Heating Up A Fermenter

TroubleShooting

Luiz-Roberto Reboucas — São Paulo, Brazil asks,

Living in southeast Brazil (São Paulo State) I enjoy nice temperatures during the entire year. It ranges from 10 °C (50 °F) in the night during severe winters to 35 °C (95 °F) in the hottest summer. Being a homebrewer brewing 20-L (5.25-gal.) batches, I took over an old chest freezer and adapted it to accommodate my plastic conical fermenter (21-L/5.5-gal. capacity). The fermenter has an appropriate port for a temperature probe, and I use this information to control my chest freezer temperature. This normally poses no problems with lagers. However, when brewing ales in the wintertime, it is sometimes difficult to stabilize the temperature during the night; for example, required fermentation temperature is 20 °C (68 °F) and at night the temperature goes down to 12 °C (54 °F). The chest refrigerator´s insulation helps a little and the temperature only drops down to ~16 °C (61 °F). What should I do?