Automatic draft control "flapper"

smootz · Posted: Wed Nov 30 16 9:33 am Post subject: Automatic draft control "flapper"

A few years ago I saw a very simple but very effective automatic draft control on a large propane tank based stick burner. Unfortunately it was at a bbq restaurant and I could not see or obtain much information.

The whole setup was homemade. It consisted of some sort of oven thermometer wired to a solenoid actuator. The actuator pulled a wire that opened and closed a "flap" style vent on the fire box.

It was super simple but worked very well. I watched it open and close several times. BTW - the BBQ was great!

It would be easily fabricated if i could find a thermostat that would work within smoker temp ranges to send a signal to the solenoid.

Is there a reason why blowers are typically used instead of automatic dampers?
_________________
150 gallon vertical
propane pig
180 RF

biker.chef

k.a.m. · Posted: Wed Nov 30 16 7:36 pm Post subject:

On typical draft controllers blowers are used on the intake to force air into the firebox or stop the flow completely. The flapper you're describing sounds like what J&R Oylers use to control the temps in their rotisseries.
_________________
Always remember slow and steady wins the race.

Hybrid Cooker

smootz · Posted: Thu Dec 01 16 3:39 am Post subject:

I briefly looked into this a few years back. The system is super simple and could be easily fabricated if I could find the right kind of thermostat control. It may be as simple as the thermostat from an old kitchen oven. All I need is something that will trip a solenoid actuator. Just "on-off". Trap door is either open or closed, nothing variable or progressive.
_________________
150 gallon vertical
propane pig
180 RF

animal · BBQ Pro Joined: 05 Nov 2007 Posts: 935 Location: Wisconsin

Something like this

http://www.maverickhousewares.com/ttt-01-tip-top-temp/
_________________
New Braunfels Offset
Smoke Hollow #5
Lang 48 D
Acorn Komado
And a couple of Weber kettles

smootz · Posted: Thu Dec 01 16 7:20 am Post subject:

biker.chef · Posted: Thu Dec 01 16 7:26 am Post subject:

A BBQ Guru or a PID off Ebay would do the job nicely.
More bucks it would give you a set it and forget it controler.
_________________
-------
Every Day, Thousands Of Innocent Plants Are Killed By Vegetarians.
Help End The Violence.
EAT BACON

smootz · Posted: Thu Dec 01 16 8:49 am Post subject:

If everyone is using blowers instead of flappers there must be a reason. I need to lurk for a while and get educated on PID. (Not sure what that stands for).
_________________
150 gallon vertical
propane pig
180 RF

jess · Posted: Thu Dec 01 16 6:38 pm Post subject:

proportional-integral - derivative controller..
And with that said I bet most people still do not
know what that means... Smile

smootz · Posted: Fri Dec 02 16 1:56 am Post subject:

k.a.m. · Posted: Fri Dec 02 16 3:52 am Post subject:

This one has been getting some good reviews on the competition trail. I watched this business grow from a go fund me account.
http://theperfectdraft.com/
_________________
Always remember slow and steady wins the race.

Hybrid Cooker

biker.chef · Posted: Fri Dec 02 16 4:03 am Post subject:

I've not used a guru but I don't think it is variable speed.
My controller will pulse the fan. Short bursts of on/off.

I did a posting a few years ago about a DYI PID. I can try to
find it. But if your not familiar with wiring your best sticking
with with a commercial solution.
The advantage of an electronic controller is that that homes in on the
desired temperature. As the smoker gets to set temperature the controller
will start pulsing the fan so it doesn't over shoot the temp.
As it senses the smoker is cooling off it will start the fan again.
It "learns" over time and keeps the smoker at constant temperature.

A mechanical thermostat will keep the air flow open until the
smoker is at temperature. The fire is still hot so the temp will rise well
past the desired temperature. It will close down until the smoker has
cooled past the turn on temperature.
So the problem is you will get spikes and dips in temperatures
_________________
-------
Every Day, Thousands Of Innocent Plants Are Killed By Vegetarians.
Help End The Violence.
EAT BACON

PaleAle · Posted: Fri Dec 02 16 6:45 am Post subject:

Depends on your DIY skills you can look into heater meter. I love mine!!!!

RodinBangkok · Posted: Fri Dec 02 16 7:29 pm Post subject:

Take a look at using an Arduino controller with a servo to control a butterfly valve on your exhaust, it can also easily control the intake fan via PID software. Probably won't cost you more than $50 bucks if you have some tinkering skills.
_________________
Rod

mbellot · Posted: Fri Dec 02 16 11:07 pm Post subject:

I've used one from Auber with good success on a couple different smokers/grills. I even played with it and some homebrew electronics (SSR) to make a crockpot sous vide setup.

The one thing I found with the Auber (maybe all PID controllers, not sure) is that you are better off getting close to your target temperature (50F or so) before engaging the control, otherwise the blower will tend to ramp the fire up too high and you end up with an overshoot that risks snuffing your fire when it's trying to bring the temperature back down.

biker.chef · Posted: Fri Dec 02 16 11:35 pm Post subject:

smootz · Posted: Sat Dec 03 16 11:31 pm Post subject: