Pellets and humidity?

[hillbilly jim]

I bought my first AMNPS and a sack of Hickory pellets just recently. I set everything up yesterday afternoon to do an overnight cheese smoke. This morning, I discovered the pellets went out about half way through the burn.

I'm about a half mile ASL here on the Blue Ridge, so the humidity spikes at night during the summer. Would the humidity spike cause the burn to fail?

Thanks, fellas!

Jim

 

[daveomak]

What are you using as a cook chamber...  does it have good air flow...  

I have recently made this mod to my AMNPS and I don't have to dry them like I did before this mod....    I think it improves air flow to the maze from below.......

AMNPS LEGS 3 001.JPG

• daveomak
• Jun 17, 2016

 

[hillbilly jim]

I have a Masterbuilt 44 inch propane smoker. The hole in the bottom of the cabinet above the burner assembly is 8"X14". The exhaust vent is four slots, 1/2"X2,1/2",which translates to the area of a 2, 1/2 inch circle.

It doesn't appear as if I'm having draft issues. I've got a thread started in another section about that.

 

[daveomak]

Does smoke come out the door cracks when cold smoking like you were for the cheese....

 

[hillbilly jim]

I have a Masterbuilt 44 inch propane smoker. The hole in the bottom of the cabinet above the burner assembly is 8"X14". The exhaust vent is four slots, 1/2"X2,1/2",which translates to the area of a 2, 1/2 inch circle.

It doesn't appear as if I'm having draft issues. I've got a thread started in another section about that.

 
I have a Masterbuilt 44 inch propane smoker. The hole in the bottom of the cabinet above the burner assembly is 8"X14". The exhaust vent is four slots, 1/2"X2,1/2",which translates to the area of a 2, 1/2 inch circle.

It doesn't appear as if I'm having draft issues. I've got a thread started in another section about that.

 
Does smoke come out the door cracks when cold smoking like you were for the cheese....

Yes Sir, it does. Does that indicate the exhaust is too small?

 

[daveomak]

 
I have a Masterbuilt 44 inch propane smoker. The hole in the bottom of the cabinet above the burner assembly is 8"X14". The exhaust vent is four slots, 1/2"X2,1/2",which translates to the area of a 2, 1/2 inch circle.

It doesn't appear as if I'm having draft issues. I've got a thread started in another section about that.

 
I have a Masterbuilt 44 inch propane smoker. The hole in the bottom of the cabinet above the burner assembly is 8"X14". The exhaust vent is four slots, 1/2"X2,1/2",which translates to the area of a 2, 1/2 inch circle.

It doesn't appear as if I'm having draft issues. I've got a thread started in another section about that.

 
Does smoke come out the door cracks when cold smoking like you were for the cheese....

Yes Sir, it does. Does that indicate the exhaust is too small?

  YES !!   Poor air flow....   When the smoker fills with smoke, that is used air AND there is not enough oxygen left to burn the pellets....

 

[daveomak]

There is also too much air entering the smoker...   Cut out a plate to cover the bottom air inlet and drill 4 each 1" holes in it and see if that solves your problem.....  You may still have to drill some 1" holes in the top of the side walls to exhaust more air......

Pictures of the exhaust and hole in the bottom would help.....

 

[hillbilly jim]

Yesterday, I filled my AMNPS and then put the pellets on a tray in the oven at 300* for an hour. I put two butter stick size pieces of sharp cheddar and about a half cup of course sea salt in the smoker about 5:30 PM. I got the pellets lit, checked on it an hour later and they were still producing smoke. It's now 7 AM, the pellets are still smoking and there's half of the last run in the smoker still left. I'll have to take it out here in the next hour or so.

That's not exactly a laboratory level scientific test, but I do believe drying the pellets in the oven had something to do with a successful all night run.

As for the draft issue, I'm going to solve that problem today. I didn't sleep through 30 years of industrial HVAC.

 

[hillbilly jim]

This is after 14 hours. I pulled the cheese, but left the salt to finish the burn.

IMG_4948.JPG

• hillbilly jim
• Jul 18, 2016

IMG_4947.JPG

• hillbilly jim
• Jul 18, 2016

 

[hillbilly jim]

Back to the issue of humidity.....

I set up to do another cold smoke yesterday afternoon. Got everything right, lit the AMNPS, shut the door and left it to run all night.

Looked at it about 6 AM this mornin' and it was still lit, but only barely. And only half of the pellets had burned. Didn't get anywhere near what I wanted in color.

During the night, the humidity spiked to 100%. The pellets were cotton dry when I lit 'em and I've got plenty of draft, no problem with that. I am now firmly convinced that high humidity will retard the burn.

