Hey! Just to give an update to you guys.
I just conducted a few tests using Peltier (the type that I am using I mentioned previously) to heat up my chamber and it is possible to reach 50 degrees C in my test chamber (volume is currently 10x10x10 cm). I placed heatsinks on both sides (hot and cold side) and fans on top. The thermal lag that people mentioned actually does not seem to be that bad (my temperature range is +-2 degree C). Using Grove humidity and temperature sensor http://wiki.seeedstudio.com/Grove-Tempe ... ensor_Pro/
, I measured around maximum 1 degree C increase once I turned off the supply to Peltier and fans, assuming that you insulate the chamber properly. After that, the temperature stabilizes and drops down very slowly, because I still have a few leaks on my prototype chamber.
In my opinion, I do not seem to need to use a PWM signal and SSR (contact relay is sufficient) to regulate the temperature as I just need to keep the temperature in that range for a few months. However, if the temperature range is pretty small and keeps changing quickly, having one would certainly be helpful I think. I hope this helps!