Overpowered Heater and Update on my Glycol Chiller

So I’ve finally got BrewPi running on my Glycol Chiller build; I attached a second temperature probe onto the Glycol Jacket to give BrewPi a “Fridge Sensor” for cooling. The cooling function seems to be working perfectly now. But my problem is this: I want to also be able to heat my 50L keg up to 50C for doing sour mashes and as such I’ll have to use a pretty powerful heater attached to the bottom of the keg. The heater that I found for this was some ~150W stainless steel heating boards and they seem to be able to apply very powerful heat; so powerful that I’m worrying if I connect them to brewPi the heater cycle will get them really hot and will locally overheat the beer/the stuff holding them because when I first connected everything I left the heater off to see how long the cycles were and they started at ~10-15m which seemed tuned for the space heater in a fridge method but it might melt some attachment methods for my purposes…

I’m wondering if there’s some hidden setting where I could apply a Max Heater Time to keep the heater from staying on the whole time until the beer temperature rises? Or is it possible to attach a second “Fridge” temp probe to give the heating cycle more immediate feedback on its temperature changes?

Also it seemed like brewPi was trying to turn on the heater to heat up after a cooling cycle; is there a ways to reduce the Min Cooling Time? Or extend the lockout on switching control from cooling to heating?

It sounds to me like most of your problems would be solved by moving your fridge sensor closer to the heater.

The settings you want to change can only be modified by recompiling the software yourself.

Your setup sounds very similar to mine. My 50L stainless fermenter has a glycol jacket, using a Cornelius Maxi flash chiller, and a heater pad of similar power: http://www.ebay.co.uk/itm/271578114098

I think the issue is as much one of design as it is of BrewPi. High powered localized direct heating is probably not the best idea. The only way I can see of using this type of heating with BrewPi is to use the forthcoming PWM support to hold back the heater. I am not so worried about overheating the whole batch, as I think that shouldn’t happen, but I am concerned about overheating the yeast cake. My heater is on the base.

I am coming to the conclusion that a a soil warming cable wrapped around the outside or another low watt density heater might be a better solution, BrewPi or not.