 

[sigmo]

That has been my observation, too. I'm at about 5200 feet here. We see very low humidity in the day, when temperatures are high, and, of course, higher relative humidities at night with the cooler temperatures.

At high smoker temperatures the pellets remain dry. But for cold smoking, or even jerky-making, the humidity outside the smoker can draw in, and re-humidify the pellets, leading to them going out. I had it rain while I was making some jerky a week or so ago, and the pellets went out on me. The relatively low temperature of the smoker and the extreme humidity, along with poor draft (due to the low smoker temperature) are what I believe contributed to that failure.

When I've cold smoked cheese in the winter here, when things are really dry, I haven't had the problem. So I really do think pellet humidity is one of the major factors for me at this elevation.

 

[sigmo]

Well, I just had another humidity-related pellet failure.

This happened as I was smoking some nuts right after a rainstorm. This resulted in very high humidity levels for these parts.

The pellets were dried in my convection oven for a few hours at 325 degrees immediately before the smoke, and they lit very easily and burned well for about an hour. Then they slowed down and finally died out.

I believe that at this elevation (5300 feet), when the humidity is very high, even with pre-dried pellets, they absorb moisture from the incoming air as the burn proceeds, and then they slow down and finally die out.

They burned one row completely, made the turn OK, but then died out about an inch into the middle row.

I may be able to modify the air path to get the incoming air better directed right at the location where I set the pellets. But it may just be a humidity/altitude problem.

It's very rare for me to have this sort of humidity, so it might not be worth doing much to fix it for me. But it does show me that even in a system that normally has no problems, higher than normal humidity can kill the burn.





Tabbed in.

 

[daveomak]

At 5300', you have exceeded the limit for oxygen in the air...   Try legs on the AMNPS and maybe a small fan.....  or use the AMNTS...  give Todd a call...  He'll take care of you...

Let Us Help

• A-MAZE-N Products, Inc. 
• 1932 Shawnee Road, Eagan MN  55122-1032
• Ph: 651.352.2831
• Fax: 651.352.2871

 

[sigmo]

 
At 5300', you have exceeded the limit for oxygen in the air...   Try legs on the AMNPS and maybe a small fan.....  or use the AMNTS...  give Todd a call...  He'll take care of you...

Let Us Help

• A-MAZE-N Products, Inc. 
• 1932 Shawnee Road, Eagan MN  55122-1032
• Ph: 651.352.2831
• Fax: 651.352.2871

Thanks!  I really do appreciate the suggestions and offers of help.

I'm not unhappy with the AMNPS.  It's really the best thing ever for my MES-40.  And 99% of the time, it's been working just dandy for me.

I set the unit on the metal bars that run across the smoker like this:

p2100543103.jpg

• sigmo
• Aug 12, 2016

So that keeps it elevated two or three inches above the drip pan on the bottom.

I also run with the chip hopper completely removed and the sliding drawer open partway as shown.  And, of course, the damper at the top of the smoker is always fully open.  Also, I never use the water tray thing.

p1915251024.jpg

• sigmo
• Aug 12, 2016

And almost always, I get complete burning of whatever amount of chips I use.  So it has worked very well for me. 

BUT.  It's usually very dry around here.  But lately, we've had more humidity here than normal.  And it's actually rained a few times right when I was doing some smoking, or just beforehand.  And that pushes the humidity way up, of course.

So with regard to how humidity affects the burning of the pellets, what I've observed has been that even starting with dried pellets, an hour or two into the burn, when it's very humid here, the pellets will go out.  So it seems that the pellets absorb moisture from the incoming ambient air over time, and when their moisture level reaches a a certain threshold, the combination of moisture and lower air density at this elevation is just too much to allow them to continue to burn.

As an experiment last night, even though the nuts I was smoking were already done, and had gotten a really very pleasant amount of smoke (the pecan halves are fantastic!) I stuck my "magnetic fan" directly over the inlet hole and fired it up.

p1940794602.jpg

• sigmo
• Aug 12, 2016

p1887537727.jpg

• sigmo
• Aug 12, 2016

With it positioned directly over the inlet, it forces a lot of air through the smoker, so I adjusted the top vent damper to half open.  There was still a nice breeze blowing up out of the smoker that you can feel easily with your hand.  I wanted plenty of airflow, but not so much that it would prevent the heating element from being able to keep the smoker up to temperature.  I watched it for a while and was satisfied that the heater was cycling off every now and then, telling me that the smoker's control, at least, thought that the temperature at its probe was where it wanted to be.

