Running a beer cellar is something that calls for a certain amount of knowledge in order to produce a fine pint of beer at the tap, yet it is surprising just how many publicans do not fully understand everything that goes on down there.

One of the most important factors is the beer cellar temperature. This should be at 12°C (54°F). It can go a degree over or under - 13°C to 11°C – but no further. Before we invented refrigeration, brewers had to use underground cellars and caves in order to both brew the beer and to keep it cool enough in the summer. Too high a temperature will cause problems. When beer is bottled or kegged it contains carbon dioxide gas which is a preservative, and also has the effect of producing a nice head when the beer is poured. At the cooler temperatures the CO2 remains in solution, but at warmer temperatures it is released. When the beer is then opened or pulled the CO2 rapidly dissipates which causes the beer to foam out and then go flat. If there is yeast in the brew, as in bottle-conditioned beers, they can really take off and it is even possible to explode the bottle.

Another problem of beer cellar temperature that is too high is oxidation of malt flavours which gives the beer a bitter taste. Too much heat degrades the hop aromas as well, increasing the hop bitterness.

On the other hand, a beer cellar that is too cold can damage the yeast and produce a chill haze. You have to remember that yeast is a living thing and is affected very rapidly by too low a temperature. This also affects carbonation because as it gets colder the CO2 is absorbed in solution, and when a bottle is opened there may be virtually no fizz at all. Keeping the beer cellar at the correct temperature avoids all these problems.

Another thing is to keep minimal light in your cellar. A beer that is light-struck has a particularly unpleasant smell, sometimes described as "catty". It has been found that light degrades the hop oils in the beer which is what causes the problem. Of course, this is not a problem with cask beers, but certainly can affect bottled beer.

There are still many publicans who either completely fail to condition their cask beers, or if they do, don't get it right. A lot of people think that the beer is ready to serve when it is delivered, but that is not the case. It has to be stored to allow it to settle and to give enough time for the secondary fermentation to take place. This can vary between different beers, so it is important to follow the brewer's instructions to the letter. Indeed, many brewers put on their own courses in order that pub staff can learn how to ensure the beer gets to the customer in first class condition.

Another thing is that cask ale deteriorates three days after being opened because of exposure to bacteria, airborne yeasts, and oxygen in the cellar. Keg ale lasts a little longer, up to five days. Every time a pint of beer is drawn at the tap, a pint of air is drawn into the cask. One of the ways in which to solve the problem is to order the beer in smaller casks or kegs. If it is not sold in time, the rest either goes to waste, or your pub's reputation does.

Cellar cleanliness is important too. The dirtier the air in the cellar, the faster the beer will go off. Cellars should be cleaned at least once a week with a sanitiser or a pressure washer. Nor should you store food in the cellar. A bag of onions, for example, can taint the air around it, as can strong cheese in a fridge affect other food.

Beer line cleaning is another critical requirement. Beer lines should be cleaned every week, and the cleaning solutions and timing should be followed to the manufacturer's instructions. Cleaner should not be left in the pipes for longer than the instructions state, because this can deteriorate the inside of the line. Furthermore, beer nozzles also need to be cleaned. Many people soak them in water, or soda water, overnight, but they should be rinsed in hot water with a little sanitiser and washed with a bottle brush before putting them back on.