Dual Blowers


 
J

JCarney

New member
I couldn't find any information on here so here goes. I am trying to run two blowers from the same output. My offset smoker was not pushing enough air with a single blower (which could be a whole other thread) so I decided to run two blowers by just splitting the output.

Here is what I am running. Yes, both are the exact type.

http://www.digikey.com/product-search/en?KeyWords=259-1367-ND

I am running HeaterMeter 4.2 with a RPi

When it goes from 0% to any value it reboots the HM.
If I plug the second fan into the y adapter I made after the fan is spinning, it works fine and powers both from 1% to 100%
If I plug both straight in after I have set the fan speed above 0% it works great.
It is really only going from 0% to anything else with both fans plugged in that is causing the failure.

I am assuming there is a spike from 0% to greater than 0% that is possibly overloading the board.

Thanks for the help.
 
The stock HM fan shows an input current of 0.2A, while each of your fans have an input current of 0.7A.

You'll probably need to beef up your 12v power supply to something that can supply at least 2.5A or 3A
 
Edited: i just clicked on your link. Holy smokes, your trying to run two 30cfm blowers. I run a 28cfm on my uds at a max of 30%, using a minimum of 1.2amp adapter. Anything smaller and will make the hm restart
 
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The HM does a little bump start for the blower when it turns on to get it spinning, then it slows down to whatever speed (say 1%), this is to aid the blower in getting rolling at low speeds. I would guess with 2 whopper blowers the current draw to start up the blowers would be a bit, but would think a 2A PS should do it.... but not all power supplies are equal, so maybe try another supply, different brand and/or larger amperage...

On another note, are you SURE you need both those blowers? When you ran with a single blower was it a single one of those big blowers or the stock HM blower? The stock blower has around 6CFM flow VS 30CFM for ONE of those, so 5 times as much, with two its 10 times as much air flow. If you haven't tried running just one of those large blowers I would give that a shot....
 
I have run multiple smokes with a single larger blower and it was very difficult to keep the heat high enough. Almost any lid opening takes adding lit coals to get the temperature back up. I also have added firebrick to the pit to help. The smoker is sealed well enough that when the fan isn't running it will bring the temp down.

The higher power supply will be here tomorrow. I will try it then. I will update here with the results.

Thanks for all the help.
 
You said this is an offset smoker? How do you have the fan mounted, where is the air going, is it hitting the fire directly or maybe passing it by? Try mounting the fan so it blows more directly on the fire? Pushing more air that doesn't directly hit the fire may actually cool your pit down due to pumping high volumes of cool air into the pit, the more you turn over the air in the pit the more heat you lose.
 
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I think knowing the size of the offset would help.

I really also think you are using a blower that is way to big or you have restricted the inflow of the blower way to much. My 28cfm is like a hair dryer at 100% and will actually make the temperature go down, as blows all the hot air out of the UDS and wont reach setpoint. I have to run mine with a max of about 8 to 10cfm, which is about 30%.

Are you able to control the offset without a blower? when the inlet is all the way open, does the temperature go up?

To set the HM on your smoker try the following

1. run without the blower and get the temperature to a stable 230.
2.add the blower using manual mode start the blower at 5% and observe the temperature. if you see no movement then raise the blower percentage, until you see movement in the temperature. If you see it rise then slowly raise the blower percentage until you see the temperature go down. At that point, that's the point that you are blower the hot air out of the smoker and the cool air is hitting the pit probe. You then, lower the blower percentage until you see the temperature stabilizes and begins to raise again.

Once, it begins to raise again, that's about the maximum blower percentage you will ever need. Lets say you find that the max is 50%, then the biggest blower you would need would be around 15cfm, but it would be best to get a something between 15 and 20.

Also, make sure the pit probe is mounted at either grate level or 1 inch below where you actually put the food.
 
I can control it well manually with just the dampers. I have tried the stock fan, a single of those I posted and neither worked great. I will post pictures tonight
 
When you are running the pit with the dampers how much air is flowing out of the stack? I would think less than when you have a 30CFM fan blowing like crazy? I'm thinking you need to make that air stoke the fire more rather than just pumping air through your pit... pics will help a lot...
 
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RalphTrimble said:
When you are running the pit with the dampers how much air is flowing out of the stack? I would think less than when you have a 30CFM fan blowing like crazy? I'm thinking you need to make that air stoke the fire more rather than just pumping air through your pit... pics will help a lot...
Click to expand...

You stoled my question, lol. I was thinking the same. When I have my 28cfm blowing at 100%, its literally a hair dryer blast of air, in fact there is so much air it goes out all around the lid, and outlet or any other hole or crack i have not plugged up tightly.

I'm almost positive, he experiences the same as what I experience, when its at 100%. All the hot air is blown out and it cools the pit probe. If you are able to control your smoker via the dampers, then a blower of probably in the 8 and 15cfm range.
 
After seiing you pics, i think i see a problem. Your inlet which looks like half inch or 3/4, may be to small. Also, you probably dont need the piping inside the box, it looks like you are blowering down from the top of the basket. You would be better to just let the blower blow directly into the fire basket and remove the baffle inside.
 
I don't run an offset smoker, but I would think you want to leave the stack open wide unless you need to reduce flow to tamp down overshoot...

That setup you have there looks like a prime candidate for my "air burner" design... It's an air delivery system that goes under your fire basket that kinda looks like a gas burner, but it pumps in air instead. Just a network of pipes with small holes in it that shoot jets of air right onto your fire, it really stokes and controls a fire well... It's hard to implement in a Kamado but great on a bullet smoker or something with a fire box with space under it like this offset. Check out the thread I linked or this thread for more details....
 
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