Quote Originally Posted by polyglot View Post
PS 10L of water is 42kJ/K therefore requires 756kJ to bring it up from 20C to 38C. At 12W, that's 17.5 hours assuming NO losses of heat to the atmosphere (perfect insulation). You really want to preheat your water in the kettle
For this purpose I installed a 10 liter boiler in my darkroom that can heat up to 80 degrees Celsius pretty fast. I also have an additional electric water heater for 1 liter standing by.

(BTW: what kind of camera are you holding on your avatar? And shouldn't you hold it upside down since you're in Australia?)