We have bought some really amazing stuff from the Chinese online shops. We’ve also bought stuff that was… less than satisfactory, let’s say. At the prices you pay, you usually just chalk up the bad stuff as a cost of doing business. But [DiodeGoneWild] has a teardown of something that could be very dangerous if it wasn’t up to snuff: an electrically heated shower head. He says they are common in Latin America and have the nickname “suicide showers.”
We’ve seen the cute showerheads that change color, but those take batteries. What we are talking about here connects to the 220V main and draws 30A to instantly heat your shower water. Environmentally, that’s great since you don’t have a tank of water you keep heating and reheating just in case you need hot water. But you wouldn’t throw an AC radio in the tub, so you have to wonder just how safely this thing’s built. Well, you don’t have to wonder, because the videos below are going to show us.
That’s nothing, a look at the design takes a comical turn. Immersion heaters already exist but this design shares nothing with proven methods. The green wire which is a neutral has no place to fasten inside the plastic body. It just goes inside, connects to nothing, while being exposed in the path of the water, presumably to keep water that was too conductive from shocking you. The heating element itself is little more than two coils of (presumably) nichrome wire exposed directly to the water.
There is a low tech pressure switch to prevent the coils from powering up if there’s not enough water pressure. You hope that prevents the unit from bursting into flames.
The shower head is marked 5400 watts — basic math for the 220 V at 30 A has us expecting more like 6600. Based on actual measurements, it looks like the high power coil is 9 ohms and you’ll see in the video, he does the math not only to look at the power consumed but also how much power it should take to heat up water in an instant water heater arrangement like this. It was interesting to watch him measure the flow rate of the shower with a low tech method. The final answer is that the head really needs to draw much more power to really give you a hot shower.
In part 2 below he actually wires the thing up. Having the connections near the leaking water gave us the willies. We also knew it was a bad sign when his GFI tripped from excessive ground current. Turns out, the ground current was just under 200 mA. If that doesn’t scare you, perhaps where he measures 10V in the surrounding water pipes will. There’s even voltage measurable in the shower water although at pretty low current. And while it might not be enough power to really warm the water enough, it does seem to work.
We’ll stick with our passive shower head, thank you. We’ve seen homebrew versions of this that don’t try to heat the water instantly, which is probably a more forgiving arrangement. But there are plenty of easier ways to hack your shower.