In most fermentation cases you do.
Even if you only use it for 3-4 months of the year and only at night it is still a worthwhile investment.
Our copper tun heater pads are 25 watts there fore they don’t use a great amount of electricity. Depending on where you live will determine how frequently you will need to use your heater pad. In some cooler areas you may need to use them 24 hours a day but this is highly unlikely in most of Australia.
The majority of people only need to turn them on in the afternoon and off again in the morning and you do not need to use them in the first 24 – 48 hours of fermentation. During this time the activity created by the yeast and sugar will create enough of its own heat.
Because they heat evenly across the bottom the heat then rises evenly through your wash or wort. This will give you a more pleasant tasting end result. Any fluctuations that occur during the fermentation process can produce some unpleasant tastes.