As the temperature drops it can become more difficult to keep your brew within the brewing temperatures that beer and wine kit manufacturers recommend, this helps to ensure a quick and thorough fermentation of your brew, and minimise the risk of any problems. This applies to all brews, beers, wines, lagers and cider. You need to take a few basic steps, brew away from draughts (hot and cold), if using a heating device then brew away from things such as radiators where the temperature will fluctuate and affect the heating device, and brew away from direct sunlight. Regardless of which type you opt for, it is very important to regularly check the temperature of your brew to ensure it is not too hot or cold, using an LCD self adhesive thermometer fixed to the outside of the vessel is often easiest. Fermentation will slow down and the time taken to ferment will increase in cooler temperatures, and if it is too cold, it will stop altogether. Try not to let the brew get too hot either, too warm and it may ferment more quickly, but there is the risk of it creating off flavours and killing the yeast if it gets too warm above the temperature the yeast can tolerate.

Consider using a heater device in conjunction with a timer if needed, temperatures are often lower on a night so it may be sufficient to have the heater set to apply heat at night only if the brew is getting too warm with it on constantly, or perhaps 2 hours on, 2 hours off etc. 

There are a few options and each has it's advantages and disadvantages, so here is a bit about each and when to use them;

The Immersion Heater - Home brew immersion heater for stable fermenting temperatures.

https://www.home-brew-online.com/electrim-te75-immersion-heater/

- Adjustable thermostat for accurate control of your brew
- Suitable particularly for glass demijohns and can be used in larger fermenting vessels such as our 25L vessel but is a little awkward to get the cable in/out. Please note that if an airtight fit is required with a fermenting vessel, a suitable hole for the bored 1 gallon bung would need to be drilled.

Low Wattage/Economical
Controlled Heat
Safe for Glass or Plastic Containers
Easy to clean
Heater On/Off Light

Limitations - The immersion heater MUST NOT touch the sides of the vessel. The thermostat can be set to various temperatures, but it can only heat the liquid by so much, if used in very cold conditions it will struggle, so insulating the vessel may be needed. As with all heating devices it is important to regularly monitor the temperature of your brew.

Better Brew heating pad- This heater pad is permanently on and gives off a constant warm gentle heat so it is important that regular checks should always be made to ensure that the correct temperature is being maintained.

Suitable for use with 23 Litre & 33 Litre Fermenting vessels and 5 gallon kegs and smaller with a flat base

The Heat Pad has a 30cm diameter.

About the Heating Pad:

Easy to use
Economical
Suitable for all Beer, Lager, Cider and Wine making
Effective
Double Insulated and complete with fitted mains UK plug

25 Watt - 240V 50z

https://www.home-brew-online.com/better-brew-flexible-heater-pad/

Limitations - The Heater Pad is continually on, it has no thermostat or control and requires monitoring from time to time to check the temperature. How effective it is will depend on the volume of liquid and the temperature of the room being brewed in.

The Brew Belt - a heated 'belt' which wraps around brewing vessels
http://www.home-brew-online.com/equipment-c40/better-brew-heater-belt-p1720

The Brew Belt can be used to aid fermentation with one or two demijohns or any make of 5 Gallon/25 Litre vessel and is suitable for both beer and wine making. It is designed to be used during primary fermentation and to aid the start of secondary fermentation.

The heat can be regulated by moving the Brew Belt higher or lower on the vessel. If it needs to be warmer lower the belt, if it is getting too warm, slide it up the outside of the vessel.

The Brew Belt is cheaper than heater trays, but has no thermostat and remains on constantly.

About the Brew Belt
Fits around any 5 Gallon Fermenter or two Demijohns
Easy to use
Economical
25 Watts / AC 230v / 50Hz
Made in England

https://www.home-brew-online.com/better-brew-heater-belt/

Limitations - The Brew Belt is continually on, it has no thermostat or control and requires manually positioning at the right height to get the temperature of the brew where you want it.

Standard Heater Trays - available in several sizes which vessels simply sit on;

25 litre suitable for fermenting vessels (TE25) - https://www.home-brew-online.com/electrim-heating-tray-25ltr-model-te25/

1 Demijohn tray - https://www.home-brew-online.com/electrim-heating-tray-1-demijohn-te1/

2 Demijohn tray - https://www.home-brew-online.com/electrim-heating-tray-2-demijohn-te2/

Heater trays are designed for the size of vessel you are brewing in, 1 demijohn, 2 demijohn and 25 litre fermenting vessel. They are constructed to withstand the weight of larger vessels and with the correct power output. They are thermostatically controlled to maintain a liquid temperature approximately 8 or 9 degrees C above ambient room temperature, giving a fermenting temperature of 22-29 deg C in most domestic environments. If brewing smaller batches than 23 litres the heater tray will still apply enough heat for a full batch, so you will need to check on the temperature to ensure it doesn't get too hot. 

Heater trays can also be used to stand a barrel or bottles on to keep the temperature up for the first few days of secondary fermentation, a 25 litre tray holds around 20 x 500ml PET plastic bottles at once.

The most popular size is the TE25 which hold up to a 25 litre vessel, as it can also be used to stand smaller vessels on, such as 1 or 2 demijohns.

Low Wattage/Economical 230 volts 25 watts
Controlled Heat
Thermally Insulated Base
Safe for Glass or Plastic Containers
Easy to clean
Heater On/Off Light
Size: 32cm

Limitations - If the room temperature is in excess of 20 degrees C (during the day for example) the heater should be switched off. Regular checks should always be made to ensure that the correct temperature is being maintained. If your vessel is only part filled such as when making a small batch, the heater will still apply the same amount of heat as though it was a full vessel, so small batches may become too warm so please regularly check the temperature.

A great set-up is to use a heater pad in conjunction with a thermostat controller that controls the heater so it only comes on when needed and turns off when it is at the correct temperature, the heater and thermostatic controller here on this link below are ideal and are supplied complete with a temperature probe, helping you to keep your brew at just the right temperature:

https://www.home-brew-online.com/mangrove-jacks-dual-temperature-controller/

https://www.home-brew-online.com/better-brew-flexible-heater-pad/

GENERAL NOTE - Always monitor the temperature from time to time to be sure how effective the heater is being as results can vary. Any heating device has its limitations, if brewing in a very cold place such as in a shed or garage, often home brew heating devices will not be able to keep the liquid warm enough. You may decide to insulate the vessel by carefully insulating it (by wrapping it up etc) so that less heat escapes and this helps the device to keep the liquid warm. The manufacturers do not recommend this though and care must be taken. If you do decide to insulate the vessel, it is very important to make sure that you do so safely, and that you regularly monitor the temperature that the brew is at using a thermometer. Brews can be harmed by getting too hot as well as too cold, so be sure to check on them, especially if the air temperature is regularly changing.