This video presents a detailed teardown and analysis of an inexpensive, unbranded electric water heating tank, likely an "eBay special," intended for undersink use. The host examines its mechanical and electrical components, including the stainless steel tank, heating element, thermostat, safety thermal cutout, and a "gimmicky" digital temperature display. Key findings include a significant discrepancy between the advertised (10L) and actual (6L) tank capacity, as well as a critical discussion on the safety implications of mains-pressure water heaters, particularly the risk of continuous flooding if the tank ruptures. The video also details the internal workings of the electronic display, the design of the water inlet/outlet pipes for thermal stratification, and evaluates the quality of the power cabling, noting potential cost-cutting measures. The host ultimately advises against its use in residential settings prone to flood damage, recommending better-engineered, often more expensive, "vented" systems as a safer alternative.
Summarizing the Water Heater Teardown:
0:00 Introduction to the Unit: The video introduces an electric water heating tank, tested in a new filming location. It features a thermostat, a digital temperature display (described as "superfluous gimmick"), and standard water inlet/outlet ports.
0:20 Tank Specifications and Concerns: The tank is an "eBay special" designed for full mains water pressure. The host raises concerns about local water pressure being close to the unit's limit. It's advertised as a 10-liter stainless steel tank.
0:45 Water Flow Mechanism & Safety: The cold water inlet feeds to the bottom of the tank, and hot water exits from the top, designed for efficient displacement. A pressure relief valve is included to vent water if pressure becomes too high (e.g., due to heating against a closed valve).
2:03 Initial Power-On & Display: The unit's digital display shows green for "keep warm" and red when heating. The host notes the difficulty in shielding the display from bright ambient light.
2:50 Disassembly Process: Accessing the internal components requires removing two screws located inconveniently on the bottom of the unit, making servicing difficult if wall-mounted.
3:49 Electrical Components Revealed: Inside, the unit features a 1.5 kW (8 Amp) heating element. The main power flex is surprisingly thin (0.75mm²). A manual reset thermal cutout acts as a last-resort safety feature against overheating.
4:55 Thermostat and Display Link: A capillary tube from the thermostat and a thermistor (for the digital display) are housed in a sleeve next to the heating element. The display unit gets a permanent power feed and a switched feed from the thermostat to show heating status, deemed a "gimmick."
7:02 Risk of Mains Pressure Tanks: The host emphasizes the significant risk of flooding from continuous mains pressure water spray if the tank were to burst, advising caution.
8:18 Tank Capacity Discrepancy: Upon physical measurement, the "10-liter" tank is found to hold only 6 liters of water, highlighting a misleading specification.
10:59 Internal Water Pipes (Dip Tubes): The cold water inlet pipe extends to the bottom of the tank and is perforated to diffuse incoming cold water without disturbing the hot water at the top. The hot water outlet is a short stub at the top of the tank.
13:46 Relief Valve Functionality: The relief valve includes a one-way valve that can trap pressure, potentially causing the unit to vent water regularly due to thermal expansion.
14:26 Pressurized vs. Vented Systems: The host outlines the differences and safety advantages of "vented" hot water systems. Vented systems are not under mains pressure, only filling on demand, and are safer from catastrophic flooding even if the tank fails. They are, however, more complex to install and use (e.g., taps may drip during heating).
17:05 Digital Thermostat Teardown & Circuit: The "frivolous" digital display uses white LEDs that are prone to fading. Its circuit includes a capacitive dropper for power supply, a microcontroller, and an opto-isolator to detect the thermostat's state. The thermistor for temperature sensing has an unusual 60kΩ value.
20:41 Cost-Optimized Design: The display's decimal points lack LEDs to save cost. The power supply uses a simple, cost-effective capacitor dropper design.
24:25 Power Cable Analysis: The plug is compliant, and the fuse is rated at 5 amps (slightly low for a 1.5 kW unit which draws 6 amps). The copper wire, though confirmed as such after some doubt, feels "strange," suggesting potential cost-optimized alloys.
27:02 Final Recommendation: The unit is deemed unsuitable for residential use in multi-story buildings due to flooding risks but might be acceptable for a workshop. The host recommends investing in better-engineered units like "Aristone" (UK brand) or similar locally available options.