THOUGHT PIECE the carling team

In The Beer Cellar – The Engine Room Of The British Pub

What makes a good pub? Is it good food or a cosy open fire in winter or a pub garden in summer or even clean toilets? Is it mine host or the choice of drinks behind the bar. Does it come down to space to park the car or the proximity of a bus stop so you can have more than one or two?

The British pub has been a key part of the local community for centuries and is much envied outside of these shores. Since ancient times pubs have served as social hubs where people gather and talk to friends and neighbours. The recent closure of these facilities must have contributed to a general feeling of loneliness during lockdowns. A study by the Medical Research Council found that men drinking with friends in the pub reported positive effects on their mental well-being so it’s good to talk and it’s even better to do so over a pint. A coffee bar is not a pub but it is a social hub so the key to the pub must be its beer and the key to good beer must be a good cellar.

Despite what the Americans may think, our forefathers did not want beer to be too warm so the cellar would be situated below the bar. This would be cooler and saved on ground floor space. All beer would be in wooden casks and there would be a raised plinth along each wall upon which to ‘stillage’ or set the casks on their bellies. To save even more space, the steps would be steep as if all cellars were designed by shipwrights! The potman would hazard these steps many times an hour fetching jugs directly from the cask. Early health and safety crept in when the first patent for a bar top piston beer engine was lodged in 1785.

Barmaids developed good muscles pulling the beer from below and the beer lines had to be 5/8” id (16mm) and the length of run minimised otherwise the job would have been impossible. Each three metres of pipe contained a pint. Pipes needed cleaning as biofilms built up and wastage was considerable. Landlords would have been tempted to collect residues, filter them and add them back to the cask, it was this widespread and poorly conducted practice which probably led to the formation of CAMRA in the first place!

Keg beers (brewery conditioned, filtered, carbonated and pasteurised) appeared widely in the 1950s using gas pressure to drive the beer upwards to the dispense taps. Again pipes were large diameter to avoid having to use high carbon dioxide pressures which would increase the gas content in the container and the resulting froth gave more temptation to add back into the mild!

Consumers became more temperature and foam conscious and the cask beer engine cylinder reduced from a half to a quarter pint. This was easier to insulate and chill with a water jacket between serves. A swans neck introduced beer at the bottom of the glass and an orifice plate in the device allowed controlled foaming so that a perfect pint was presented to the customer.

A typical keg cellar installation and a cellar reporting board

This brief history lesson shows the importance of correct temperature, correct head on the beer, reduction of wastage and attention to cleanliness. It allows us to introduce the modern beer cellar which is more often than not situated at the ground floor level.

The Beer Tech cellar monitor which will import cold air from outside to save energy

It is for beer only and must not be used as a useful larder extension, there should be no evidence of pets and no motorbikes. It should be tidy, well lit and the floor should be washable without puddling. It must not smell musty from the drain. There should be a cellar board to record beers on sale, best before dates, records of line cleaning, glass renovating, as well as glasswasher and ice machine routine cleaning. Containers must be sold in the correct order. The pub EPOS till can collect all sorts of information sometimes including beer meters on the lines so that sales can be reconciled remotely. One further development in the chilly climes of a British winter is a device by Beer Tech which monitors the temperature inside and outside the cellar and controls the internal conditions by drawing cold air inside and thus saving electricity.

A Flojet diaphragm air pump

34.5% of the UK’s beer is sold in keg against only 6.6% in cask so we shall start with the keg. With health and safety considerations, kegs are getting smaller. The 100L (22 gallon) is probably the largest these days followed by 50L and then 30L as well as Dolium or KeyKeg one-way containers for more specialist products. Top pressure gas, either CO2 or mixed CO2/nitrogen is used to maintain the brewer’s gas content and to push the beer to a diaphragm gas pump (known as a Flojet G56) which then propels the beer to the tap. For long runs where the pressure required exceeds the SWP (safe working pressure) of the container this is essential. Ideally the Flojet is used with an air compressor but is more usually fed with gas from the cellar ring main which obviously makes it more expensive to operate and demands good ventilation if CO2 or a mixture is used. These can pump 18L a minute and became popular as an alternative to the electric induction pump that required a pressure switch to prime it and all the usual faults associated with anything electrical in a damp cellar.

