2 element 2 pump single PID wiring help

[schach23]

Hey guys,

Found these diagrams which would allow me to run my 3 vessel eherms system.

https://www.homebrewtalk.com/showthread.php?t=221403 post #6

and from PJ's list of diagrams thread:


Which diagram would be the "best"? Any updated guidance? These diagrams are from january 2011

Scott

 

[doug293cz]

The one with the contactors. The 3PDT switch called out on the direct switching diagram (Grainger PN 2TNZ7) is only rated for 9A @ 240V, and has no off position.

Brew on

 

[schach23]

Hey I think you are referencing this diagram which I like as well for the most part except the selector switch for the elements. The way I read it is that either element is on but i would like a center off. Could I substitute the Auber SW3?
http://www.auberins.com/index.php?main_page=product_info&products_id=235

 

[doug293cz]

Hey I think you are referencing this diagram which I like as well for the most part except the selector switch for the elements. The way I read it is that either element is on but i would like a center off. Could I substitute the Auber SW3?
http://www.auberins.com/index.php?main_page=product_info&products_id=235

You can absolutely substitute an SW3 (center off) for the two position selector switch. In fact you should do so, as otherwise there is no way to disconnect power to both elements. Since the most common failure mode for SSR's is "on", you can't depend on an SSR to act as a disconnect.

Brew on

 

[doug293cz]

Not sure if you've seen this variation of what you are building. I like the third contactor being used to control all power to the system.

The main power contactor also gives you the option to wire up a "safe start" circuit, which requires everything to be off before main power can be turned on, or use an EPO switch that doesn't depend on tripping the GFCI in order to cut power.



Brew on

 

[schach23]

Not sure if you've seen this variation of what you are building. I like the third contactor being used to control all power to the system.

The main power contactor also gives you the option to wire up a "safe start" circuit, which requires everything to be off before main power can be turned on, or use an EPO switch that doesn't depend on tripping the GFCI in order to cut power.

View attachment 321905

Brew on

I did find that just the other day. I like it better as well. Seems to have a better safety profile. I like the idea of a master on/off switch. Appreciate your help! Cheers!

Scott