Originally Posted by caskconditioned
What's the difference between an SSR and SSRD? My understanding is that an SSRD contains two independed SSRs in one chassis. Could you control two heating elements using the same SSR or is it more to kill both legs of the 240?
Reason I ask is that I'm a bit confused on the electrical aspect. Say I have a heating element in my HLT (240V 5500w) and want to control it via an SSR. But when the SSR is off - I don't want any power going to the element. Will a standard SSR do that? Or is there always 1 hot to the element even if the SSR is off? I guess another way of asking the same question, if I use a standard SSR and it's off - will the heating element still be partially heating? Sorry for such a newbie questions.
The SSR will only cut ONE leg. Your element will not be heating, but there will still be current at the element.
I decided to use a 30A DPST switch to cut BOTH hots for this reason. Also, the DPST switch allows me to cut power to the element no matter what my PID is commanding. As stated in this thread, the DPST switch cuts power to the SSR and it cuts the other leg that goes directly to the outlet.
It is much cheaper than buying an SSRD AND it allows you to cut power to the element NO MATTER what the PID commands.
By doing this I can leave my PID powered, simply TURN OFF my element 100% dead with the DPST switch and use the PID to monitor cooling when I am chilling the wort.
Many of these questions are answered previously in this thread.