The technology inside your leak detector matters more than most techs realise. Two detectors can look almost identical, carry similar price tags, and both claim to find refrigerant leaks — but one uses a heated ceramic element that degrades with use, and the other uses an optical sensor that measures infrared light absorption.
Those aren't minor engineering differences. They produce different sensitivity levels, different false-alarm profiles, different maintenance schedules, and different total ownership costs over a three-to-five year service life.
If you've ever walked away from a job confident a system was clean, only to get a callback two weeks later, the technology in your detector may have been part of the problem.
This guide explains how each type works in plain terms, compares them directly, and gives you a straight answer on which technology suits which type of Australian HVAC work. Browse our electronic leak detectors across both heated diode and infrared technologies while you read.
Reviewed by Rica Francia Macaspac | Published: May 2026 | Last reviewed: May 2026
How Heated Diode Detectors Work
Heated diode detection is the technology that built the professional HVAC leak detector market. It's been the dominant approach for decades, and for good reason — it works, it's affordable to manufacture, and it's sensitive enough for the vast majority of residential and light commercial refrigerant leak scenarios.
At the core of a heated diode detector is a small ceramic element — sometimes called the sensor tip or sensing bead — that is electrically heated to a high temperature. Air is drawn across this element by a small pump inside the detector.
When that air contains a halogen-based refrigerant — any of the common HFC or HCFC gases used in Australian HVAC systems — a chemical reaction occurs on the heated element. Halogen atoms from the refrigerant react with the ceramic material in a way that changes its electrical resistance.
The detector's circuitry measures that resistance change and translates it into an alarm signal: a beep, a chirp, or a rising tone, depending on the model.
The sensitivity of a heated diode detector is generally very good for HFC refrigerants like R-410A and R-32 — the two most common refrigerants in Australian residential and commercial split systems right now.
R-32 in particular is increasingly common in newer systems due to its lower global warming potential. It contains halogen atoms that react readily with a properly maintained heated diode sensor. For a tech servicing residential splits in Melbourne or commercial multi-splits in Brisbane, a quality heated diode unit with a fresh tip will find the leaks you need to find.
Refrigerant compatibility is worth understanding before you buy. Heated diode sensors are designed for halogen-based refrigerants — HFCs, HCFCs, and HFOs. They are not suitable for detecting natural refrigerants like CO2 (R-744) or ammonia (R-717), which require entirely different sensing technologies.
If you're working on NH3 systems in a QLD cold store or a CO2 transcritical system in a modern supermarket, a standard heated diode unit will not help you. Confirm the refrigerant type on any system before selecting your detector.
The Inficon TEK-Mate is the most widely recognised heated diode detector in the Australian market. It's compact, straightforward, and handles the common HFC refrigerants reliably.
The sensor tip is user-replaceable — this is the defining maintenance characteristic of heated diode technology. When the tip degrades, sensitivity drops, and you may not immediately notice.
A worn tip can give you a weak or absent reading on a system that is actively losing refrigerant. The practical consequence is a missed leak, a completed job card, and a client who calls back three weeks later wondering why their system is low on gas again.
Replacing the tip on schedule — not just when the detector seems off — is the most important maintenance habit for any heated diode user. Keep spares in the van.
How Infrared Detectors Work
Infrared leak detection takes a completely different approach to finding refrigerant. Instead of a chemical reaction on a heated element, it uses optical spectroscopy — measuring how much infrared light is absorbed by the air sample passing through the detector's sensing chamber.
Every molecule absorbs infrared light at specific wavelengths determined by its chemical structure. Refrigerant molecules are no exception.
An infrared detector contains a light source that emits IR radiation, a sensing chamber through which the sampled air is drawn, and a detector on the other side that measures how much IR light gets through.
When refrigerant is present, it absorbs IR light at its characteristic wavelengths. The detector registers that absorption as a reduction in signal. The greater the refrigerant concentration, the greater the absorption, and the stronger the alarm response.
This spectroscopic approach has two significant practical advantages over heated diode technology.
