Hot Suface Ignition Setup ?

I have a PID controlling an old school low pressure gas valve and pilot
with thermocouple. I'm thinking of replacing it with a hot surface ignition
(hsi) system. I use it to direct fire the mash and in manual for the boil; I
BIAB. When maintaining mash temps; the PID will modulate the gas valve
once or twice a minute. How reliable would a hsi system be in this setup?
Which component models would be preferable?

I use HSI on my rig, and I like it. Time from call for flame to flame is about 1 minute with my modules. It goes through a prepurge and then ignitor warm-up sequence before it opens the valve. The amount of heat lost in said minute is pretty negligible in my opinion, and I like the idea of flame rectification.

The modules I use are honeywell s8910u. They are really pretty simple, you supply 24v and 120v to the module, and it then sends 24v to the valve and 120v to the igniter upon call for heat. The modules are available on ebay for 50 bucks or so. I will take some pictures of the modules, valves and ignitors tomorrow if you are interested (my stand is still in progress in my shop at work, but wet tests have proven the hsi to be satisfactory)

Thanks for the info wncbrewer, i obviously don't have a hvac background. I wasn't aware the prepurge (makes sense now) is managed by the module; I thought the control board took care of that. Is their a module available which only handles the ignition, gas valve and flame rectification? That is what I need. If I can't find one, I think might build one? Are current oem modules secured with resin or can they be tampered with? My wallet is getting nervous.

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

https://www.homebrewtalk.com/f51/gas-temperature-control-dummies-116632/

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

Thanks for the link, I was sure others have been down this path. I brew in my garage, so flame rectification is a must. As home owner's for insurance, I have a family member in that racket. She has seen my operation and said no insurance company would ever cover anything due to a home-built brewing apparatus. That being said, I will carry on. The motivation for all of this is, I enjoy gadgets and because I disconnect my gas supply line between brew sessions. It takes a few minutes to purge the pilot supply line when re-lighting. Thanks again.