HeaterMeter Pit Probe




Introduction: HeaterMeter Pit Probe

First and foremost, credit for the creation of this open source project goes to the appropriate places: Bryan Mayland for creating the original LinkMeter and HeaterMeter, and the rest of the community contributors for making it possible.

I'm just a new guy learning how to do this, and it took me hours and hours reading through the forums on TVWBB to figure out how to make this (http://tvwbb.com/forumdisplay.php?85-HeaterMeter-D... so I thought I'd make a single concise end-to-end instructable on how to make this amazing project.

The HeaterMeter is a combination of a digital thermometer, iPhone/web-accessible thermometer and automatic thermostat! It enables you to maintain temperatures of your smoker for long periods of time unattended, to monitor the temperatures remotely and to configure alarms so if something goes sideways, your iPhone/email will blow up with warnings that your precious BBQ meat is going off the rails. I made this because I like doing 10+hour smokes for things like pork-butts and waking up at 1, 3 and 5 in the morning to ensure the temperature was maintained started to suck. My next door neighbor has an automatic Traeger and doesn't need to do any of this stuff. I love the temperature and flavor from the BGE better, but the upkeep stinks. The HeaterMeter entirely solves this problem--the great taste and even cooking of the BGE and the automation of the Traeger. BOOM!

These are a few images of the finished product for my version of the HeaterMeter. One of the challenges of such a flexible and open-source project is that there are lots of options. The more decisions you can make the better, but that also becomes intimidating for a first-time user, so here is a list of things which worked for me and will (hopefully!) work for you too.

Step 1: Bill of Materials

Materials: ~$250 total.

  • HeaterMeter v4.2 kit (http://heatermeter.myshopify.com/collections/front... Options on this page:
    • Thermocouple Parts: Thermocouple PCB (this enables you to use it to higher temperatures)
    • Blower: Delta 60mm 6.7cfm: this is a fine fan at a reasonable price. Include it.
    • Unless you have a Raspberry Pi Model B, include that here too. (The B+ and A require modifications and the B2 is not yet supported--literally get the Model B only!)
    • This should come out to $157. It's about $5 more than buying all the parts separately, but I imagine this all washes out after shipping, hassle, etc.
  • 0.3mm electrical solder ($5)
  • 4"x8" piece of 1/2" plywood. ($2)
  • 6" of 3/4" copper tubing ($5)
  • Silicone caulking ($3.00)
  • 2 x 1/2" #10 wood screws ($1.00)
  • 3 x #10 2.5" deck screws ($1.00)
  • Cat-5 ethernet cable with ends ($5)
  • Cat-5 ethernet jack (from a home improvement store) ($3)
  • Cat-3 raw cabling (no tips) or any type of jumper cable. You only need very little of this ($1)
  • SD Card ($3)
  • HeaterMeter case. Order from this forum from the user offering to sell here if available unless you have your own 3d printer: http://tvwbb.com/showthread.php?53332-HM-4-2-4-3D-... ($30-$50)
  • Thermocouple: http://www.amazon.com/Probe-0-500C-Temperature-Coi... ($5)
  • Meat probe: http://www.thermoworks.com/products/alarm/chefalar... ($20). You can order up to 3 of these simultaneously
  • Knockout electrical panel (from home improvement store) ($1)
  • Hobby Servo ($1-$2)


  • Soldering iron with fine tip
  • Miter saw or hand saw
  • Dremel with cutting blades (you'll burn through ~5 blades cutting the metal)
  • Metal file (fine and rough)
  • Hand drill

Things to read in preparation

Step 2: Assemble the PCB

The instructions for this are awesome, so I will only add here commentary on what made this work/not-work for me. This step takes 4-5 hours for a newbie, or 2 or so for an experienced solder-meister. You are likely not the latter if you're reading this :) and can be split up into different parts

Read through these instructions: https://github.com/CapnBry/HeaterMeter/wiki/Heater...

Here is the process I recommend for making this work with the least amount of hassle:

  1. Read all the directions through even the parts that aren't necessary--e.g., I read about the Raspberry Pi A even though I used a B (15 minutes)
  2. Watch this video if you've not done much PCB (Printed Circuit Board) soldering before:
    1. I found this video super helpful--especially 4:00-7:00 about techniques for soldering.
  3. Do one section (1-2 steps at a time). Read the 1-2 steps before, those 2 steps and then the 2 steps afterwards. If I'm starting after a break, skim all of the instructions again to re-orient.
  4. Have the laptop about 1.5 feet away at all times (close enough to check, but not too close to get solder on everything).
  5. Don't drink too much coffee--my hands wiggle when I solder after 2+ cups of coffee.
  6. For each 1-2 steps, pull out all the components and label them (the kit with the printouts is helpful, but I further separated using scrap paper). That way you're only tracking 3-5 small parts at a time.
  7. Double check the components vs. the instructions again: resistors can move around, capacitors look similar. Desoldering is a bugger for a first-timer.
  8. Do a dry run of the components for the 2 steps. Ensure they're all in and look like the picture. Spend an extra 30 seconds here--it's worth it to prevent a mistake. Clip the leads. I even sometimes practiced knowing where the soldering iron would go because some of the angles are a little bit tricky.
  9. Put them back on the paper --re-sorted
  10. Solder them 2 at-a-time. Every time, check the label on the paper, the stripes/labeling on the component, and glance at the instructions
  11. Repeat.

