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Thread: Heatermeter on Pellet Grill

  1. #1
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    Heatermeter on Pellet Grill

    I recently purchased a Pit Boss 820 because it was on sale at Lowes for $400. I've done my research and found that it has issues with large temperature swings which brought me to the Heatermeter. I know this topic has been explored before, but I've only seen discussion. It doesn't appear that anyone has actually posted a successful method for setting up a pellet grill using the Heatermeter.

    For those of you not familiar with how pellet grills work, I will give a short explanation. There are 4 major components: the auger, fan, igniter, and fire box. On startup, the igniter is lit and the auger feeds pellets to the fire box. The fan will start up and this will give you an initial burn. If startup is successful the fire box will have a flame and pellets are fed into the firebox where they are burned throughout the cook. In the case of the Pit Boss, the pellets are fed to the fire box through a user determined duty cycle. The length of the duty cycle is determined by the "P-setting". The auger will always run for 18 seconds each duty cycle. The length of "off" time will be set by the "P-setting". Higher "P-settings" mean longer duty cycles generating more smoke. As you can imagine, this creates the large temperature swings.

    I am going to connect the auger to the Heatermeter in place of the fan. An SSR will need to be added to take the 12V input voltage from the HeaterMeter and control the 120V fan. The fan settings for the Heatermeter will be adjusted to pulse mode. This will mean the fan (auger) will be ON/OFF. My duty cycle will be a set 20 seconds and the auger ON time will now be variable instead of a set 18s using the OEM controller.

    I believe this will work out well, but the part I'm struggling with is the start up. I was thinking about having the fan, igniter, and auger attached to toggle switches to swap them to manual mode and do the startup manually. However, is there a way to automate the startup? I was thinking maybe an alarm that would run the auger, fan, and igniter if the temperature was below X degrees. This would also help recover from a flame out during a cook.

    Any thoughts?

  2. #2
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    Going to do my first cook this weekend with no controls to try to understand the pit a little better. I believe everything that I am looking to do can be controlled through programming. However, I have limited knowledge on the programming. I was still thinking of using the same concept as above where the startup is performed manually. I'll switch it to auto mode where the auger will be controlled by the HM "fan" pulse function. The fan will be 100% and the igniter will be set to off.

    I'm also considering tinkering with the fan. I think having two PID loops controlling the auger and fan will get complicated. Instead I was looking at having the fun run a fixed ON/OFF duty cycle. The thought here is that the fan will run for x number of seconds to keep the fire going and will shut off for y number of seconds to let the fire die down and hopefully produce more smoke than a 100% ON fan.

    I think this can be done using the programming, but not sure if I'm going to be able to figure that out. So I was looking to connect the fan to an adjustable cycle timer circuit that I found cheap on Amazon https://www.amazon.com/exec/obidos/A...V863MR/tvwb-20

  3. #3
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    So I'm looking to finally start this project. Here is my electrical schematic:


    What I came up with is a manual override on
    1. Fan
    2. Auger
    3. Igniter

    I use the override on start up to
    1. Feed the pot pellets
    2. Turn the igniter on
    3. Turn fan on once pellets have fire

    I use the override on shut down to:
    1. Run the fan to burn out what's left in the pot.


    Once start up is complete, I turn all overrides off and control is given to the HeaterMeter. I will have a 20 second duty cycle where the Auger & Fan will be 100% on OR Auger off & Fan at a %setting.

    I'm trying to get a "burn phase" where I build temp, but then a "smolder phase" where I stop feeding fuel and I drop the fan speed. I hope this will create more smoke.

    I just ordered the Heatermeter parts. I'm going to wait to order the rest of the circuit in case there is any input that might change it. Looking forward to hearing what you guys think!

  4. #4
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    Pretty sure I achieve the same result with a much simpler circuit:



    The "Fan Override" will be kept closed. When the solid state relay contacts close, they will override the variable fan speed setting and operate the fan at 100%....at least I hope
    Last edited by KyleH; 09-07-2018 at 02:06 PM.

  5. #5
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    Hey Kyle,
    Awesome post. I'm curious if this wound up working for you or not. I'm looking to try something similar.

  6. #6
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    Same here, I just got a Pit Boss 7 and was wondering if anyone had successfully replaced the controller.

  7. #7
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    I too jumped in on the Pit Boss pellet grill at Lowes. Much as I couldn't use the Heatermeter to control the grill, I could monitor the first few cooks and see just how bad the shipped controller was. And it really is ugly from a stable/set temp perspective.

    I did think about adapting the HM for the pellet grill but ultimately decided against it as the Savannah Stoker (https://www.savannahstoker.com/) is a drop in replacement PID controller (and it does an excellent job). Now, it doesn't have wifi but if I need that monitoring aspect, I'll rig up a HM and let it run alongside.

    I'd download the user manual for the above if you're looking for input as to igniting, detecting flameout etc. From my running so far, the fan is always on (can't really tell if there is a variation in the speed) and I think the fan remains on so that there isn't any back burning up the auger path.

    HTH,

    John

  8. #8
    TVWBB Super Fan
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    Thanks for the info and link. I really woud rather use the heatermeter but I agree it would be much easier to just replace it with a pellet controller. I'm now
    thinking of trying to retrofit the rec-tec, its only 99 and has wifi.

  9. #9
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    Hey guys, I started traveling heavily for work shortly after making the post. I never got around to do it.

    I may do this in the next couple of weeks. Heatermeter has been sitting in my garage for almost a year now! If anyone is interested, here are the components (still in my amazon save for later) I planned on using.

    SSR: https://www.amazon.com/exec/obidos/A...7ZTN08/tvwb-20 $9.99
    SPST Switch: https://www.amazon.com/exec/obidos/A...WWZ0GK/tvwb-20 $7.98 (includes 3)
    Fan Speed Control: https://www.amazon.com/exec/obidos/A...F9DAL2/tvwb-20 $16.67

    If I get around to this, I'll probably create a model for the enclosure that can be used for 3D printing. I will also do my best to document so others can follow.

    EDIT: To anyone else looking to do this. The circuit I previously posted will not work the way I wanted it to.


    I'm a mechanical guy so I thought, oh I just need a check valve for the branch of the solid state that powers the fan. I don't think adding a diode will work the way that I want it to in an AC circuit.

    I will post the final build if I am successful. I think I will need two solid state relays, one for the auger and one for the fan. That will isolate the auger so that it will only be powered when I flip the normally open switch during start up or when the heater meter decides to turn it on.
    Last edited by KyleH; 06-22-2019 at 06:13 PM.

  10. #10
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    One thing I would say is that you need to make sure that the SSR you use is genuine. It's worth paying a little more for one vs getting a dodgy one that fails closed.......

    John

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