Take temperature readings using an imaginary 6m x 6m grid over the bulk surface and take a reading in the centre of each grid square at 70mm and 300mm below the surface.
This means readings are always in the same place and shows actual changes rather than location differences.
In boxes, place sensors in stacks at the edge and centre and in the top and bottom box 70mm and 300mm from the surface.
Record the potato temperature readings at least once per week until the potatoes have been cooled to the target storage temperature; and then every two weeks thereafter.
This is the minimum requirement.
The more comprehensive and the more frequent that temperature monitoring takes place, the better the chances of good store management.
Manual readings should ideally be taken daily; automatic readings should be 3-hourly in the potatoes and continuous for ambient temperature.