Brief Summary
This video provides a detailed explanation of the safety features and engineering behind cheap electric space heaters. The key points are:
- Space heaters can be dangerous, but they have multiple safety devices that make many dangerous scenarios unlikely.
- The video demonstrates how the heater's tip-over switch, thermostat, and high-temperature limit switch work to shut off the heater in case of overheating or tipping over.
- The limit switch has an embedded PTC heater that keeps the heater disabled indefinitely after it trips, preventing the heater from restarting automatically.
- The thermostat on these cheap heaters is not very accurate and may not shut off the heater even in very high temperatures.
- The main fire risk with space heaters is not the heater itself, but issues with the home's electrical wiring and outlets. Proper use of space heaters and maintaining electrical systems is crucial.
- Despite the risks, these cheap space heaters can be a useful and safe backup heating option if used properly.
The Safety Features of Cheap Space Heaters
The video starts by addressing the common perception that cheap electric space heaters are dangerous and likely to cause fires. However, the presenter explains that these heaters actually have multiple safety devices that make many dangerous scenarios nearly impossible.
The first safety feature is the tip-over switch, which is actuated by a plastic foot on the bottom of the heater. If the heater is knocked over, this switch will open and shut off the power. Additionally, the heater has been designed to be more bottom-heavy and stable to prevent tipping in the first place.
Next, the heater has a thermostat that reacts to the room temperature and will shut off the heating elements once the desired temperature is reached. While the thermostat is not highly accurate, it can still help maintain a consistent room temperature.
The most important safety feature is the high-temperature limit switch. This switch is normally closed, allowing power to flow to the heating elements. However, if the temperature inside the heater exceeds 75°C (167°F), the switch will open and cut power to the heating elements. This protects against scenarios where the fan fails or the heater becomes blocked, causing the internal temperature to rise dangerously high.
To demonstrate this, the presenter removes the fan from the heater, causing the limit switch to trip and shut off the heater within 15 seconds. He also shows that the switch will trip if the heater's air flow is blocked, such as by placing a griddle in front of it.
The presenter then shows an even more extreme test, where he covers the heater with a flammable beach towel. In less than a minute, the limit switch trips and shuts off the heater, preventing the towel from catching fire.
The video then reveals an additional safety feature - the limit switch has a small PTC heater embedded within it. When the switch opens, this PTC heater activates and keeps the switch above its trip temperature, effectively locking out the heater until it is manually reset by unplugging it and allowing the switch to cool down.
The Limitations of the Thermostat
The presenter then tests the thermostat on the heater and finds that it is not as effective as a safety device as he had expected. Even when the heater is placed in a very hot environment, the thermostat does not shut off the heater until the limit switch trips. This suggests the thermostat is not well-calibrated and cannot be relied upon as a safety feature.
Electrical Safety Concerns with Space Heaters
The video then shifts to discussing the larger fire risks associated with space heaters, which have more to do with the home's electrical wiring and outlets than the heater itself. Space heaters draw a large amount of current, up to 12 amps on a typical 15-amp circuit. This can reveal issues with loose connections or corrosion in the home's wiring, which can lead to overheating and fire.
Additionally, the presenter cautions against using extension cords, power strips, or other adapters with space heaters, as these can introduce poor connections that can also overheat and become fire hazards.
Recommendations and Closing Thoughts
In closing, the presenter recommends that people keep space heaters on hand as emergency backup heating sources, especially if their primary heating system could fail and risk frozen pipes. However, he advises carefully inspecting electrical outlets and avoiding the use of extension cords or power strips.
The presenter also shares his preference for a baseboard-style space heater over the fan-forced type, as it has no moving parts to fail. However, he cautions that the baseboard heater's hotter surfaces make it more dangerous if covered.
Overall, the video provides a comprehensive understanding of the safety features and potential risks associated with cheap electric space heaters, empowering viewers to make informed decisions about their use.
