I am planning on making a 30x30x30cm heated box. I have an Inkbird ITC 1000F temperature controller that previously heated 2 elements on the sides of the box. There is also a working fan in there. The ITC-1000F lets me dial in a temperature, monitors the temp with a sensor and has 2 relays. One that I can plug a heating element into and one for cooling. The cooling has never been used.
What I am after is a heating pad (which I see Core Electronics does sell some types) or maybe multiple to heat the inside of a box over time. I am able to power the pads via 12V as the current power supply has some 12V connections free.
Here are the questions I am not sure on parts for:
Are 2 heating pads (https://core-electronics.com.au/electric-heating-pad-14cm-x-5cm.html) sufficient to heat up the inside of the box to a range of 50-80C?
What would I need to regulate the voltage coming from 12V? Would a potentiometer do the trick?
The existing temperature controller is just off and on. Is this ok to do or should I look for some sort of capacitor setup to not “shock” the heating pads?
Is there a better method than what I am currently looking at? I did look into heating lights but I feel they may be more of a fire hazard than anything else. The existing box that previously worked fine is made from ACM panel walls with insulation inside. The total area inside is contained within the 30x30x30cm measurement I spoke of earlier.
Please be aware that I have a medical condition so I am not sure if I have asked the questions appropriately or provided enough information. I am more than willing to provide more information if asked as I am not expecting anyone to do the leg work for me… just wanted to see if someone has information that can help me. Thank you in advance.
Just looked at the link for those pads. They are supposed to be wearable so doubt they would reach 50-80 degC. That is pretty hot. They are just resistors so apparently increasing voltage equates to more current more watts so more heat. You say 12V is available. What current capability? Remember heat = power (watts) = volts X current (amps). If you want to make something hot you need power, there is no escaping that. Similar applies to cooling.
A potentiometer would need to control another device to regulate the 12V, but the 12V still needs to supply enough current.
I don’t think heating lights would be any more of a fire hazard than any elements.
You could research Peltier devices. They would be controllable and work off 12V directly but are fairly heavy on current requirements. I don’t know what their maximum temperature is but may get hot enough.
Cheers Bob R
There are other ones on there that look like they would go hotter. Peltier seem to have a cold side that I would need to disapate the temp from but they are very interesting.
Peltier may do. Worth looking at.
They are hot or cold.
In operation passing current one way transfers heat from the “cold” side to the other side. To use as a cooler box good practice would be ro attach a heat sink and suitable fan to get rid of this heat. So you are taking the warmth from within a box and transferring it to the outside to be dissipated by a fan/heatsink arrangement.
However, by reversing the current the opposite occurs. Heat is now transferred from the outside of the box to the inside. The “cold” side of the peltier device is now on the outside and the inside is getting hotter.
I believe this is how some of the non compressor car cooler/heater products work. The compressor fridge/freezers don’t heat. The others do.
I once made a small unit for use in a car. Peltier device mounted in lid of a small “esky” with a reversing switch and a heatsink/fan arrangement. Switch one way = cooler. The other way current reversed, fan stopped, heatsink now a collector of any heat available and we have a hot box. Simple and it worked.
Have a good look at these devices. If they can get hot enough may be just what you are looking for. Low voltage operation and easily controllable with a thermostat or some way of sensing temperature. Could even get exotic and provide some form of PWM control to obtain a more stable and even temperature. Arduino project maybe???
Cheers Bob R