Interestingly, with the forced air flow, there is actually very little hysteresis in the temperature control.  It'll cycle off when the temperature is at the setpoint, and cycle back on only a couple of degrees below the setpoint.  So that gave me a glimpse into the operation of the controller that I normally don't get.  Without the fan forced air flow, the unit cycles farther up and down due to the heat capacity of the heating element creating a lot of overshoot.  But I digress!  :)

With the fan forced operation running, with the vent at half open, I was getting a good plume of smoke out the top, and I figured, if anything, the pellets might burn way too fast and burn themselves out far faster than we'd really like.  So I went back to work for a couple of hours, and when I came back, expected to find all of the pellets burned.  But in fact, what happened was the row that was burning (which was about 7/8ths of the way down the first row) burned down around the corner and started back up the middle row, and got about 1/8th of the way into the middle row, and then went out.

So even with the forced air, it went out.  But again, it was quite humid and cool out.  Probably about 65°, and really muggy feeling (of course, muggy to someone in Wyoming is a relative thing since humidities are often in the single digits here)!

I think I had too much air flow, actually.  For real smoking, it would've been far too much air through the smoker.  But theoretically, I could throttle the top vent and achieve any air flow I want.  And I may play with that.  But for the purposes of getting the pellets to burn, massively excess airflow didn't help in this case.  The humidity and air density here were just too much for it, I think.

One of the things that plays a HUGE part in wildland fire behavior is humidity.  You wouldn't think it'd be a big deal, but it really is.  When fighting a fire, people pray for the humidity to go up even just a little bit.  And at night, the relative humidity usually does go up.  And that's why fires are often said to "lay down" at night.  The burning slows tremendously.  In fact, this recent pulse of humidity that has caused me to have these two pellet burning failures also has allowed firefighters to finally gain the upper hand on several of the large forest fires burning around the state.  So that's fantastic!

And I've had these failures at night, too, when the relative humidity has been highest.

So I think it's interesting to realize that humidity really has a large effect on how things will burn.  In firefighting, they refer to different kinds of dead plant fuels based on their diameters.  And of course, the smaller the diameter of the dead wood or grass, the faster it absorbs and releases moisture.  And the small stuff is also the best "kindling".  So humidity affects its moisture content rapidly, and that has a very quick effect.

The wood pellets are made of compressed sawdust sort of stuff.  And that helps them burn, of course.  But it also makes them very susceptible to absorbing or releasing moisture based on the ambient humidity.  So I think that even though I started off with oven-dried pellets, the high humidity has been moistening them fairly quickly of late.  And when they're moist, they just don't want to burn at this elevation because, as you've said, oxygen levels are right at the limit.

I'm curious as to why the tube-shaped smoke generator would work better.  It seems like it'd be about the same.  But maybe using sawdust rather than the pellets would help.  But then, I've got a nice stockpile of pellets. Maybe I should grind some of them up into the dust and give that a try.   I'll need another good high-humidity night, and maybe test the dust side by side with the pellets to see if it works better.

Another thing might be to set things up so that the pellet burner sits above or at least more directly in the air-stream coming off of the heating element so that that heat drives the moisture out of the pellets constantly.  Maybe I've created a dead-zone in my smoker with the foil I have above the AMNPS as a drip shield.  I've seen posts where people add some stovepipe inside of the smoker to direct the incoming air towards the smoke generator.  I may have to play with that because it'd be easy to do and simple.

But really, for me, the main reason for even posting about this was because I'd seen this thread about humidity affecting things.  And based on my experience of late, and then thinking about it with respect to wildland fire behavior, it all makes sense.  So thought I'd chime in with my experiences.

Since the system I have now has worked so well for a number of years, I haven't been motivated to alter it.  But if it's going to continue to be wet whenever I get in the mood for some smoking, then I'm gonna have to tinker some more!  But then, I love tinkering.  :)

I think the AMNPS is a dandy product.  As I've said, it's made all the difference in the world to how my MES works.  The MES was more or less useless as it came because the chips wouldn't burn unless the heating element was cycled on, and that, of course, is (and should be) determined by the heat demand of the system.  The smoke generation needs to be independent of the heating system.

So don't take these posts as customer complaints.  I'm just interested in all of this and found the humidity angle quite appropriate for what I've run into the last few times out.

As with anything, I will take this as a challenge because I figure the right modifications may make my pellets burn despite high humidity and elevation!  There has to be a way! 

Maybe we need a segment on the forums for "high altitude smoking".

Thanks!

