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Fluke · Fluke 62 Max+ Infrared Thermometer (Not for Human Temp), -20 to +1202 Degree F Range
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A non contact infrared thermometer for surface temperature on electrical, mechanical, HVAC and automotive equipment, reaching 650 C at the top of its range, with dual rotating lasers that mark the edges of the measurement spot, minimum, maximum, difference and average readings, and an IP54 rating against dust and splashing liquid. The top of the range is unambiguous. The bottom of it appears three times in this listing in three forms that cannot all be right, and the accuracy statement covers only the part above zero.
The bottom of the range appears three times and never agrees
Three figures describe the cold end of this instrument.
- The product name gives minus 20 F.
- The measurement bullet gives 30 degrees C.
- The same bullet, in the same sentence, gives 22 degrees F.
Convert them and the problem is immediate. Fahrenheit is Celsius multiplied by nine fifths with 32 added, so 30 C is 86 F, not 22 F. The pair inside the bullet does not convert. Meanwhile minus 30 C is exactly minus 22 F, which converts perfectly, and that is almost certainly what the bullet was meant to say before the minus signs were lost somewhere in the publishing chain.
The same thing has happened to the accuracy clause, which reads accuracy of or 1 degree C or or 1.0 percent of the reading. The word or appears where a plus and minus symbol should be. Once you have spotted that, the lost minus signs in the range stop looking like a contradiction and start looking like a transcription fault.
That still leaves the product name two degrees Fahrenheit away from the reconstructed bullet, minus 20 against minus 22. It is a small discrepancy, and it sits on the figure that determines whether the tool covers refrigeration temperatures. The top end, 650 C and 1202 F, converts exactly in both places and can be relied on.
The accuracy statement starts at zero degrees
Read the accuracy clause carefully and it carries an interval: one degree C or one percent of the reading, from 0 to 650 degrees C.
So whatever the true bottom of the range is, the specified part of it begins at freezing. Everything below that is inside the measurement range and outside the accuracy statement.
This is not a trick. Infrared measurement is genuinely harder as targets get colder, because the radiated energy the detector is working with falls away steeply with temperature, and a tolerance that holds comfortably at 400 C will not hold at minus 10 C. Specifying only the interval you can guarantee is more honest than quoting one figure across the whole span.
It does, however, determine who this instrument suits. The four applications named in the first bullet are electrical, mechanical, HVAC and automotive. Three of those live above zero almost all the time. The fourth does not: evaporator coils, suction lines, cold rooms and frozen stock are the cold side of HVAC work, and that is the region with no published tolerance. If sub zero readings are the reason you want it, get the figure before you buy.
No distance to spot ratio, which outranks the lasers
The lasers get a bullet of their own. The specification that governs what they are showing you does not appear at all.
An infrared thermometer averages everything inside a cone, and the distance to spot ratio tells you how wide that cone is at a given standoff. At 12 to 1, measuring from 600 mm gives a circle 50 mm across. At 30 to 1 the same standoff gives 20 mm. Those two instruments do different jobs, and nothing in these five bullets tells you which one this is.
It matters most on exactly the work the listing names first. An overheating terminal in a distribution board may be 10 mm wide. If the measurement spot is 50 mm, the reading is a blend of the hot terminal and the cooler metal around it, and the hot spot is understated. People conclude a connection is fine when it is not, and the aiming lasers do not protect them from it, because the lasers only show where the spot is once you know how big it is.
Two other absences belong beside it. There is no emissivity statement anywhere in the bullets, which is the largest error source in infrared measurement and the reason a shiny copper busbar reads cold. And there is no response time, which sets how quickly a sweep can be taken. Our page on emissivity explains why a bare metal reading is the one to distrust.
DIF and AVG are the readings that do the diagnostic work
The fourth bullet lists minimum, maximum, the difference between two temperatures, and the average. That set is better than it looks, and DIF is the member that earns the page.
Diagnosis with a surface thermometer is rarely about an absolute number. It is about a comparison: this phase against the other two, this bearing against its pair, supply air against return air, one radiator against the next. A differential is also structurally more trustworthy than a single reading, because an emissivity error or a spot size error that affects both measurements largely cancels when you subtract them.
MAX does the other half of the work. Sweeping along a row of connections while the instrument holds the highest value found means the hot one announces itself, rather than needing to be aimed at individually. AVG is for surfaces that are not uniform, where a single point is misleading.
IP54 rounds it out, and the listing states it precisely: protection against dust and splashing liquid. That is a plant room and engine bay rating, not an immersion rating, and the bullet does not pretend otherwise. Compare the approach of a thermal camera against a spot thermometer if you need to see a pattern rather than read a point.
