If you really think you need an E-Stop (the main power switch will perform the same function), then use and NC mushroom head switch wired in series with the main power switch as shown in the red lines by
@Brumateur , but leave out the green wires, fuse and resister that short a hot to ground.
The way your current sensing coil for the V/A meter is placed, you will only be measuring the current used by the element, but not the fan or pump. If this is how you want it, then the design is good. If you want to measure the pump and/or fan current as well as the element current, then you need to move the coil closer to the main power contactor (before the branch points for the pump and fan circuit branches.)
Also, I don't see any indicator lights for switch position, or an element firing light (in parallel with the element.) Switch indicator lights allow you to determine the state of the system at a glace, without having to discern the position of each switch. Switch indicators are most easily (and with less panel space) implemented with lighted switches. An element firing lamp allows you to determine if your SSR has failed, or temporarily latched (due to overheating) in the "On" mode. The "firing" LED on your PID won't tell you if the SSR is actually switching (nor will the LED on the SSR, for that matter.)
Finally, I would run the pump and fan from the same branch using a single 10A fuse, unless your fan requires more than a couple of amps.
Brew on