Take your time on this step. Making a mistake here may take hours and hours (if not days) to undo. You can see comments on this thread (http://tvwbb.com/showthread.php?58559-HeaterMeter-...) from newbies who've soldered something wrong and it takes tons of work to undo. You don't want to have to redo these steps.

Pay special attention when soldering the large parts--

  • The socket for Raspberry Pi integration needs to ensure the direction is correct
  • The LCD is the most tricky thing to get right. Read these instructions and follow them. Do a full dry (NON-SOLDER) assembly and ensure the pictures look exactly right. The most common and expensive mistakes are soldering the LCD on backwards (facing the wrong direction) or soldering it in place before it's 100% flush. The instructions are great on this point.

Step 3: Test the Electronics


These instructions are perfect. The key note here is to test using a 5v USB power directly to the Raspberry Pi *FIRST*. This prevent any problems with the Raspberry Pi-PCB mating from frying the Raspberry Pi.

Also, do not play around with the board while it's plugged in ever. This is basic, but I've gotten away with it on other projects lots. This specific project is pretty sensitive because of the 2 voltages (12V and 5V), the sensitive circuitry (LCD and servos), and because of the complexity (you've got $100 of pure electronics here don't mess it up).

Make sure you test and configure your probes. That should be pretty simple and the instructions for this are very clear. Do this before you hook up the 12V power.

Step 4: Prep the Metal Panel

This blower is designed for the Big Green Egg large, but these instructions should work for just about everything.

Label "Top" "Left" "Bottom" and "Right" in an arbitrary orientation. That will make these instructions make sense.

Start out by measuring the track on your Big Green Egg. Mine was about 3.25" high and curved.

Knock out the center of the knockout panel using a screwdriver and hammer. Be careful as this takes a little bit of force and you don't want to bang your fingers. Ensure that the copper tubing fits inside the hole.

Use your dremel to cut the knockout panel by cutting two opposite sides (Left and Right) to get rid of the screw-tabs. Cut the Left side just approximately 1" away from the knockout hole and the Right side just inside those tabs. This should leave you with a rectangle and hole centered "vertically" but significantly closer to the Left side. Now cut the "Bottom" off so that the hole is closer to the bottom than the top. Depending on your measurements the only constraint here is that hole can't overlap with the tray in front or the ceramic behind once the panel goes in.

Next, we want to hammer the panel so that it will fit into the sliding slot on the bottom of your BGE. It is slightly rounded from Left to Right. I used a scrap piece of plywood to hammer it into an approximately round shape. As you can see from the images, the bend is just slight. You'll want to hammer 3-4 different slight angles into the panel and it should fit perfectly into the bottom tray and just barely fit under the top tray so that it's flush inside the sliding tray but it won't stay still. Don't worry--that's next!

Next, we make a tab which will go behind the sliding door to hold the panel in place. Make 2 cuts on the right side about the height of your tray from the bottom (about 1/2") and the distance from the top (about 1/4")--both cuts should be about 1" wide. Now cut out the corners on the Right side of the panel at about 3/4" leaving about 1/4" of raw cut in from the corner. The center is our weight-bearing tab, and the outside parts will ensure a good seal with the tray. Using the same method of hammering, bend the tab inward another 10-degrees or so.

Now the panel should slide gracefully into the trays, and when you close the sliding door, it should stay in place nicely. Test the copper tubing to fit in the hole--if it's too snug use the file to file it down. File down the edges of the panel so it's not sharp and wont hurt anyone. See pics 2 & 3 to see how the door should hold the panel in place.

Step 5: Mount the Fan and Copper Tube

Mount the Plywood to the panel

Drill 2 5/8" holes into the panel approximately 1/2" to the Right of the knockout hole. Attach the 3" x 8" piece of plywood here length-wise centering the plywood vertically using the 1/2" screws. I pre-drilled into the plywood because we're screwing into it the "yucky" way (i.e., into the plys) increasing the chance of splitting--we don't want splitting. Now check to ensure that the panel still fits into your smoker. The wood can collide with the trays. If it does, worry not! Simply unscrew it and file down that corner of the plywood to make room for the trays.

