According to skunkpharm, yes!
https://skunkpharmresearch.com/decarboxylation/
"When we heat cannabis to convert the THCA and CBDA into THC and CBD, we are also converting THC to CBN at a faster rate. At about 70% decarboxylation, we actually start converting THC to CBN at a faster rate than we are converting THCA to THC, so as you can see by the following graph, after about 70% decarboxylation, the levels of THC actually start to fall sharply."
The skunkpharm chart suggests about 40 minutes @ 240F for peak levels of thc and the nova is going 60 minutes @ 240F (plus heat up and cool down time). So, if skunkpharm is correct, then we all might see increased thc levels (along with thca and cbda levels) if we unplug the unit 60 minutes after turning it on (20 minutes to get up to 240F + 40 minutes @ 240F to decarb).
I was looking for decarb info and there is a lot out there in the form of patents. This is for plant matter, not concentrates.
https://www.google.com/patents/US8846409
"Preferably, decarboxylation is carried out in a multi-step heating process in which the plant material is:
i) heated to a first temperature for a first (relatively short) time period to evaporate off retained water and allow for uniform heating of the plant material; and
ii) the temperature is increased to a second temperature for a second time period (typically longer than the first time period) until at least 95% conversion of the acid cannabinoids to their neutral form has occurred.
Preferably the first step is conducted at a temperature in the range of from 100° C. to 110° C. for 10-20 min. More preferably the first temperature is about 105° C. and the first time period is about 15 minutes.
Optimum times and temperatures for the second step may vary depending on the nature of the plant material, and more particularly on the cannabinoid which it is intended to isolate from the plant material, and may be easily determined by routine experiment. Suitable conditions may include, for example, a temperature in the range of from 115° C. to 125° C. for a time period in the range of from 45 to 75 minutes (typically 120° C. for 60 minutes), or a temperature in the range of from 135° C. to 145° C., for a time period in the range of from 15 to 45 minutes.
If the plant material is derived from
cannabis plants having a high THC content (defined as >90% THC as a percentage of total cannabinoid content), the second temperature is preferably in the range of from 115° C. to 125° C., typically 120° C., and the second time period is preferably in the range of from 45 minutes to 75 minutes, typically about 60 minutes. More preferably the second temperature is in the range of from 100° C. to 110° C., typically 105° C., and the second time period is in the range of from 60 to 120 minutes. In another embodiment, most preferred for a mass of plant material greater than 4 kg, the second temperature is in the range of from 140° C. to 150° C., preferably 145° C., and the second time period is in the range of from 45 to 55 minutes.
Where the starting “plant material” is freshly harvested or “wet” plant material is may be subjected to a drying step to remove excess moisture prior to step (i). For convenience, decarboxylation and drying may be combined in a single heating step or in a multi-step heating process, as described above."