preheater, which main disadvantages were:

• temperature was set as the time of heating (experimentally, which after prolonged heating resulted in heating the channel and therefore the temperature was sometimes higher than supposed to be)
• lack of access to the temperature

Assumptions:

• the temperature display
• temperature control through the measurement
• increase the security
• lower the cost

Firstly, the channel was deepened, a little of spiral was added and a second additional protective grid at a height of 1,5cm from the spiral, with ceramic stand in the middle, the second grid is about 1,5cm above the first one, what prevents physical contact with the spiral.



Thermometer PT100 was used while constructing the control of the device. The system operates on the basis of a technical bridge, temperature adjustment is done by bringing the bridge to balance by an adjustable resistor 150ohm.
Switching on the heater is done on the relay. The channel is located on a thick layer of glass wool and isolated from the electronics by the same material. Power cables are thick with thick insulation (also wool) and covered with wool. The multimeter was used as a measure.



Functions:

• the preheater can heat and cool to the temperature set by the potentiometer
• regulated heating
• constant heating without limitation of the temperature
• reaches 500 degrees Celsius

For safety:

• double grid
• thermally and electrically insulated bottom
• enamelled casing
• cleared casing

Below there are some photos of assembled device:



Link to original thread (useful attachment) – Podgrzewacz (preheater) wersja druga