Copper Tube Time

One end of the copper tube has to mate with the fan. To do this nicely I pounded it into a square shape.

Using my hammer and resting the tube on a scrap piece of wood, I gently tapped one end of the copper into a square. Then put the copper tube through the knockout hole. If it doesn't fit snugly, just use a metal file lightly to attach it. Ensure that the fan will mount nicely to the plywood and attach to the copper tube. Adjust the angle of the tube so that it will and ensure that the square end of the copper tube is "square" with the fan (i.e. twist the tube so that it meets the fan at the right angle). Once you have this in place, screw the fan in place using the 2.5" screws and then apply silicone to both ends of the copper tube to seal it and hold it in place.

Step 6: OPTIONAL STEP: Add Servo Valve

The HeaterMeter works just fine without the servo, butI figured what the heck--I want a real thing, so I added this.

Start by drilling a 5/16" hole into the copper tube through both sides about halfway between the fan and the panel. Be careful when doing this to ensure you don't push too hard on the copper tube--it's held in place with silicone! (first picture). File down both sides of the hole to get rid of the scragglies.

Then cut a piece of 10-gauge copper wire about 4" long. Bend it 90-degrees 1/2" from one end. Slip it through the copper tube from the bottom and bend the wire 90-degrees on the other side of the copper tube so the long side is towards the "Top" (see the picture--the long side will connect with the servo).

To attach the servo, first drill a 5/16" hole to expand the second hole from the end of the servo arm (see picture). Cut the tabs/wings off of the servo using the dremel so we can mount it flush to the plywood. Bend the copper wire toward where the servo will mount (see the picture) and hot-glue the servo to the plywood so that the axis of the hole in the copper tube lines up with the axis of the servo. You may need to adjust the servo glue point so that these line up correctly. Point the servo arm up (this is important as it'll be the starting orientation of the valve when closed)

Next, we need to cut down the knockout circle so that it will fit inside the copper tube. Use the dremel and metal file to make it the right size and shape. Be very careful when working with cutting tools and small metal. I NEVER hold the metal with my hand--use a G-clamp or something to attach it to a scrap piece of wood while cutting/filing. We will be using silicone to attach this "coin" to the copper wire making the valve. To do this, I put the coin on top of a makeshift stand (I used a foamcore block) to hold the coin snugly against the copper wire. The stand should be exactly the height from the edge of the panel to the copper wire. Then I put a good-sized blob of silicone on top of the coin right in the middle--make sure it doesn't reach the edges and rested the coin on top of the stand. Gently slip the coin up into the copper tube and rest the tube/panel/fan assembly on top for at least an hour so the silicone sets.

Step 7: Mount the Ethernet Jack

While the silicone is drying, you an attach a bit of jumper cable or other wire to the servo ends. Keep track of which wire attaches to the Brown (ground), Red (Power) and Orange (signal) cables. I used Cat 5 cable and lined Brown (Servo) - Brown (Cat5), Red (Servo) - White/Orange (Cat5), and Orange (Servo) - Orange (Cat5).

Cut the jumper cable to be about 6" long. Then on the other side, use the push-down tool to put the cables from the fan and the servo into the ethernet jack:

- Fan (Black) -- Pin 4 (GND)

- Fan (Red) -- Pin 5 (BLOW)

- Servo Brown (Cat5 Brown) - Pin 4 (GND)

- Servo Red (Cat5 White/Orange) - Pin 3 (+5V)

- Servo Orange (Cat5 Orange) - Pin 6 (SERVO)

After these are pushed down, put the cap onto the jack.

After the silicone dries, use hot glue to glue down the ethernet jack and the wires. Now plug the ethernet cable into the Ethernet jack on the custom PCB (Not the one on the Raspberry Pi!) and the other end into the jack you just assembled.

When you plug in the HeaterMeter, the should twist and the fan should turn on!

You will most likely need to configure your HeaterMeter servo. Log into the HeaterMeter configuration panel and adjust the servo settings to go from 950-1950. Put the HeaterMeter into Manual Fan Mode (see the Operation manual to see how) and bring the fan down to 0%. At 0%, the servo arm should be pointing straight away from the plywood. To adjust the servo, use a small screwdriver to pop the arm off and then point it the correct direction then pop it back on.

Mount it on the grill, mount the thermocouple into the hole in your grill, and you're ready to light 'er up.

You, my friend, are DONE! CONGRATULATIONS.

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6 years ago on Introduction

This is awesome. My wife and I just got a smoker (not a BGE) about a month ago. I bet she'll let me build this!

Great Instructable!