Instructables

How to build a smoker temp control system like the bbq guru and such?

I would like to build something to keep my wood fired smoker at a constant temp by a forced air fan and dont want to spend 300 for a guru1

rod_c4 years ago
Re-design has missed the point a little bit & got it the wrong way round. Most smokers control hte temp by resrticting the airflow. So you want the fan to kick in when the temp drops & you want the upper temp controlled by the low air flow with the fan not operating.

This guy www.geekwithfire.com/ is a very talented guy at this very task, well worth a look.
Re-design rod_c2 years ago
I might have stated it backwards at that.
Re-design5 years ago
Connect a high temp thermostat to a relay. The relay controls the fan. When it gets too hot the fan turns on until the temp goes down. It will take some fiddeling to get it set right because it's going to continue to cool down even after the fan quits. If the fan is to powerful it might put out your smoke. If it's too small it might just feed your fire and make it hotter. You might consider making a remote controlled vent instead.
could you use an oven thermostat and hook up to a fan to get the control needed?
If it works on the same voltage.
bbq4usguys3 years ago
So has anyone came up with a solution. I once had a smoker that used a specific Honeywell Thermostat to control the exhaust fan. The thermostat was energized until the temperature was reached. At that point the circuit to the fan de-energized until the smoker's temp dropped below the controls setting. Temps increased as more air pass through the system once the controller re-energized the fan circuit.

This control would maintain a 3 degree range. All I need is figuring out which thermostat to buy.

I've been wanting to do a similar project for the oil drum braai that I built last year. Have a look on the web/wikipedia for PID controllers (Proportional Integral Derivative controllers) which I think would be great for this sort of application and should be able to give you better control than a simple on/off switch if you set it up right.

You'll need some sort of temperature sensor to interface to the PID and a circuit for the output of the PID to control the fan speed.

PID'sare straightforward to implement in either hardware or software (you can make them out of mechanical components if you are so inclined) but they need to be tuned to work correctly for a given application. I'm interested in making a PIC microcontroller based project but you could also use simple op amp circuits with variable resistors to do the tuning.

I'm not an expert in PID's but your post struck a chord with something I'm interested in. I hope this points you in a useful direction and good luck with your project.