First smoke with HM4, results and questions

My results HM4, WSM 22.5

Here are the results and comments of my first Pork Butt smoke as well as the first time using the HM4
This post is also in the Graph thread, but I figured that it would be better here for comments and leave that thread for graphs only

Smoker was started up around 7:30 PM to test HM4. Full of coals with a hole in the center to dump about 30 hot coals into. Using Kingsford Original.
Stacked 2 coal grates, the stock grate that sits on the bolt heads from the legs. The other is the exact inside diameter as the coal ring so I put that on top of the standard coal grate. My thinking was I would not have as much coal drop through due to smaller holes.

2 bottom vents closed, top open about 0.25, Fan mounted in bowl and toggle bolted in place, open 100%. Water pan foiled and filled with hot water.

WSM 22.5 has nomex gaskets and probe grommet hole.

Smoker came up to temperature (225) and held it nicely about an hour later. So I figured I would prepare the butt.

8lb 2oz, boneless Swift Premium pork butt from Costco, tied up the butt, rubbed with Memphis dust. Let sit at room temperature for about an hour, rubbed again and put in smoker at 10 PM

Decided early on after having read about the stall, that I would power through it and give the HM a run for its money.

Settings were:
B: 4
P: 3
I: .005
D: 5

Smoke wood:
9 oz Cherry
10 oz Apple
4 oz Hickory

How it went:
07:30 PM started smoker, full load of coal, small divot in center for about 30 light coals, foiled pan, filled with hot water
09:30 PM added smoke wood
10:00 PM Put in butt fat cap down
01:30 AM temp down to 208, fan at 100% since 1:00 AM, stirred coal, butt at 130
07:00 AM temp down to 195, fan at 100% since 5:20 AM, added more coal, butt at 154
10:50 AM temp down to 215, fan at 100%, stirred coals, no room under grate, fill with ash, butt at 168
01:30 PM temp down to 215, fan at 100%, broke open smoker and removed ash which was all the way up to the grate so no air could flow under. Removed smaller grate. Added coal, butt at 168
01:50 PM smoker back up to 225, fan at 0 to 3%, butt at 168
02:30 PM still going, wondering if powering through the stall is smart or not, smoker at 225, fan at 9%, butt at 168
02:50 PM starting to wonder if food probe is not working, stuck butt with meat thermometer, it’s right on the money! Both at 168
03:00 PM WOW, finally hit 170! we’re moving now, well maybe, damn I’m hungry!
03:40 PM low temp (200) alarm went off, had to stir coal, went down to 197, Butt at 172
04:15 PM temp still dropping, lit a half chimney of coal and added as well as more unlit. So far have gone through about 30 lbs of coal
05:00 PM pit at 230, pushed pit temp up to 250, butt at 174
06:00 PM pit losing temp down to 190, fan at 100% stoked coals,
06:30 PM fan at 100%, opened top vent to 100%, opened 1 bottom vent to 100%, butt at 183
07:00 PM closed bottom vent to 50%, smoker at 260, butt at 187
08:00 PM butt at 195, tested with fork twisted 90 degrees meat pull apart nicely.
08:30 PM pulled and eating pulled pork, no time to rest it, I'm starving!


Questions/observations:
1 - Used PitDroid app.to monitor HM4. Set up alarms to monitor while I tried to sleep. Worked very well.
2 - Will not use the 2nd coal grate again, I think it caused ash to get stuck and not fall threw. Thoughts?
3 - ET-732 pit probe worked fine
4 - ET-732 food probe dropped out 4 or so times for seconds each time (Bryan posted a fix of soldering the shield to ground on connector)
5 - Having problems keeping steady temps. Should I change the PID settings?
6 - The fan blows across the coals, would it be better to have the fan blow under the coals? (saw a post where someone made an air distribution chamber for under the coal grate)
7 - Blue blower speed bar is neat, but what is the small grey line tell you?
8 - How can I hold temps like I see everyone else is able to?
9 - 30 lbs of Kingsford original seems like a lot?
10 - Butt seems very black instead of brown? But it tastes good, moist.
11 - Is foiling at 150 to 160 degrees the better way to go?
12 - Butt started at 8lb 2oz, finished at 4lb 14oz, during the stall/cook it lost about 3 lbs of moisture. Is that much weight loss normal?
13 - 22 hours to cook a butt, holly $hit, anybody else ever have one go that long?

Please let me know your thoughts on how I can improve the performance of the HM4?

