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First, thanks for taking the time to publish this design and its predecessor - the information has been very helpful. In studying the design, I'd like to offer some hopefully constructive thoughts.The solid state relay canget too hot, if it is on for a long time, for instance if initially heatingcold water to cooking temperature. I ran the SSR25 sitting on a bench in freeair, powering a 1500 watt element, and the bottom of the SSR rapidly exceeded 80°C, themaximum operating temperature specification. The fix is a small heatsink andfan, such as one used to cool VGA graphics chips such as this one on ebay: 40x40mm 2 Pins Connector PC VGA Video CardHeatsink Cooler Cooling Fan ClearThe problem is that these fans need a 12 volt power supply.There are small modules on ebay that would work fine, like this one: 12V 450mA Isolated Switch Power Module LEDPower AC-DC 220 To 5V/12VAnd,once you have a 12 volt power supply, you no longer need a temperaturecontroller that can operate from 110v, and instead can use something smallerlike this one: DC 12V 20A Digital LED Thermostat RelayTemperature Controller w/ SensorThe final recommendation is to get rid of the mechanical relayin the temperature controller. If you use the SSR25-DA solid state relayinstead of the SSR25-AA relay, it can be controlled with a 12 volt DC signal.The 12V temperature controller above applies 12 volts to operate the coil onits relay. So, remove the relay, and use the signals going to the coil pins onthe relay to operate the SSR. (Be sure to get the polarity right whenwiring the relay drive signal to the SSR!).Of therecommendations above, I think the fan/heatsink is pretty important, which also requires the 12 power supply module to power the fan. The other suggestions are how I'm building my cooker, but certainly not essential to success.
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