Control board the problem or user problem?

[ga/smoker]

I own a Pitboss classic. After a year and a half started to get run away, temps. Not all the time but also had a huge temp swing of up to 50 degrees as well. So I purchased a PID Control modified my hopper to fit the new board, upgrade the burn pot and new glow rod, and new temp sensor. After installing the new control still ran away, called the company (leaving the name out of it for now) they suggested I install a chimney and a heat diffuser. Easy enough, made no impact. So mailed the controler back for an update, no impact. Board number 3 no impact. So I am set to return the controller and I ordered a factory replacement, no impact. Still running away . So I am kind of at a loss of what could be causing this. I have other smokers I can use so thinking I should forget pellet grills, but when it worked I really enjoyed the ease of it vs my barrel or smokehouse. Any ideas tips trick ect please?

 

[JC in GB]

Too much heat can only be caused by too much air and fuel. Have you checked the airflow through your pit?

That would be my first place to look if I was confident that the controller was measuring properly.

Is your control probe gunked up with grease and debris? That will confuse the controller. Is the thermocouple in the proper place to regulate?

JC

 

[ga/smoker]

I put the new probe in the same place as the original. I can try and take the chimney back off. Ill try that tonight when i get home

 

[bill1]

So you've changed the controller multiple times but the probe (for the controller) only once? How does that probe read (on the controller itself)? Does it read "true" against another trusted probe in the same approx location? If it reads low (partic if it's an intermittent problem) your controller will be pouring on the fuel and air thinking you need more heat, when you don't.

 

[bregent]

I'd say it's neither the control board or the user. If you've changed the board several times, and even used a PID controller, something else is probably wrong and not allowing the controller to maintain set temp. Could likely be an airflow problem. Has the fan been checked?

 

[kilo charlie]

Wait... Explain where you're seeing these temp swings at? Are you going by the digital display or a remote probe or an oven thermometer that's on the grate?

 

[ga/smoker]

I haven't replaced the fan. It is coming off and on. Using the PID board it the fan will even slow. I have used a wireless temp prop on the grates a few inch from the side where the control prop is. I see a few degrees difference no big deal but the control even says its higher. For example i set it for 200 it will reach 200 and then continue to climb till I open the lid around 300. Does seem to stablize around 360. The grill has the holes in the back i put back on the block off plate and removed the chimney bad weather came in so I didn't test it. Thank you for the replies I know I have to be missing something

 

[kilo charlie]

For around $4 you can buy an oven thermometer at Walmart.. put it on the grate where you are going to place your food. Do not put it over the burn pot for obvious reasons... Do you have a slide that covers the burn pot and of so could that be out of place?

 

[ga/smoker]

For around $4 you can buy an oven thermometer at Walmart.. put it on the grate where you are going to place your food. Do not put it over the burn pot for obvious reasons... Do you have a slide that covers the burn pot and of so could that be out of place?

I have a remote thermoworks use it for my other smokers to. I have the plate in place even ordered a new heat diffuser

 

[bill1]

Are we talking about 100F runaway temperatures in the middle of a multi-hour cook, or just on startup? I'd say that's normal on startup.

 

[ga/smoker]

Are we talking about 100F runaway temperatures in the middle of a multi-hour cook, or just on startup? I'd say that's normal on startup.

On start up but it never comes down. If its set for 200 it will go to well over 300. Never stablizes

 

[bill1]

On start up but it never comes down. If its set for 200 it will go to well over 300. Never stablizes

I've seen similar behavior. I think it is truly trying to regulate back down to the lower temp, but it's very slow going.

They program these units so no matter how over-temp from the setpoint they are, they'll always feed pellets at some min frequency (max timing) interval. So as long as you're "feeding the fire", it can take a long time to come down and get into reasonable regulation. Manufacturers do this because letting the fire go out not only leads to angry customers but can lead to a big safety issue. Hence ensuring the fire keeps going is a huge concern for the control programmer.

Quite simply, the problem is that the control system really can't tell when the fire goes out. (A narrow-band IR sensor would solve this, but that's added cost and complexity.) If they truly, completely, stopped feeding pellets when the unit was above the setpoint, which would bring the temp down quicker, the fire could go out, and then yes, it would eventually under-temp, but with the fire out, all the control system knows to do is to feed more pellets until the crucible overflows. The typical modern customer at some point says, "Hmmm, it's 'hung up', like a blue-screen, I better re-boot." At that point, pulling the plug, then restarting, will turn on the igniter element, and you can have a huge fire with all that fuel overflowed from before.

You've got a separate Smoke Mode on your Pit Boss, right? What I do when it seems to be taking forever to come down in temp after start-up, is I go into Smoke Mode and dial it in for the max length of "off auger" timing, which for me is SP=9 or a feed every 120s. That's the sure-fire way to get the temp to come down, although it will still take 10-30 minutes. But these are more smokers than grills, so on smoker time scales, that's not really very long. (Smile) As I start approaching my setpoint I set the Smoke Mode setting to SP=2 or 3 which ensures I don't too quickly drop below 160F, which I think is a good outdoor cooking min for food safety reasons. At that point, switching back to Cook Mode at my original desired setpoint of 200F, usually gets it into good regulation within 15 mins or so. Of course this is a stick burner (just little sticks) so good regulation can mean a total swing of 40 degrees. (But most true pitmasters can't do that good!)