First, sensitivity is generally higher. Infrared detectors can detect lower concentrations of refrigerant than comparable heated diode units. For very slow leaks on large commercial systems — the kind that show up as a 200-gram shortfall on a 10-kilogram charge over six months — this sensitivity difference can be the difference between finding the leak on the first visit versus the third.
Second, selectivity is considerably better. An infrared detector is tuned to the specific IR absorption profile of refrigerant gases. Cleaning products, paint fumes, exhaust gases, and other ambient chemicals that routinely trigger false alarms in heated diode units don't absorb IR light at the same wavelengths as refrigerant, so the infrared detector ignores them.
The spectroscopy principles behind infrared leak detection align with standards referenced by bodies like ASHRAE, whose technical guidelines inform how HVAC/R equipment is evaluated for performance and application suitability.
Understanding those underlying principles helps you make sense of why sensitivity and selectivity ratings differ between technologies, and why the spec sheet numbers matter when comparing models.
In practical Australian terms, the false-alarm advantage is significant. A tech probing valve cores in a commercial kitchen in Darwin — working around cleaning chemicals and cooking fumes — encounters far fewer nuisance alarms with infrared than with heated diode.
The same applies in hospital plant rooms in Sydney where solvents and disinfectants are present. False alarms slow you down. On time-and-materials jobs they cost productivity. On fixed-price commercial contracts, every unnecessary alarm costs real money.
The Fieldpiece DR82 and SRL2 are the most widely discussed infrared detectors in the Australian market. The DR82 sits in the mid-range and suits busy commercial service techs who want infrared advantage without the top price tier.
The SRL2 is Fieldpiece's advanced infrared option, offering higher sensitivity for the most demanding applications. Neither has a consumable sensor element that degrades with use — which is the operational difference that defines infrared's long-term value over heated diode.
Technology Comparison Table
The table below compares heated diode and infrared technology across the practical factors that matter most for day-to-day HVAC/R work. Sensitivity and sensor life figures are indicative — always confirm the current datasheet for your specific model, as manufacturers update these with hardware revisions.
| Feature | Heated Diode | Infrared |
|---|---|---|
| Detection principle | Chemical reaction on heated ceramic element | IR light absorption (spectroscopy) |
| Typical sensitivity | ~5 g/year equivalent (varies by model — confirm datasheet) | ~1 g/year equivalent (varies by model — confirm datasheet) |
| Selectivity | Moderate — susceptible to false alarms from competing chemicals | Excellent — tuned to refrigerant IR profile |
| Sensor lifespan | Consumable tip — typically 100–200 hours, shorter under heavy use | No consumable element — significantly longer operational life |
| Refrigerant compatibility | HFCs, HCFCs, HFOs (halogen-based). Not suitable for CO2 or NH3 | HFCs, HCFCs, HFOs. Some models also detect HFOs and A2L gases — confirm datasheet |
| R-32 / A2L suitability | Generally compatible — confirm model spec | Generally compatible — some IR models offer enhanced A2L detection |
| False alarm resistance | Moderate | High |
| Entry price point | Lower | Higher |
| Ongoing maintenance cost | Higher — regular tip replacement required | Lower — minimal consumables |
| Typical application | Residential splits, light commercial, apprentice first buy | Commercial HVAC, refrigeration, high-chemical environments |
| Example models (AU) | Inficon TEK-Mate, Fieldpiece SRL8 | Fieldpiece DR82, Fieldpiece SRL2, Inficon D-TEK Stratus (dual mode) |
Sensitivity figures expressed as grams per year equivalent represent the minimum leak rate a detector can reliably identify under controlled conditions. Real-world sensitivity can vary with probe technique, ambient temperature, airflow conditions, and sensor condition. Always treat published sensitivity figures as a starting point and confirm current specs on the manufacturer's datasheet before purchase.
Heated Diode Advantages
Heated diode technology isn't the old option that infrared has made obsolete — it's a proven technology that continues to be the right choice for a large portion of the Australian HVAC/R market. Understanding why helps you make a smarter buying decision.
