I have no background in HVAC either, but I bought a lot of the components for my rig from a guy that did and he was a huge help (user on here also). The hot surface modules I have have interchangeable tabs to control the number of retrys and ignition trial time in the event of a misfire or flame blowout, but as far as I know, the prepurge time is not negotiable so to speak. You may want to read through this thread
It has been a while since I looked at it, and I think the ignition system mentioned is a hot spark (still with flame rectification and much along the same lines as hsi) I do not know the prepurge time for this model. Nevertheless, there is a ton of good information in the thread from guys that know a hell of a lot more about this than me. That being said, I feel like I have encountered just about every problem imaginable in the process of setting up my system and along the way I have learned quite a bit about troubleshooting them and I am happy to help however I can.
Now....hot surface and hot spark are certainly NOT the cheapest way to go about automating a burner in my experience. I think the vr8200 valves with standing pilot are cheapest, but don't have flame rectification. For me flame rectification was big because I brew outside and am pretty sure my homeowners policy doesn't cover homebrew related explosions....cheers and hope you figure it out...wnc