A Cellar Buoy fob detector

The other vital piece of keg equipment is the fob detector or line primer (aka cellar bouy) which stops unnecessary waste at the bar when a keg empties. A float is weighted to sit just under the liquid level and as the keg empties the beer drops in the chamber along with the float. The float seals itself on an O ring thus cutting the flow of beer to the bar while the beer line to the bar remains full. The keg is then changed, the chamber flooded via a vent lever and once full of beer again the float is released and the beer will continue to pour.

Keg beer used to be carbonated only and the huge frothy heads increased drip tray wastage and in Europe encouraged the spectacle of a spatula to ceremonially scrape the head off and waste even more. Nitrogen gas entrained in beer will produce a creamy tight head of small bubbles and much pioneering work was done by Guinness to enhance the head on its stout. Ale brewers followed and added nitrogen to keg ales to yield a smoother palate more akin to a cask beer. Now it is common in lagers and allows the CO2 bloat and burp to be reduced while retaining a good head. If the brewery puts 35ppm nitrogen in, how does the cellar keep in there? CO2 cylinders hold liquid gas under pressure at cellar temperature while nitrogen is still a gas and a busy pub would need dozens of heavy cylinders a day. Far better to extract it from the air using a molecular sieve and store the nitrogen in a bank of static receivers. Then it can be blended with CO2 to produce ratios of 60:40 (always CO2 first) for fizzier lagers and 30:70 for ales and stouts.

From the left: Large carbon dioxide cylinders outside with nitrogen receivers on the left; a BOC molecular sieve to remove nitrogen from air; mixing the carbon dioxide and nitrogen; gas goes in the side of the keg coupler and beer is forced out of the top

The final keg challenge is temperature. Lagers are served at 5-6oC with extra cold versions at around 2-3oC. Bass tried a beer-slushy at -2oC called Arc in the 90s but it did not catch on. The cellar will be kept at 12oC, essential if there is cask beer and it is unwise to lower kegs further as lower temperatures will dissolve more gas which may cause fobbing later as well as being wasteful if a large space is to be cooled. Ambient storage is possible without cask but the cooling to the bar needs to be more sophisticated to cope with varying input temperatures.

The classic system to get the beer to the bar is via beer lines with coolant flow and returns in insulated tubes known as pythons (for obvious reasons). Here the lines to the bar pass through a chiller called a remote, usually with eight lines and they are then kept cold by chilled water or glycol circulating through 15mm pipes in the centre of the insulated python. The length of coil in the bath defined the desired serving temperature and the python merely kept the beer at that temperature to the tap.

A classic remote installation with eight different coils in a coolant bath. On the right is a modern R290 chiller feeding coolant to the python and on to the final under-bar trim chiller pods

Lager lines were clustered around the coolant pipes and then keg ale lines on the outside and sometimes cask ale right at the periphery where the temperature will be higher. This latter system is far from ideal as the cask beer will get overchilled during quiet trading so it is better to have a separate ale python fed with a bath of water at around 8oC that allows for some heat pick up on the beers journey through the python to maintain cellar temperature up to the tap.

To save wastage during line cleaning, many lager lines are now only ¼” (6mm) internal diameter or one pint in 18m. Further beer volume savings can ensue by using the remote only to supply cold coolant through the python and on into cold tube trim chiller pods just before each tap. The advantage is there are no beer coils in the remote chamber which increase the volume of beer lost with every clean. Sixteen beer connections as well as two for coolant to the python make any maintenance on the remote chamber very time consuming. Older coils did corrode and beer contaminate the coolant but today’s 316 stainless steel should prevent that happening. A further big advantage is that the remote need not be sited in the cellar close to the kegs which gives more flexibility in cellar design and saves beer storage space. The product is thus pre cooled by the python then cooled to correct serving temperature via the final chillers. The only disadvantage is finding a suitable place to site the Cooltube or Cold Pod (brand names from Brewfitt and Booth) under the bar, especially when retro fitting.

The Brewfitt Cooltube; the beer passes through the coils giving a huge surface to contact the coolant fed from the R290 cooler via the python

The introduction of hydrocarbon refrigerant coolers using R290 which is a highly refined propane that is a safe, environmentally friendly alternative for the hydrofluorocarbons with a zero global warming potential. Such refrigerants have resulted in greater energy efficiency, reduction in the compressor size required and quicker cooler bath temperature recovery time during busy trading.

Drinking really cold beer is rather painful so we wonder whether the younger customer today likes to buy it cold as he drinks so slowly that it has reached a pleasant 9oC at the end of the glass!

Next time we shall explore how to get the perfect pint from a cask.