Why is a PID needed

[smokinbird89]

Why would I need a PID when a simple thermostat could regulate the temp inside the oven. I have an old Grieve oven that I am going to put elements in instead of using the 3 phase motor and coils. Trying to save money any where I can. Please help.

[GeneNewcomb]

I used to use a generic home oven thermostat and found that the temp might drop from 450 to 435 before the burners would come back on. The PIDs are more than you need but I don't know of an inbetween alternative.
Gene

[smokinbird89]

Thanks for the info, I am still trying to figure out how many elements I might need. The inside measurements are 67" tall x 72" wide x 33" deep. I think I saw a formula on here for that but not sure where it is yet.

[mikmj]

Originally Posted by smokinbird89

Thanks for the info, I am still trying to figure out how many elements I might need. The inside measurements are 67" tall x 72" wide x 33" deep. I think I saw a formula on here for that but not sure where it is yet.

Go here BTU Calculator

[JTW37]

The limit on elements is how much breaker you have and what amp service you have. Most are figured with 50 amp breakers and 100 amp service. 12000 watts total will = 50 amps. So when you find out how much you can use then total all the watts of your estimated elements and divide by 220 or 240, whichever yours is, and that will give you total amps needed. Just don't max out your breaker rate, try to stay a little under, like 40 amps.

12000/240=50 amps

My oven is 6x3x3 with 8150 watts total = 34 amps. Also PID is a good investment. Keeps oven temps steady once it gets trained.

[PhredAre]

Your question " why is a PID needed?" is simple to answer, its not. There are numerous Temperature controllers available that are compatible with SSRs or Contactors. Most use "k" type (etc) themocouples and will control with a fairly tight control range. The part that this dosn't address is the expense. It appears that there is not a cost advantage by not purchasing a PID. It seems that temp. controllers, cost wise, are about the same money as a PID. Just buy a PID and use it as a temperature controller, keep it simple. Fred