Cost of entry is the most obvious advantage. A quality heated diode detector costs significantly less upfront than a comparable infrared unit.
For an apprentice making a first tool purchase, a sole trader starting out, or a business equipping a larger service team, that price difference matters. An apprentice who develops correct probe technique on a well-maintained heated diode unit is better prepared to use any detector accurately than one handed an expensive infrared unit they don't yet know how to use.
Proven technology is an underrated advantage in the trade. Heated diode detection has been used in professional HVAC/R work for long enough that its behaviour is well understood by experienced technicians, parts suppliers, and distributors who stock replacement tips.
When something goes wrong — or when sensitivity drops and you're not sure why — there's a large body of practical knowledge in the trade to draw on. The failure modes are predictable: the tip wears out, it gets saturated by high-concentration exposure, or it gets contaminated. Those are fixable problems with known solutions.
Wide availability of both units and replacement parts is a practical consideration in Australia, particularly outside the capital cities. If you're based in regional QLD, rural WA, or anywhere not within easy reach of a major trade supplier, knowing that heated diode tips are stocked by multiple distributors matters.
Some infrared models have longer lead times on service parts or require returning the unit for servicing — confirm parts availability with your local supplier before committing to any model.
For residential work, a heated diode detector handles the job reliably. You're servicing split systems, multi-head units, and light commercial equipment where refrigerant volumes are modest and the work environment is relatively clean.
Most residential refrigerant leaks occur at flare joints, valve cores, or brazed connections stressed by vibration or poor installation. These are detectable with a quality heated diode unit and good technique. There's no practical need to spend $600–$800 on infrared technology if your day is five residential service calls in suburban Adelaide or Hobart.
Familiarity is a genuine operational advantage. A tech who's been using a heated diode detector for several years knows exactly how it responds — how the alarm changes as you get closer to a leak, how it behaves in different ambient conditions, what a false alarm feels like versus a real hit.
That built-up pattern recognition has real value on the tools. Switching technology means relearning those cues, which takes time and can introduce diagnostic errors during the transition period.
Infrared Advantages
For a growing segment of Australian HVAC/R work — particularly as systems get larger, refrigerants get newer, and clients expect more rigorous documentation — infrared technology offers advantages that heated diode simply can't match.
Higher sensitivity is the headline advantage. Infrared detectors can reliably detect lower refrigerant concentrations than comparable heated diode units.
That sensitivity stays consistent over the tool's service life because there's no consumable element degrading with use. On a large VRF system in Sydney's CBD, or a supermarket rack system in a Melbourne distribution centre, a slow leak that loses 200 grams over six months is a real problem.
Finding that leak on the first inspection rather than the second or third is the practical value of higher infrared sensitivity. It matters for the client's running costs, for refrigerant compliance obligations, and for the system's long-term reliability.
False alarm resistance makes infrared the better choice for complex environments. Heated diode sensors respond to any halogen-based chemical — not just refrigerant.
In environments with cleaning products, adhesives, paint fumes, or exhaust gases, this creates nuisance alarms that slow down a job and erode confidence in the tool. An infrared detector tuned to refrigerant's specific IR absorption profile is largely immune to these competing chemicals.
The consequence of this advantage is real: fewer false alarms mean faster diagnostics, cleaner job records, and less time explaining to a building manager why the alarm keeps going off near the cleaner's cupboard.
Longer sensor life is where the total ownership cost argument for infrared gets most compelling. A heated diode unit needs tip replacement every 100–200 hours of operation — more frequently if tips are exposed to high-concentration refrigerant.
The labour time to source and fit replacement tips adds up over a two-to-three year service period. An infrared detector with no consumable element doesn't have that ongoing cost.
The upfront price premium for infrared narrows considerably when you factor in three years of tip replacement costs for a comparable heated diode unit. It disappears entirely if you're running a fleet of detectors across multiple technicians.
R-32 and A2L refrigerant suitability is increasingly important in the Australian market. R-32 is now the dominant refrigerant in new residential split systems.