Published figures against a refrigeration job
| Specification | Published in the listing |
|---|---|
| Measurement | Non contact surface temperature |
| Top of range | 650 C, given as 1202 F, consistent in both places |
| Bottom of range, product name | Minus 20 F |
| Bottom of range, bullet | 30 degrees C, given as 22 degrees F, which do not convert |
| Accuracy | 1 degree C or 1.0 percent of reading, from 0 to 650 C |
| Accuracy below 0 C | Not stated in the listing bullets |
| Aiming | Dual rotating lasers marking the edges of the spot |
| Readings | Minimum, maximum, difference, average |
| Ingress protection | IP54, dust and splashing liquid |
| Named applications | Electrical, mechanical, HVAC, automotive |
| Distance to spot ratio | Not stated in the listing bullets |
| Emissivity setting | Not stated in the listing bullets |
| Response time | Not stated in the listing bullets |
| Spectral response | Not stated in the listing bullets |
| Display resolution | Not stated in the listing bullets |
| Drop rating | Not stated in the listing bullets |
| Battery type and life | Not stated in the listing bullets |
Set that table against a refrigeration service call and the shape of the problem is clear. The temperatures of interest run from roughly minus 30 C to perhaps 60 C. The published accuracy covers the top two thirds of that window and says nothing about the bottom third. The spot size, which decides whether you are reading a suction line or a suction line plus its insulation, is absent.
Set the same table against a panel survey or an exhaust manifold and it reads differently. Everything of interest is well above zero, the one percent of reading term is comfortable at those temperatures, and the differential functions do the diagnostic work. The instrument is specified for hot work and under specified for cold.
Buy it for hot work, settle the cold end in writing first
For electrical, mechanical and automotive temperature checks above freezing, this is a well chosen feature set. A specified tolerance across a wide hot range, edge marking lasers instead of a single dot, a differential reading and a stated ingress rating together describe an instrument meant for working conditions rather than a specification sheet. Our infrared thermometer comparison puts the category side by side.
For anyone whose work is mostly below zero, two things need resolving first: the actual bottom of the range, which the page states three incompatible ways, and the accuracy below freezing, which it does not state at all. Both are answerable from the manual, and neither should be guessed at.
And for everyone, find the distance to spot ratio before the first survey. It is the difference between a reading that describes a fault and a reading that describes a neighbourhood.
Recommended Tools
Products shown because their documented specifications fit this guide. Price and availability are on Amazon and can change.
Frequently Asked Questions
Which low temperature figure should a buyer believe?
None of them, until it is confirmed. The product name says minus 20 F. The bullet says 30 degrees C and 22 degrees F in the same sentence, and those two do not convert into each other, since 30 C is 86 F. The only reading that makes the bullet internally consistent is minus 30 C and minus 22 F, which do convert. That still leaves the name and the bullet two degrees Fahrenheit apart at the bottom, so the low end needs to come from the manual rather than the page.
Why does the accuracy figure only cover 0 to 650 C?
Because that is the interval the manufacturer is prepared to specify, and an unspecified part of a range is not the same as an unusable one. Infrared measurement gets harder as the target gets colder, since the energy being measured falls steeply with temperature, so a tolerance that holds at 400 C will not hold near freezing. The practical effect is that readings below zero are indicative. For anyone checking evaporator coils, cold stores or frozen goods, that is the whole job.
What is a distance to spot ratio and why does its absence matter?
It is the relationship between how far you stand from a target and how wide an area the instrument averages. A ratio of 10 to 1 means that at 500 mm the reading covers a circle 50 mm across. Without it you cannot know whether a reading describes the terminal you aimed at or that terminal plus the busbar and the enclosure behind it. On an infrared thermometer it is arguably the most consequential single specification, and this listing does not publish it.
What do the two lasers actually show?
The bullet says they rotate to pinpoint the edges of the measurement area, which is a more useful design than a single aiming dot. A single dot tells you where the centre is and invites the assumption that the dot is the measurement. Two rotating lasers describe the boundary of the circle being averaged, so you can see whether a hot connection fills the spot or occupies a small part of it. It is the difference between aiming and framing.
Why does the name say not for human temperature?
Because a surface thermometer of this class is built for the wrong problem. The range reaches 650 C and the accuracy is quoted as one degree C or one percent of reading, which is coarse next to the fractions of a degree that matter clinically. Skin emissivity, sweat, ambient draughts and the measurement spot size all add further error. Printing the warning in the product name rather than in small print is the right call.
What are MIN, MAX, DIF and AVG for?
They convert a single reading into a comparison. Sweeping across a row of terminals and reading MAX finds the hottest without needing to watch the display. DIF reports the gap between two temperatures, which is how a differential is read across a heat exchanger, across phases of a panel or between a running bearing and its neighbour. AVG smooths a noisy surface. A differential is also far more robust than an absolute figure, because errors common to both readings largely cancel.
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