3500w boil kettle controller ?'s

Hey guys, I have a few questions about my potential setup. First off let me bore you with some details. I have brewed a bunch of extract with grains batches and want to get an all grain setup going. I live in a condo so brewing outdoors is not an option. I will brew 5gall batches only. I have a 240v 20amp outlet readily available.

Ive recently accuired a 3500w ulwd element and from what ive read should bring 7+ gallons to boil in a fairly reasonable amount of time. My question (and maybe this is the dumb one and ive answered it myself) is if this is ok to use on a 20amp curcuit. 3500w/220v=15.9 amps?

For a controller I want to use this Pid with SSR output controls and 2 SSR's 25amp.
http://www.auberins.com/index.php?main_page=product_info&cPath=1&products_id=3

http://www.auberins.com/index.php?main_page=product_info&cPath=2&products_id=9

Ive found this diagram and wanted some opinons on it.

http://good-times.webshots.com/photo/2111607970092427663pltgSA

I would like to add a DPST but not sure where it would fall into place. Before or after the SSR's?

Any help would be appreciated

Yep, that's my diagram... I haven't built my system yet, but I put that graphic together based on other builds on here. I'd put the switch before the SSR's... right after your power cord comes into the box. I'd also go up to the 40A SSR's. It seems overkill, but the 40A SSR's will run much cooler than the 25's and it also allows you a little more wiggle room in case you decide to move up to a 4500 or even 5500W element later on.

Thanks for the work on the diagram! I had a pretty good idea of how everthing came together but the visual really helped. I was thinking I should use the 40amp SSR's, for that very reason, but I didnt know if there was a downside to using them with the 3500w element.

Also, is this the thermocouple that I should use?
http://www.auberins.com/index.php?main_page=product_info&cPath=3&products_id=2

If you switch the power when it comes right into the box you will not have the PID on and able to read temps. So I'd switch the main power and add a switch after the SSR to turn elements off while still reading the PID. It also provides you with a safer system since SSR's can fail leaving power on the element. Switches are pretty cheap, worth the insurance.

That makes sense but brings me to more ?'s (sorry). What would be a better option for the switches? Heavy duty DPST toggle switches that can handle 20 or more amps or a lower rated switch with contactors?

Thank you for the help!!

I would use a contactor. I would wire the contactor ahead of everything but the PID. That way, when the control panel is plugged in, the PID will be on but all the power beyond the contactor will be off until you turn it on. You can monitor temps or set up your PID with the elements off. You could also switch your pid if so inclined.
Is your 20 amp 240 vac outlet 4 prong or 3 prong? If 3 prong, you will need a contactor with a 240 vac coil. See below
http://www.cshincorporated.com/product_info.php/products_id/3232
If 4 prong, you can use a contactor with a 120 vac coil
http://www.auberins.com/index.php?main_page=product_info&cPath=2&products_id=129
The contactors have male quick connects that you can use to wire the switch to the coil and to wire the PID. Very clean and very simple. Some would disagree, but with the contactor as a mechanical shut off for the element, you could safely use one SSR to control the element. The mechanical shut off is very convenient to prevent boil overs.
I would also buy a power cord with a GFI unless your 20 amp, 240 vac breaker is a GFI breaker.

Thanks guys! Between your help, the forum and electricbrewery.com I think I've got a good layout for my needs. I've started to order parts and will post pics of my progress.
Thanks again
Aloha!