A2L refrigerants more broadly are becoming common as the industry moves away from higher-GWP options under regulatory pressure. While most quality heated diode detectors handle R-32 adequately, some infrared models are specifically optimised for A2L detection sensitivity.
These have been validated against the specific IR absorption characteristics of these newer gases. If you're servicing a significant volume of new R-32 equipment — particularly in high-turnover residential markets like Brisbane's new apartment stock or Perth's growth corridors — confirming your detector's A2L optimisation is worth doing.
Check the model's datasheet or ask your distributor directly.
R-32 is classified as an A2L refrigerant — mildly flammable under specific conditions. While leak detection for R-32 uses the same electronic detector approach as other HFC refrigerants, safe handling of R-32 systems requires awareness of its flammability classification. ARCtick-licensed technicians working on R-32 systems should be familiar with the relevant safe work guidelines. Safe Work Australia publishes guidance on handling flammable refrigerants that's worth reviewing if A2L systems are a growing part of your workload.
Which Technology for Your Work?
The honest answer is that both technologies work — the question is which one works best for how you actually spend your days on the tools.
For residential split system work, a heated diode detector is entirely sufficient. The leaks you're finding are at predictable locations — flare connections, valve cores, Schrader valves, brazed joints on indoor and outdoor units — and the refrigerant volumes are modest.
A quality heated diode unit like the Inficon TEK-Mate with fresh tips and correct probe technique will find these leaks reliably. The economics are straightforward: lower upfront cost, easy parts access, and a tool that matches the job complexity you're dealing with. Don't overthink it.
For commercial HVAC contractors — VRF systems, large commercial splits, air handling units, plant rooms — infrared is the recommended technology. The system complexity is greater, the refrigerant charges are larger, the environments are more chemically contaminated, and the cost of a missed leak is higher.
The Fieldpiece DR82 is a well-regarded mid-range infrared option for this work tier in Australia. The Inficon D-TEK Stratus offers dual-mode operation — heated diode for speed and infrared for confirmation — which suits techs who want flexibility across different job types in a single tool.
For budget entry into professional leak detection, heated diode is the starting point for most Australian apprentices and early-career techs. Getting the technology right matters less at this stage than getting the technique right.
An apprentice who learns to probe slowly, sample at distance, and interpret alarm signals accurately on a heated diode unit is developing skills that transfer to any detector technology. HVAC School and similar platforms cover leak detection technique in practical detail for techs at any stage of their career.
For long-term value across a busy commercial service business, infrared makes financial sense even at a higher upfront cost. Run the numbers: three years of tip replacement on a fleet of four heated diode detectors adds up to a real cost figure.
Compare that to the upfront premium for infrared units with minimal consumable cost over the same period, and the total ownership calculation often favours infrared. Add the productivity benefit of fewer false alarms and the lower callback risk from higher sensitivity, and the business case is clear for any operation doing significant commercial volume.
Whatever technology you're running, pairing it with a quality set of electronic leak detectors appropriate to your refrigerant mix is the foundation.
From there, technique matters as much as technology — a great infrared detector used carelessly will miss leaks that a modest heated diode unit finds with correct probe discipline. Hvac's maintenance and tool selection guides on the HVAC Shop blog cover the broader picture beyond just the detector itself.
Get the Right Technology
Heated diode technology is proven, affordable, widely supported in Australia, and the right choice for residential and light commercial work where cost of entry matters and job environments are relatively clean.
Infrared technology offers higher sensitivity, better false-alarm resistance, longer sensor life, and lower total ownership cost for any operation doing volume commercial work. It costs more upfront and returns that premium over a two-to-three year service period through lower parts cost and fewer productivity-draining nuisance alarms.
If you're not sure which technology matches your specific refrigerant mix or work pattern, the HVAC Shop team can help you work through the decision before you commit.
Browse both heated diode and infrared options in our refrigerant leak detector collection — all models are Australian stock with genuine local warranty support — or get in touch if you want a direct recommendation based on the systems you service most.