Graphs:




Meat rubbed and ready to go:


Finished still on the grill:


Sliced to show smoke ring:




Thanks,
John

The small gray pip you see moving about on the fan speed percentage is the average fan speed.

It is surprising how many times your fan was running at 100% for a long time and the temperature continued to drop. That's either not enough ventilation or fuel. You may also want to increase the "Lid open detect" percentage because when it goes below 216F (assuming 4% of a 225F setpoint), the fan turns off for 4 minutes and that's not doing you any favors either. Those are all the yellow areas on the graph.

Bryan Mayland said:

The small gray pip you see moving about on the fan speed percentage is the average fan speed.

It is surprising how many times your fan was running at 100% for a long time and the temperature continued to drop. That's either not enough ventilation or fuel. You may also want to increase the "Lid open detect" percentage because when it goes below 216F (assuming 4% of a 225F setpoint), the fan turns off for 4 minutes and that's not doing you any favors either. Those are all the yellow areas on the graph.

Click to expand...

Thank for the info Bryan, the lid open is set at 6%, I'll up it. I manually did the open/close instead of using the lid open detect.

I had plenty of fuel, I think it's an air problem. The WSM is very tight with the nomex gaskets. I'm wondering if I should direct the air under the grate for the coals?

When I saw that the fan was running at 100% for some time I manually intervened and stoked the coals. I figured it was not going to get up to temp with the fan at 100% and the temp still falling.

I would really like to get it under control.

Thanks,
John

What is your max fan setting? I've had this happen to me, the fan is putting in too much air and venting the heat right out the top.

Maybe limit it to 20-30% max. It looks like after that the fan starts cooling off the cooker.

You might also want to try running without water next time. The HM might work a bit better and more responsive without a big heat sink that can't get over 212.

The first thing I would suggest is you move away from the Kingsford Original briquettes and use lump coal instead. Briquettes are compressed coals with some additives in them that I really don't want on my food, I tend to burn them until they are white before I put my food on them. This is pretty much impossible to accomplish with a long cook in a smoker. Lump coal is real wood, it's not manufactured like a briquette, and it burns a little hotter. I think things will go a little easier for you if you use lump coal instead of briquettes... At least that is my personal preference.....

I know this was your first test cook, so the early start is understandable, but burning for that long without food on is just producing more ash in your burn pan. As you have found out, the ash can restrict the air flow, so the less ash in the pan the better.

As Bryan pointed out, when your fan is running so high it generally means you are running low on coals or you are choking off the fire for lack of air. It is also possible to push too much air through the smoker as William pointed out. If the fan is moving too much air it can push the heat right out the vent. It's hard to tell if this is your issue or not without being there. If your fire doesnt seem almost dead when the fan is ramping up to 100% then perhaps you should set your max fan speed at something less than 100%.

This brings to mind the other option, the servo damper. I love the blower system for stoking the fire to temp and for fast recovery from lid open, but for long cooks like this I much prefer the servo damper. Reason being, there is much less air flow through the smoker when you let natural convection do the stoking. With less air flow you burn less coals, and make less ash, and are not forcing your heat out of your top vent. This means you don't need to add as many coals for long cooks and don't need to clean out as much ash. So the servo damper control system IMHO is a much better option for long cooks like this. With recent developments in V9 HM software release you can have the best of both worlds, using the fan set to run only at 100% and the servo damper will control the pit when it moves below 100%. This is really nice cause it will stoke your fire up fast, but once the fan turns off it will stop pushing your heat out of the top vent.

Finally, practice makes perfect! Since I don't have a WSM myself I can't give you any real pointers on cooking with it, but keep cooking with it and eventually you will get all this worked out and your cooks will start to go much easier for you...

I limit my max fan speed to 30% or else I end up pushing all the hot air out of the smoker. Yes the fire will eventually stoke up to use all that air, but then you will have some major over shoot.

dave

John :

Do you have any model or brand information on the fan?

Alan Erickson said:

John :

Do you have any model or brand information on the fan?

Click to expand...

Alan, it seems from his other post here that he is using the fan specified in the HM BOM, which has 6.7CFM flow if I recall....

RalphTrimble said:

Alan, it seems from his other post here that he is using the fan specified in the HM BOM, which has 6.7CFM flow if I recall....

Click to expand...

Yes, its the fan recommended in the BOM for the HM4 build

D Peart said:

I limit my max fan speed to 30% or else I end up pushing all the hot air out of the smoker. Yes the fire will eventually stoke up to use all that air, but then you will have some major over shoot.

dave

Click to expand...

D Peart,
What smoker are you running?
I'll try limiting the max fan speed.

