I'm building a gravity fed smoker and I'm thinking about trying a fan instead of a blower to create a custom attachment. My impression is that blowers typically create more pressure than a similar sized fan. What are the important specs when choosing a fan or blower? Is this doable? If it won't work I'll focus on using a blower.
Fan Instead of Blower?
- Thread starter MichaelJF
- Start date
Hopefully, SteveCK will have some input on this topic. He's been doing some great work with using a fan in his MicroDamper set up, which seems to be doing rather well.
Andy Snider
TVWBB Fan
Most 12V fans will work, up to an amp or 2 (your power supply will be the first limit, then the PCB traces - can't remember what they're rated for off the top of my head).
Fans are usually more efficient moving air w/o restriction, centrifugal blowers can overcome more static pressure (like pushing air through charcoal/meat/small outlet openings).
The HM-recommended delta will put my Keg on runaway fire at anything over about 40%. You'll probably be fine with a fan, depending on your pit size.
Fans are usually more efficient moving air w/o restriction, centrifugal blowers can overcome more static pressure (like pushing air through charcoal/meat/small outlet openings).
The HM-recommended delta will put my Keg on runaway fire at anything over about 40%. You'll probably be fine with a fan, depending on your pit size.
Well put, young Andy!
Remember that a BBQ needs air, and if you run it "old school" it's natural draft. I don't think "static pressure" really enters into the equation for stoking a fire (as proven in many threads here), of course, depending on your smoker size. You need to add oxygen, and depending on your setup, it really doesn't require much "fan" air to make it so. I think it's more about the PID settings with the fan/blower setup you have. With a fan, the settings may deviate a bit from the norm (of course, I could be wrong).
I think SteveCK has busted this myth with his MicroDamper design.
I'm not a ventilation engineer, but I did play one on TV.
I use a blower, but I dialed it down a bit with my design, just for the fact that with the Delta 6.7 CFM blower, I had to dial down to almost 20% max with my 18" WSM (and it's a leaky bastard). The Adapt-a-Damper uses a cheaper 5.7 CFM blower, but even cheaper would be a fan setup such as SteveCK suggests to run even the most inefficient grills.
With a Kamado style grill, I would suggest a setup to run damper over fan, and have the fan turn on only if needed.
Now, of course, if you have a beast, like a 3 tier Pro Q/WSM style smoker like someone posted here most recently, then yes, you may need a blower, and a large blower at that, depending on what size orifice you're sending the air through.
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SteveCK
TVWBB Pro
The important specs when choosing a fan are it's CFM output and static pressure capabilities. With all the testing and research I've committed while developing the MicroDamper I have zeroed in on using a 10CFM fan at 10mmAq to run everything from a kamado up to a UDS. I have found that I can use a lesser fan for the kamado, but response times are slow. The Delta EFB0412VHD, I find does an excellent job on both pits. PID settings and fan speed setting will differ between using a blower vs a fan. As was mentioned further up, a centrifigul blower can push with a higher static pressure. That's fine an all, but they are overkill. Blowers are designed to move dirty air or air through very restrictive ducting. A kamado, kettle, UDS, etc runs off of clean air and pushes through a relatively open space with some minor choking points at intake and exhaust.
OP, feel free to shoot me an email if you choose to go the fan route and would like to discuss further. I'm always talking to a handful of people on this forum about something, why not make it another?
OP, feel free to shoot me an email if you choose to go the fan route and would like to discuss further. I'm always talking to a handful of people on this forum about something, why not make it another?
SteveCK
TVWBB Pro
When your pit is run manually, "static pressure" is created by the fire itself. Assuming it has a large enough intake hole and exhaust hole it will eventually find equilibrium by pulling/pushing a certain CFM to maintain the fire. When you start to introduce a device to control air flow you know have to "think like the fire", you have to choose a fan which provides the CFM at an appropriate static pressure to maintain the fire. For example imagine a UDS with a big hole on the size to fit a 80mm fan. You can mount that fan there, but if it doens't have any static pressure capabilities it won't be able to push air all the way up and through the exhaust. Basically your fan will spin but nothing happens.
Told you. Thanks Steve.
I wonder (if it hasn't been discussed before?) about the semi-automatic mode...where on a kamado (or other grill I guess) that you set the manual openings to a bit below your target and use the servo/fan to assist the remainder. For example, if I want to set a 280f setpoint, I know on my smoker how to get set around 230-250f manually and I have the fan/servo just assist the last +/- 40f. I use to do it that way before on my simple auber controller because I was guaranteed if anything went wrong that the smoker would hold the lower manual setpoint and the fan was only used for final setpoint. I would assume that in semi-auto mode that the fan wouldn't need to be that strong?