Chantillac Vineyard – April 2021

Key Points

The vineyard area is sloping down from left to right (West to East) and from North to South.

François François-Xavier Cornette is using Heat Ranger to protect his grape vines in the Cognac Region and the picture above shows the location of the Heat Ranger machine and the masts for monitoring the temperatures at cordon height, and at 3m and 6m above ground level.
From initial temperature monitoring the coldest areas are at the top right corner at mast 200m and at mast 150m.

  • Heat Ranger’s objective is to protect crops by keeping the fruiting zone above damaging temperatures in frost events as cold as -3oC. While temperatures can drop, the new shoots can survive brief periods as low as 2°C provided that plants are not subjected to these low temperatures for more than about 10 to 15 minutes. The coldest area is the North East corner.
  • April has seen a number of serious frost events throughout France and current indications are that this is going to become the new normal temperature situation.
  • Attached are plots for three of the recent events showing the temperature and Heat Ranger response.

Individual Test Results

12 April 2021

This frost was saw temperatures declining towards midnight and then there was a brief increase in temperatures back up to 3°C before a continuous decline began about 1:30 a.m. The machine went through a warm-up cycle at 1:30 then turned off and restated at 2:25 when the temperature reached plus 0.5°C. The chart shows an immediate slowing down in the cooling rate at all four reference masts with the greatest effect at 50m and reducing with distance out to 200m. The coldest temperature reached was 2.7°C at the 200m mast but nowhere else dropped below –

Minutes below frost temperatures

17 April 2021

Temperatures dropped quite quickly after midnight and the machine switched on at +1°C but temperatures rose again and the machine switched off until restating at 6:15 as temperatures started to decline again and continued through until 8:40 with nozzle temperatures between 30 and 32°C. The response to the second start 6:15 is immediately obvious as the temperature decline is temporarily halted on the first 3 masts out to 150m, and can still be detected at 200m.

Minutes below frost temperatures

18 April 2021

Temperatures did not get down towards frost level until 4:00a.m. and the machine started and continued to 8:30. At the time of starting the 50m mast was the coldest which illustrates the big variability we can have in relatively short distances within a vine area. This makes it extremely difficult to establish a control temperature that is outside the target area.

Minutes below frost temperatures


The temperatures are recorded every minute while the machine is operating. When you look at the graphs you can see a temperature spike in the 50m and 100m masts as the nozzle goes past but this is more spread out further away. If an operator wants to have readings at shorter intervals, this can be adjusted over the internet connection. The turret rotates every 3 minutes and for the nearer masts the rise and fall within each three minute cycle can be seen, but further out the warm air is more spread out and uniform.


The Heat Ranger machine tends to have a range of between 180 to 250m but this can vary according to wind and topography. The location of the machine was as central as possible and on a slight angle to try and adjust for the land slope. It needs to be in a location suitable for access for the gas tanks to be changed.

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