I note that a lot of instruction manuals seem to instruct people to set up in Cook Mode first, but then go into Smoke Mode right away, which I think is their way of saying what I just said without the "why" explanation.

Hope this helps.

 

[ga/smoker]

I've seen similar behavior. I think it is truly trying to regulate back down to the lower temp, but it's very slow going.

You've got a separate Smoke Mode on your Pit Boss, right? What I do when it seems to be taking forever to come down in temp after start-up, is I go into Smoke Mode and dial it in for the max length of "off auger" timing, which for me is SP=9 or a feed every 120s. That's the sure-fire way to get the temp to come down, although it will still take 10-30 minutes. But these are more smokers than grills, so on smoker time scales, that's not really very long. (Smile) As I start approaching my setpoint I set the Smoke Mode setting to SP=2 or 3 which ensures I don't too quickly drop below 160F, which I think is a good outdoor cooking min for food safety reasons. At that point, switching back to Cook Mode at my original desired setpoint of 200F, usually gets it into good regulation within 15 mins or so. Of course this is a stick burner (just little sticks) so good regulation can mean a total swing of 40 degrees. (But most true pitmasters can't do that good!)
Hope this helps.

I have the aftermarket PID board in now I will set it to lo smoke and see if it ever stabilizes this weekend with the chimney off. But that is some good info maybe it needs to come back down I just figured it never went 100 plus over before something must be wrong. If this doesn't work I will replace the fan and the temp prob one more time. And if that doesn't work. I will scrap it lol. I could have bought another pellet grill at this point

 

[MJB05615]

I had a PB700 for a while.The 1st year it worked very well about 90% of the time with minor issues 10%.
When year #2 started, it never worked right again. Took it apart, cleaned, checked and changed what I could, etc. Finally put it in the shed, and went back to my MES40, made some mods from this forum, and haven't looked back. When these PB's work properly, they're excellent. But when you are all set to start smoking some meat, and you don't know for sure whether it will work this time or not, it takes all the fun out of it.
Good luck, let us know your results.

 

[Cody_Mack]

I've seen similar behavior. I think it is truly trying to regulate back down to the lower temp, but it's very slow going.

They program these units so no matter how over-temp from the setpoint they are, they'll always feed pellets at some min frequency (max timing) interval. So as long as you're "feeding the fire", it can take a long time to come down and get into reasonable regulation. Manufacturers do this because letting the fire go out not only leads to angry customers but can lead to a big safety issue. Hence ensuring the fire keeps going is a huge concern for the control programmer.

Quite simply, the problem is that the control system really can't tell when the fire goes out. (A narrow-band IR sensor would solve this, but that's added cost and complexity.) If they truly, completely, stopped feeding pellets when the unit was above the setpoint, which would bring the temp down quicker, the fire could go out, and then yes, it would eventually under-temp, but with the fire out, all the control system knows to do is to feed more pellets until the crucible overflows. The typical modern customer at some point says, "Hmmm, it's 'hung up', like a blue-screen, I better re-boot." At that point, pulling the plug, then restarting, will turn on the igniter element, and you can have a huge fire with all that fuel overflowed from before.

You've got a separate Smoke Mode on your Pit Boss, right? What I do when it seems to be taking forever to come down in temp after start-up, is I go into Smoke Mode and dial it in for the max length of "off auger" timing, which for me is SP=9 or a feed every 120s. That's the sure-fire way to get the temp to come down, although it will still take 10-30 minutes. But these are more smokers than grills, so on smoker time scales, that's not really very long. (Smile) As I start approaching my setpoint I set the Smoke Mode setting to SP=2 or 3 which ensures I don't too quickly drop below 160F, which I think is a good outdoor cooking min for food safety reasons. At that point, switching back to Cook Mode at my original desired setpoint of 200F, usually gets it into good regulation within 15 mins or so. Of course this is a stick burner (just little sticks) so good regulation can mean a total swing of 40 degrees. (But most true pitmasters can't do that good!)

I note that a lot of instruction manuals seem to instruct people to set up in Cook Mode first, but then go into Smoke Mode right away, which I think is their way of saying what I just said without the "why" explanation.

Hope this helps.

Impressive analogy, bill1 . I bet you have "tuning" in your vocabulary. The PID controller is not allowed to do what it is designed to do, due to parameters that it cannot see, or is not equipped with. Yes, it needs flame detection.

 

[JWFokker]

What model cooker and what aftermarket controller did you get for it?

It's definitely feeding in pellets faster than they're burning.

I have an older model Pit Boss with the old "dumb" timer based controller. I play with the p-setting (pellet feed rate "delay") to get it in the temp range I want. The temp setting on the controller controls the fan speed more than anything.