[ed_denu]

If you are planning on using (4) 3100 watt elements you are going to be drawing about 52 amps. I have a Fotek SSR and I know they make these in up to 75 amp units.

If you are looking to use (2) 40 amp SSR's then you need to look closely at the specifications for the PID and SSR's you are planning to use. Specifically, on the PID I use, the output driving contacts are rated at 8 VDC and 40ma. This means that the PID outputs a DC voltage of 8 volts used to drive an SSR. However it is also limited to 40ma. The 40 amp Fotek SSR is rated to operate on 3-32 VDC and consumes 20ma. So you can see that the PID output of 8 VDC and 40ma load will match to the SSR I am using. However if I wanted to use (2) 40 amp SSR's, with (2) elements each, then I will be at the 40ma limit of the PID. Might work for awhile but you probably run the risk of destroying the PID.

You need to look closely at the specifications of the PID and SSR(s) to determine if these devices will work correctly together. If you want to post specific device information I'm sure someone would be able to help.

Keep in mind that a 52 Amp load will require a 60 Amp circuit using #6 wire or greater.

As for the fan, I don't have specific air movement calculations available. I believe someone posted these calculations recently. Recirculating the air from top to bottom via ducting is what I do and seems to work well. Other options would be a fan within the oven.