A good system will maintain the keg/cask cellar at a temperature between 11 and 14C. The system is split into two halves, having an evaporator and fan/s to circulate cool air cool air around the cellar, and a condensing unit which accepts the heat from the cellar, and passes it to the outside.
Beer in the cellar is best stored cooled. In cask beer, this slows the growth of yeast, preventing over-conditioning and surging at the pump. Keg beer blanket pressures are set to the CO2 content of the beer, and this changes with temperature. A constant temperature means absorption or loss is kept at a minimum throughout the emptying of the keg, so preventing gassy or flat pour. Because the evaporator is the coldest place in the cellar, with the air constantly passing through it, any moisture will condense on the fins and will be drained away. This gives a drier cellar, preventing mould on walls and ceilings.
I’m often asked how much will the system cost to run. Whilst there are industry figures to calculate this, it really is in the hands of the user as to how much energy the system uses. A cellar cooler is a heat pump. It’s job is to remove heat from a space until the preset temperature is reached. At this point most of the system shuts down, leaving a 60 to 150W fan running to keep the air circulating. So, the equivalent of up to a couple of light bulbs!
The system will stay in this condition until it senses a rise in temperature. This is usually 2 to 3C above the shut down point. If your cellar is constructed with thickly insulated walls and ceiling and your insulated door closes snugly, the system will spend most of it’s life shut down, and cost a minimal amount to run.
Sadly, in reality, the cellar is usually the place that gets the least investment, and will have little to no insulation and a badly fitting old door and holes in the walls and ceiling where services pass through. It is not unknown to see hot water pipes pass through the cellar. So the amount of heat that can ingress into the cellar will determine how much your cellar cooler really cost to run.
To save money, insulate, remove heat sources such as ice makers, beer coolers and post mix machines which should be outside the cooled space, and fix that door. Whilst the system is running, its busily compressing the cellar heat into the considerably smaller space of the condenser. This is the finned area on the outside unit. The fins are heat sinks for the copper coils inside, and a fan will blow air through this matrix, picking up this heat and discarding it. If this becomes blocked by dust and fluff, then the condenser cannot do an efficient job, and the system will have to work harder and longer to get the cellar down to temperature.
As a rule of thumb, the efficiency drop in percentage to the amount blockage of the airflow through the condenser, so lightly soiled, 10 – 30%, if you have a really furry condenser up to 70% drop in efficiency and if very bad it will either shut down because of excessive heat and high pressure or worse still, the compressor will burn out! Switch the system off and gently brush the condenser in the direction of the fins removing any fluff, seeds and dust. Do this once a month, and remember to switch it back on when you have finished. Don’t worry if it doesn’t start straight away, the system’s often use a anti-frequent start timer of up to 5 mins before starting.
Finally, have the system serviced at least once a year. Your refrigeration engineer can effect a deep clean on both the condenser and evaporator coil. He will clean the condensate tray, check the refrigerant level, and give you an evaluation of your system as to corrosion and other problem he may foresee for the future life of the system.
If you are looking for a new system, then can I offer the following advice.First find a qualified refrigeration engineer. These can be found for your area by referring to the REFCOM website, which keeps a list of all FGas certified engineers. http://www.refcom.org.uk/
The refrigeration engineer will measure your room and note the heat ingress and size a system for you. Don’t ask for the cheapest system! Whilst they will all do the job, but a cheap systems efficiency will drop quickly and will not last as long. Some systems qualify for an ECA under the government’s carbon trust scheme, a good indication of a system that will last a long time whilst using less energy to run. Finally, most engineers will advise on the cellar’s insulation properties. This is not to give his builder mate a job, but to help you get the very best out of your system.
So cellar cooling – why bother. Well, if you want to store and present your beer in tiptop condition, increasing sales and reputation, then cellar cooling is a must.
Jes Shotter works out of Hailsham trading as JS Refrigeration servicing refrigeration equipment also installing cellar cooling for Carlsberg, Scottish & Newcastle and Heineken Breweries and are the main refrigeration contractors for Harvey’s Brewery.