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TempPro · TempPro TempScan Infrared Thermometer Gun for Pizza Oven Griddle HVAC
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A thermopile infrared thermometer with stated accuracy of plus or minus 1.5 percent, emissivity adjustable from 0.1 to 1.0, a 12 to 1 distance to spot ratio, a response time under 500 ms, a range of minus 58 F to 1022 F, MAX, MIN and AVG of the last scan, and a backlit screen with a 90 second auto off. Two of those specifications decide whether a reading is true rather than merely repeatable, and this listing publishes both.
The spot ratio is the specification nobody reads
An infrared thermometer does not measure a point. It collects radiation from a cone, and where that cone meets the target it forms a circle. The reading is the average temperature across the whole circle.
The distance to spot ratio tells you how big the circle is. At 12 to 1, the circle diameter is one twelfth of the distance.
| Distance to target | Measured circle at 12 to 1 | What the reading averages |
|---|---|---|
| 12 inches | 1 inch | A single terminal or a small component |
| 3 feet | 3 inches | A component plus its neighbours and air gaps |
| 6 feet | 6 inches | A section of panel, mostly enclosure |
| 20 feet | 20 inches | Most of a wall |
This is where infrared readings go wrong, and it goes wrong in a specific direction: the reading is always pulled toward the temperature of the surroundings, so a hot target measured from too far away reads cooler than it is. You conclude there is no problem.
The laser makes this worse by looking like a point. A single dot in the middle of a six inch averaging circle gives every impression that you measured the dot.
So the practical rule that follows from 12 to 1 is: get within twelve times the size of your target. A one inch terminal needs twelve inches. A four inch pipe tolerates four feet. A wall tolerates almost anything. If the geometry does not allow it, a spot thermometer is the wrong instrument and an imaging one is the right one.
It is worth saying that 12 to 1 is a decent ratio for this class. Cheap instruments are often 8 to 1 or worse, and professional ones reach 50 to 1 and beyond. The figure is only useful because it is published.
Adjustable emissivity is the other half
The listing states emissivity adjustment from 0.1 to 1.0 to match the surface material being measured.
Emissivity is the efficiency with which a surface emits infrared radiation compared with a perfect emitter. It is a property of the surface, not the temperature, and it varies far more than people expect.
Matt paint, brick, wood, fabric and food all sit around 0.9 to 0.95 and read close to true on an instrument set for them. Polished copper, aluminium and stainless steel can sit at 0.1 or below, which means they radiate almost nothing at their own temperature and what the thermometer mostly sees is the room reflected in them.
The error is large. A busbar at 80 C with an emissivity of 0.05, measured by an instrument assuming 0.95, can read closer to 30 C. That is not a small inaccuracy, it is a wrong answer that hides a fault.
An adjustment range down to 0.1 lets you enter the right value if you know it. More practically it lets you verify: put a patch of matt electrical tape on the metal, set emissivity to 0.95, wait for the tape to reach the metal temperature and read the tape. Instruments without the setting cannot do either.
Our page on choosing an infrared thermometer covers which surfaces need the correction most.
Range, response and the sweep function
The range of minus 58 F to 1022 F is wide, reaching from freezer temperatures to pizza oven and exhaust manifold territory. The listing mentions pizza ovens and griddles specifically, and at the top end that reach matters because cooking surfaces exceed what many instruments cover.
The response time under 500 ms is what makes the sweep usable. With MAX, MIN and AVG recorded from the last scan, you hold the trigger and move the instrument across a surface, and it returns the hottest point, the coldest point and the average of the pass.
That is a different technique from spot checking and a better one for finding problems. On a griddle you learn where the burner is actually heating. On a duct run you find the section that is losing heat. On a row of motors you find the odd one out. Taking twenty discrete readings and comparing them from memory is how that gets done without a sweep function, and it is both slower and less reliable.
The published specification
| Specification | Published in the listing |
|---|---|
| Accuracy | Plus or minus 1.5 percent |
| Emissivity | Adjustable, 0.1 to 1.0 |
| Distance to spot ratio | 12 to 1 |
| Response time | Under 500 ms |
| Range | Minus 58 F to 1022 F, minus 50 C to 550 C |
| Sensor | Thermopile |
| Readout | MAX, MIN and AVG of last scan, backlit LCD |
| Power management | Auto off after 90 seconds |
| Optimal measuring distance | Not stated in the listing bullets |
| Battery type | Not stated in the listing bullets |
| Repeatability | Not stated in the listing bullets |
One absence is worth naming because a competing instrument in this project does publish it: an optimal measuring distance. Infrared optics are focused, and there is usually a distance at which the spot is tightest and the reading best. Knowing it is useful. This listing gives the ratio but not the sweet spot.
The 90 second auto off is a small but real irritation to anticipate. On a job where you take a reading every few minutes, the instrument will keep switching itself off between readings.
Who should buy it
Buy this if you need surface temperatures you can defend and you can get close to your targets. The published accuracy, the adjustable emissivity and the stated spot ratio together mean you can reason about whether a reading is right, which is not possible with an instrument that publishes none of the three.
It will not help you find which component in a cluster is hot, because a spot thermometer averages and does not image. For that the right tool is an imaging instrument, even a very coarse one, and this project covers a 4,800 pixel unit that exists precisely for that job. And remember the geometry: a one inch target needs you within a foot, whatever the laser dot suggests.
Recommended Tools
Products shown because their documented specifications fit this guide. Price and availability are on Amazon and can change.
Frequently Asked Questions
What does a 12 to 1 distance to spot ratio mean?
That the circle the instrument measures is one twelfth of the distance to the target. At twelve inches away the circle is one inch across. At six feet it is six inches. At twenty feet it is twenty inches. The reading is the average temperature across that whole circle, not the temperature of the dot the laser lands on, and this is the single most misunderstood specification in infrared measurement.
So how close do I need to be?
Close enough that the circle is smaller than the thing you are measuring. For a one inch electrical terminal that means about twelve inches away or less. Standing back six feet to read a terminal gives you a six inch average that includes everything around it, which will read far cooler than the terminal. If you cannot get close, you need a narrower optic or a thermal camera, not a longer arm.
Why does adjustable emissivity matter?
Emissivity is how efficiently a surface radiates infrared, and it varies enormously. Matt paint is around 0.95 and reads nearly true. Polished metal can be below 0.1, radiating almost nothing at its own temperature while reflecting its surroundings, so a thermometer fixed at 0.95 can read a hot copper bar tens of degrees low. The listing states adjustment from 0.1 to 1.0, which lets you set the right value or tape the surface and read the tape.
Is plus or minus 1.5 percent good?
It is a reasonable figure for this class and the important thing is that it is published at all. Note that it is a percentage, so the absolute error grows with temperature: at 200 C it is about 3 degrees, at 500 C about 7.5. Several competing listings give no accuracy figure whatsoever, so comparison is impossible against those.
What is MAX, MIN and AVG of the last scan for?
Sweeping rather than spot checking. Hold the trigger and move across a surface, and the instrument records the extremes and the mean of everything it saw. On a griddle or a duct run that is how you find the hot and cold areas without taking twenty separate readings and trying to remember them.
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