 

[wade]

 
So with regard to how humidity affects the burning of the pellets, what I've observed has been that even starting with dried pellets, an hour or two into the burn, when it's very humid here, the pellets will go out.  So it seems that the pellets absorb moisture from the incoming ambient air over time, and when their moisture level reaches a a certain threshold, the combination of moisture and lower air density at this elevation is just too much to allow them to continue to burn.

The smoldering pellets will also create more moisture so compounding the problem of the high humidity.

The fan works well and I use one on my cold smoker. It helps to keep the air flowing over the AMNPS but it also helps to remove moisture when cold smoking salmon. I found that it was easier to control though when I switched to using an inexpensive variable speed fan

http://www.frozencpu.com/fan-109.html

 

[sigmo]

 
So with regard to how humidity affects the burning of the pellets, what I've observed has been that even starting with dried pellets, an hour or two into the burn, when it's very humid here, the pellets will go out.  So it seems that the pellets absorb moisture from the incoming ambient air over time, and when their moisture level reaches a a certain threshold, the combination of moisture and lower air density at this elevation is just too much to allow them to continue to burn.

The smoldering pellets will also create more moisture so compounding the problem of the high humidity.



The fan works well and I use one on my cold smoker. It helps to keep the air flowing over the AMNPS but it also helps to remove moisture when cold smoking salmon. I found that it was easier to control though when I switched to using an inexpensive variable speed fan


http://www.frozencpu.com/fan-109.html

I like the variable speed fan. That would make it easy to set the air flow you want. I can see how cold smoking would benefit from forced air since you get very little convection draft.

But I've actually had great luck even with no fan, in winter here cold smoking because it is so dry then, I think. But the variable speed would give more positive, controlled flow under all conditions.

What elevation are you at?

Tabbed in.

 

[sigmo]

Oh.  And as a follow up:

The cold smoking of the salmon is probably a lot like making jerky in that you're trying to remove a lot of moisture, yet you're doing it at a relatively low temperature.  For jerky, I don't cold smoke it, but I do smoke it at a fairly low (by meat cooking standards) temperature.  And this is a place where I ran into trouble the last time out.  Due to the not-so-hot temperature in the smoker, and the high humidity, it was taking forever for the jerky to dry for me.  There was just such a large surface area of wet meat that it must have had the humidity in the smoker up to very high levels.

And that's when I quickly put the magnets on that fan and slapped it over the inlet hole.  Once I did that, the final drying phase of the jerky-making went just fantastic, and it dried to my liking in less than two hours.  (It had seemed stalled before that).

I might have to try the fan for cold smoking cheese.  I've only done cheese in the past, during winter when it's been very cold outside.  With the fan, I suspect I can get good burning of the pellets and also keep the temperature in the smoker cool even when it's not freezing outside!

I will get a variable speed fan, though.  That really does seem like a good way to go.

And I think I'll look at the airflow within the smoker between the heating element/inlet and where I set the AMNPS.  I may build a shroud of some sort to direct the incoming air at the AMNPS just to make sure it receives fresh air.  Things are still getting fairly humid at night here right now, so I can do some experimenting.

 

[wade]

What elevation are you at?
 

15m (50 feet)

 

[wade]

 
Oh.  And as a follow up:

The cold smoking of the salmon is probably a lot like making jerky in that you're trying to remove a lot of moisture, yet you're doing it at a relatively low temperature. 

To cure traditional smoked salmon, once it has been cured for 24 hours using a dry brine of 1:1 salt:sugar it is then smoked for 24 hours at about 20-25 C (68-77 F) for up to 24 hours. The dry brine starts the cure by increasing the salt and removing some of the water, the smoke continues the cure by removing the remainder of the water and by adding smoke - though the smoke is predominantly a flavour agent. The moisture loss during the whole curing process needs to be ~18% of the initial fish weight. In order to do this a good air flow is required through the smoker.

 

[sigmo]

 
15m (50 feet)

Thanks!  That's helpful info for me.

 
To cure traditional smoked salmon, once it has been cured for 24 hours using a dry brine of 1:1 salt:sugar it is then smoked for 24 hours at about 20-25 C (68-77 F) for up to 24 hours. The dry brine starts the cure by increasing the salt and removing some of the water, the smoke continues the cure by removing the remainder of the water and by adding smoke - though the smoke is predominantly a flavour agent. The moisture loss during the whole curing process needs to be ~18% of the initial fish weight. In order to do this a good air flow is required through the smoker.

That sounds like it would be fantastic.

You really are getting rid of a lot of moisture in that process.  So it makes sense that you need good air flow.

I really did find that using the fan during the final drying phase of my jerky-making got the job done in a hurry.  It really made my smoker into more of a dehydrator for that phase.

Do you use any nitrite/nitrate in the initial dry brining phase with the fish?