Convection oven fan

[Rockydoc]

The PROBLEM:
My convection toaster oven plugs into the PID to get its power. The PID controls the temperature in my toaster oven by turning the power to the oven on and off as the temperature probe inside the oven detects the temp cycling up and down over a narrow range.

The fan in the oven is what makes it a convection oven. The oven must be turned on for the fan to run. The PID cycles the oven off/on so quickly that the fan can't get up to speed before the power is cycled off again. The fan is therefore not on long enough for it to really be a convection oven.

The SOLUTION:
Create an independent power supply for the FAN. This would require a power cord with plug and switch. The problem with this solution is: I don't know how to do this. I suppose I could just muddle through and try to figure it out as I go along. Or I could seek the advice of my favorite group of advisors.

 

[popper]

Fan is an ac unit (more than likely and PWM will burn it out). Fan SHOULD be wired to ac through the timer. I just connected my PID to the heating elements, and normal ac to the rest of the unit. Two ac cords, one for my external PID power and one for the rest of the oven. My oven is at least ten yrs old, left over from the kitchen. Newer ones maybe different, just depends. Mine doesn't have any digital controls.

 

[Rockydoc]

Mine doesn't have digital controls either. That sounds like a better solution than to one I envisioned. See, there was good reason to post this thread.


I should therefore find the wires that go to the heating elements and route a separate wire from there to the PID. Only the heating elements would cycle on/off.

 

[Rick]

My convection oven is probably 20 years old, no digital controls. The heating element cycles on and off to maintain temp, fan runs continuous as long as the timer has the oven running. Pilot light on the front indicates if the heating elements are running cycling on & off, fan is constantly circulating the hot air.

 

[Ian]

Yep, fish out the element wires and wire them directly to your SSR. Plug the oven in a standard outlet as normal to run fan and all other functions.

 

[Rockydoc]

Yep, fish out the element wires and wire them directly to your SSR. Plug the oven in a standard outlet as normal to run fan and all other functions.

Ian, that sounds like a permanent connection to my PID. I use the same PID for my RCBS Pro Melt as well as the toaster oven. I have dedicated thermocouples on each that plug into a jack on the PID.

 

[popper]

A plug for PID power (into PID box - connected to heating elements only) and a separate one for timer/fan (to wall power).

 

[Rockydoc]

My convection oven is probably 20 years old, no digital controls. The heating element cycles on and off to maintain temp, fan runs continuous as long as the timer has the oven running. Pilot light on the front indicates if the heating elements are running cycling on & off, fan is constantly circulating the hot air.

This is true as long as power is going to the fan. It gets it's power through the power cord, which in my case is plugged into the PID which is cycling on/off to maintain a constant temp in the oven. So the fan cycles on off with the power supply but it's spool up time is longer than the PID cycle time so it never stays on long enough to do it's job.

 

[Rick]

This is true as long as power is going to the fan. It gets it's power through the power cord, which in my case is plugged into the PID which is cycling on/off to maintain a constant temp in the oven. So the fan cycles on off with the power supply but it's spool up time is longer than the PID cycle time so it never stays on long enough to do it's job.

True, so simply wire the fan to where the PID gets it's power. Problem solved, fan will run as long as it's plugged in and the PID can still cycle the heating element.

 

[358156 hp]

Ians talking about running one cord for the fan that can be plugged into a wall outlet for full time fan function while the power to the heating element is run through the PID. Alternately, you could build an additional circuit with a plug socket into the PID that runs off of full-time power from the power cord. This should be switched through the main power switch so you can turn off all power when needed by simply shutting off the main power switch. This would make it impossible to leave one circuit live unintentionally. This should be pretty simple to do if your PID case is large enough.

ETA: Rick beat me to the point. I took too long to compose my thoughts. Dang it....