Timeline for How do electric hot water heaters explode and what can be done to prevent that from happening?
Current License: CC BY-SA 4.0
16 events
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| Dec 6, 2019 at 9:43 | comment | added | Russell McMahon | @Harper-ReinstateMonica - Nice reference. Thanks. Useful is: "Most adults will suffer third-degree burns if exposed to 150 degree water for two seconds. Burns will also occur with a six-second exposure to 140 degree water or with a thirty second exposure to 130 degree water. Even if the temperature is 120 degrees, a five minute exposure could result in third-degree burns. " || I shower indefinitely at 113F / 45C. The extra few degrees to 50C/120F would indeed probably be too much. || Mouth interiors can tolerate FAR higher temperatures. | |
| Dec 6, 2019 at 8:38 | comment | added | Russell McMahon | @Luaan Comment only. I'm accustomed to air & water heat transfer capacities. Interesting test: 1. Stand by an idling car with sandals, feet just behind front wheel on a say sub 30C day. 2. Now repeat on a near 50C day (which I managed in Phoenix on above trip). Wow! Pain. Heat transfer rate may be lower (about 800 x less capacity per volume) but good enough to cause pain :-). || I've been burned by dry steam twice. Once mildly from the outlet of a solar vacuum insulated water heater on an overcast day. Cold, wet & dry steam!. And badly enough to spoil my evening in a Taiwanese restaurant. | |
| Dec 6, 2019 at 7:57 | comment | added | Luaan | @RussellMcMahon Air and water temperature have wildly different effects. Air is an isolant - it transfers heat very poorly. Water is wonderful at transferring heat. Not to mention that humans sweat in hot air, which is a powerful temperature control mechanism (especially in climates as dry as the Death Valley). Sweating doesn't work in water for obvious reasons. When you open the oven, you're blasted with hot air at 200 °C with no ill effect. Don't try that with steam at 200 °C (the clouds you see above a pot of boiling water aren't steam, by the way - steam is transparent) :) | |
| Dec 6, 2019 at 7:04 | comment | added | Harper - Reinstate Monica | @RussellMcMahon Oh, but those little 5-10C differences is what'll getcha, much as the French and Germans learned when dealing with the Russian winter during their invasions. They thought they knew what winter was... | |
| Dec 6, 2019 at 6:46 | comment | added | Russell McMahon | @Harper-ReinstateMonica Interest only. I visited Death Valley in 2003. At Bad Water in in mid afternoon thermometers claimed in the mid 50-55C range. At Stovepipe Wells store slightly later they had an impressive "accurate & professional looking" largish dial thermometer on the front of the store out of the sun. It CLAIMED close to 55C. I shower at 45C - nice and hot but very little more is "too hot". 50C = 122F. 55C = 131F. I'm surprised that the max air temperatures I met were quite possibly > 50C / 122F so usefully above my showering temperature BUT by no means unbearable. | |
| Dec 6, 2019 at 3:17 | comment | added | Vikki | "(on a new water heater, the piping won't be there)" - why not? | |
| Dec 6, 2019 at 0:50 | comment | added | Russell McMahon | || USA useful in recirc system. || Legion central and per tap versions. | |
| Dec 6, 2019 at 0:49 | comment | added | Russell McMahon | @Harper-ReinstateMonica I'd rate 140 F/ 60C as "not nice" but bearable for brief exposure. Fall in a shower under that and you are in trouble. Dip your hand in or under it briefly and it hurts but does not mark ongoingly. | I rate 55 C as "just able to keep your hand in. Maybe". I use that mainly as an engineering temperature asessment test rather than as anything to do with tap water. || Do the US have tempering valves? ... Garglabets ... -> OK. You call them mixing valves. We mandate them on a centralised basis. | |
| Dec 5, 2019 at 23:50 | comment | added | Level River St | @Harper-ReinstateMonica the compromise in Europe is to raise the temperature once a week to kill legionella then turn it down again. Admittedly most homeowners are too lazy to do this but it is done in larger, managed buildings. | |
| Dec 5, 2019 at 18:47 | comment | added | Harper - Reinstate Monica | @RussellMcMahon Unfortunately, there is no compromise temperature for scald/legionella. Hot enough to kill legionella is deep into the scalding range. The only Rx the North Americans have found is either a) tankless; or b) combination of scaldy 140F + thermostatic "joystick" faucets rigged to be unable to reach scalding temp. | |
| Dec 5, 2019 at 11:09 | comment | added | Russell McMahon | @Harper-ReinstateMonica In far off NZ -> Yes re legionella. And/but also not above 140 F / 60C for scald safety reasons. A tempering valve will allow higher - at the cost of complexity. I do not know if US systems have these as of right. | |
| Dec 4, 2019 at 19:20 | comment | added | Harper - Reinstate Monica | The "Don't set your temperature too high" is now affected by scientific knowledge about Legionella and other bacteria, which says you need 140F to stop legionella from breeding in your tanked heater. Instructions have not been updated to reflect this, because installation instructions must be approved as part of a heater's UL listing, and manufacturers are unwilling to grind through the UL listing process again. | |
| Dec 4, 2019 at 14:47 | comment | added | JACK | that discharge pipe looks a bit high. | |
| Dec 4, 2019 at 14:43 | comment | added | PhilippNagel | Yes, the valve is usually part of the water heater, but can be replaced if it's faulty. That does require at least partially draining the tank, though. The piping needs to be done custom so that it is routed to a floor drain or somwhere else where the water won't do any damage. | |
| Dec 4, 2019 at 14:34 | comment | added | hotmeatballsoup | Thanks @PhillippNagel (+1) -- it looks like I'm confusing the pressure release valve and the expansion tank. I assume that new electric water heaters come with (new) pressure release valves as well? | |
| Dec 4, 2019 at 14:11 | history | answered | PhilippNagel | CC BY-SA 4.0 |