I run a UDS

dave

2nd Smoke with HM4

Figured I would have comments from the Graph thread posted here so that thread does not get filled up with comments.

Here are the results and comments of Ribs on the Weber Smokey Mountain 22.5" with HM4, 2nd smoke using the HM4

Please post any comments in this thread

Smoker was started up around 11:30 AM. Full of coals, 40 briquettes were lite in a chimney and scattered around. Using Kingsford Original.

2 bottom vents closed, top open about 0.25, Fan mounted in bowl and toggle bolted in place, open 100%. Water pan foiled without water.

WSM 22.5 has nomex gaskets and probe grommet hole.

Smoker came up to temperature (225) and held it nicely about an hour later.

2 St. Louis ribs from Costco of about 3 lbs each.

Settings were:
B: 4
P: 3
I: .005
D: 5

Fan:
Started at 100% max
12:50 PM fan set at 60% max
4:30 to 5:30 fan set at 70% max

Smoke wood:
6 oz Apple
6 oz Hickory

How it went:
Time Temp Comments
11:30 AM 80 Started smoker, fan set at 60% max
11:42 AM 193 Brain fart, top vent closed, opened to 100%
12:00 PM 199 set fan to 100% max
12:30 PM 223 Put meet on, added wood, 6oz hickory, 6oz apple
12:50 PM 221 set fan to 60% max
01:00 PM 223 smoker up to temp
03:00 PM 211 Foiled ribs, 2tbs apple juice each, set smoker to 250 (wanted to speed up the cook, figured smoke was done since being wrapped in foil)
03:20 PM 250 smoker up to temp
04:30 AM 247 Removed foil
05:25 PM 218 Stoked coals
06:00 PM 225 baste with SBR sauce
06:15 AM 248 DONE!



Questions/observations:
This cook went better then the last one.
One reason I think it went better is because I removed the 2nd coal grate stacked on the first.
No water in the pan, just foiled. Have to see if I continue without water. Maybe try the clay pot method?
Had to stoke the coals more then I thought I would have to.
I think I'll redo the blower and have it blow under the coal grate so it provides air from under the coal, instead of just on 1 side? (WSM has 3 air inlets spaced around for a reason)

Looks alot better. I know this one was for a shorter time, but do you feel the fuel consumption was any better?

Last time you mentioned having to refuel several times.

Also, What are you looking to happen with the clay saucer? I like the empty pan method because it deflects the direct heat, but doesn't add a lot of heating lag to the system like water or a clay brick. Those are desirable qualities when not using the HM, but a hinderance when you are.

Be careful directing airflow under the coals, the fan tends to kick up the ash.

In my smoker with the "air burner" I leave the HM fan max speed at 100% and I have yet to have any problem with ash. The coals (and therefore ash) sit right on top of the "air burner" but I think because there are many small holes in it (and the stock HM fan doesn't blow that hard) there isn't enough air movement in any one spot to kick up ash to far...

Did not have to refuel, just had to stoke the coals a few times.
It seems that it burns ok by the blower vent but does not get the coals going further away as it burns. I believe the air is entering and then going up and not getting to the fire.
CO2 is heavier and I think it's sitting there smothering the coals and the O2 is just going up. (That is just my wild *** guess)

I've thought about the ash blowing up. But with the increased efficiency of the air burner, I should be able to set my max fan speed lower and not have ash kick up.
I have an idea about how to do it without cutting a hole in the smoker, if it works out I'll post the details.

Thoughts?

John, I wish I could help but I don't know how the ash pan of the WSM is constructed. My cheapo smoker had one small hole in the center of the burn pan and that was super convenient for setting up the "air burner". If you would post some pic's of the WSM burn plate and bottom section with vents I might be able to make some suggestions. If I happen to be out and about and see a WSM on display in a store I will try to get a look at the burn plate and make suggestions...

I used 3/4" copper to connect my fan and make my "air burner". but I don't think it needs to be that big. You might try some smaller flexible copper, might be able to snake that in there somehow?

John, another approach that might work for you would be to crack open the vent a bit on the opposite side of where the HM is connected. This would allow a little convection air flow in on the side you have a hard time stoking. As long as the pit temp still drops when the HM fan goes off the HM should still be able to control the pit....

I used a slightly larger fan for my HM and if given a chance it will blow ash, if it gets over 70%.

My quick and dirty method of diverting air around is to just use some foil (also my cheap solution to seal my smoker). Fold enough of it to make it heavy and shape it to fit against the vent inside. Instant diverter.