Grain dryer

[Wjg]

I have an opico 580s that won't hold gas pressure steady we have it set at 25psi but every 30 seconds pressure rises to 50 for about 10 seconds then drops back down to 25!! It keeps doing that for the whole cycle.
Does anyone have any idea whats going on?

 

[v8willy]

Some models have a twin jet setup, say you have it set to 200, so high jet comes on & heat rises to about 210 then it closes & the low jet keeps going, temp falls slowly to 190 & the high jet kicks in again, gas pressure rises & falls as needed.