What a dry-herb vaporiser is
A dry-herb vaporiser is a device that heats dried medicinal cannabis flower to a controlled temperature in order to release its compounds as an inhalable vapour, without burning the plant material. The flower is placed in a heating chamber, the device brings that chamber to a set temperature, and the user draws air through it to inhale the vapour that is produced.
In Australia, when a patient is prescribed dried flower, it is intended to be vaporised in a suitable device rather than smoked. Vaporisers vary in form from larger desktop units that sit on a bench to portable handheld devices that can be used away from home, but the underlying principle of controlled heating is the same across designs.
Vapour, not smoke
Smoking relies on combustion — burning — which occurs at high temperatures and produces smoke containing combustion by-products. Vaporisation instead uses controlled heat held below the point of combustion (generally up to around 230 °C) so that the active compounds in the flower are released as vapour while the plant material itself is not set alight.
This distinction is the core reason a vaporiser is used in place of smoking: the device is designed to reach a temperature high enough to volatilise the compounds in the flower, but not so high that the material combusts. For a fuller comparison of the two processes, see the related article on medical cannabis vaporisation vs smoking.
Conduction vs convection heating
Dry-herb vaporisers generally use one of two heating methods, or a combination of both.
Conduction heats the flower through direct contact with a heated surface or chamber wall. The material sits against the hot surface and warms up from that contact. Conduction is simple and tends to heat quickly, but because the heat is uneven across the chamber it can heat the material unevenly and risks scorching the flower closest to the surface if it is not managed carefully.
Convection heats the flower by drawing heated air through it rather than by direct contact. The air is warmed first and then passes through the chamber, transferring heat to the material as it moves. This tends to heat the flower more evenly and generally gives more even extraction across the chamber. Many devices use a combination of conduction and convection to balance speed and evenness. Neither method is presented here as better for any individual patient — that is a matter for the device design and the user's own guidance.
Why temperature control matters
Temperature and time together affect which compounds volatilise from the flower and in what proportion. Lower temperature ranges tend to favour the more volatile aroma compounds such as terpenes, while higher ranges release more of the heavier compounds. Because of this relationship, precise and stable temperature control gives more consistent results from one session to the next.
This is general device science, not a dosing instruction. The appropriate temperature for any patient should follow the temperature guidance given by the prescribing healthcare practitioner and the device Instructions for Use. For a general overview of how temperature ranges are discussed, see the therapeutic cannabis vaporiser temperature guide.
The airpath and mouthpiece
The airpath is the route that air and vapour travel through the device. When the user draws on the mouthpiece, air is pulled through the heated chamber, where it picks up the vapour released from the flower. The vapour then travels along a cooling path before reaching the mouthpiece, which gives it a chance to cool before it is inhaled.
Materials used in the airpath should be suitable for inhalation, and medical-grade devices use materials that have been assessed for biocompatibility. Because vapour passes through the chamber, cooling path, and mouthpiece, these parts need routine cleaning to keep the airpath clear and functioning as intended; for general guidance on this, see the related cleaning article.
Use with prescribed flower
Vaporisers of this kind are used with cannabis flower that has been prescribed by a healthcare practitioner under Australia's access pathways. The device and the medicine are regulated separately from one another. For device choice and regulatory status, a device may be ARTG-listed as a medical device — for example, the Grenco Medical Elite II is ARTG Entry 526764, Class IIb.
Patients should follow the device Instructions for Use and the guidance of their prescriber for how the device is set up and operated. This article describes how the technology works in general terms only and does not make any claims about outcomes.