Mechanical and electrical (Maybush)

Boiler House, facing NE towards pump area

This page details the mechanical and electrical (M&E) infrastructure at Ordnance Survey’s former head office in Maybush (Southampton).

Where individual plant rooms have their own page then they are described there but hyperlinked – REWRITE THIS

This page contains general information on the mechanical and electrical systems that kept the Maybush head office running and provided essential services. This subject may be of little interest to the average reader, however I hope that somebody finds it interesting to know how our old head office building ‘worked’. I will assume little prior knowledge of building services and try to explain things in simple terms.

Heating

Most of the WRB is heated by a combination of warm air and hot water heating technologies. Under every window in the standard offices is an induction heater unit – hot water from the boilers is pumped around the building to these units where it enters a heat exchanger (consisting of lots of thin metal fins, much like a car radiator). Air is circulated from air handling units in the penthouses on the roof through ducts and then enters the offices after passing through the heat exchangers – the relatively high surface area of these heat exchangers is designed to transfer the heat from the water to the air.

Areas that, for whatever reason, did not have access to air from the ventilation system were heated by radiators, although there were actually very few such areas. The Print Floor and Business Centre, and some other areas that were air-conditioned were heated in other ways; these are explained elsewhere within this article.

The hot water for heating originated from the Boiler House, located adjacent to F core. Originally, three oil-fired boilers (two large and one small) produced this heat. The fuel oil was stored in underground tanks beneath the boiler house. The steps leading down by F door led to the door to the tank room – this contained the pumps and inspection hatches for the underground tanks. These have not been used since the mid-1980s but are still in situ. The building was constructed during the height of the Cold War and it was said that the tanks could store a month’s supply of oil! The tanks are certainly far more extensive than would normally be expected of a site this size. According to a hand-written note on the back of an old photograph, the boilers would use 75 000 gallons of oil a month at peak times and could output 20 million BTU of heat (5 857 kWh!)

Boiler House - original equipment
Boiler House – original equipment

In the mid 1980s, the original boilers were replaced with five new gas-fired boilers. This must have been a major operation as the layout of the boiler house was drastically changed at this time, the new boilers being in a different location and orientation to the original ones. In 2000, three of these boilers were removed to make way for a new combined heat and power (CHP) system. Two of the boilers remained until the building was demolished to make up the demand for heat during the coldest weather.

The CHP system consisted of two Jenbacher gas engines – these are just like an electricity generator that is powered by gas. Those at Maybush generated electricity at 11 KV, which was routed to the substation and helped to meet part of the site electrical load. Like any type of internal combustion engine, heat is produced as a by-product of the CHP system and this heat goes through a heat exchanger that transfers as much heat to the heating circuit as possible, helping to reduce the load on the boilers, or during the less cold months, eliminating the need for the boilers to run at all.

One of two Jenbacher CHP engines - note the huge spark plugs!
One of two Jenbacher CHP engines

The main drawback of the CHP system was that the heat needed to be ‘disposed of’ – if there is no need for it in the heating circuit, then it still needed to be disposed of. Typically, it was ‘dumped’ into the site’s main cooling system – this had to dispose of all the unwanted heat from production areas and the IT suite and adding the heat from the CHP meant the cooling system had to work harder – this at best wasted electricity (thus mitigating the electrical-generating benefits of the CHP) and at worst overloaded the cooling system, so the CHP was often shut down during the warmer months, when there was no need for the heat it produced. The CHP engines and their associated equipment (control panels, lubrication oil tanks, and transformers) were removed before the building was demolished – as they were fairly new then they were presumably sold, as all the other M&E equipment, including the boilers, chillers and cooling towers, was destroyed by the demolition contractors.

Simplified diagram of a typical heating system with CHP
A typical heating system with CHP

Services Block had overhead unit heaters dating back to the 1960s, believed to be ‘Copperad’ brand. Believe it or not, these exact same heaters are still on the market today! They take hot water from the heating circuit and blow air over a heat exchanger, directing it downwards into the workshops. The control panels for these heaters look ancient but were largely still in place (although largely non-functional) until that building’s demolition.

Unit heater controls in the Bilby Store
Unit heater controls in the Bilby Store

Water

The Maybush site has two distinct and separate water circuits. The drinking water taps located in kitchenettes and lavatories are served directly from the mains so the water from them is exactly the same as the water local householders would get out of their taps.

The other taps are labelled ‘NOT drinking water’ because this water may have been stored and processed. Anyone who lives in a hard water area will realise that limescale impairs the efficiency of appliances and that is exactly the same here. A lot of machinery, such as humidifiers, boilers and some production equipment used water and if hard water straight out of the tap was used, the equipment would soon fur up. The process water was ‘demineralised’, typically using salt and some of it (depending on the application) is treated using further chemicals so that it is resistant to Legionnaire’s disease. This is not an issue for the drinking water as Legionella only breed where there is warm standing water, for example, cooling towers or hot water systems – hence why this water has to be treated.

Boiler House water treatment plant
Boiler House water treatment plant

This non-drinking water is pumped to the top of each service core, where it is stored in very large metal tanks in the penthouses. Using exactly the same principle as the water tank in the loft of a house, the taps, toilet cisterns and so on are fed by gravity from these header tank. The water tanks installed are ‘sectional’; these are assembled on site using prefabricated modular panels. The water-storage capacity of these tanks was considerable and it was a common sight to see fire engines filling up from the huge cold water storage tanks on the rooftop penthouse of F core.

F core penthouse - CWS tank
F core penthouse – CWS tank

Drainage and sanitation

Not a nice subject but one that is concerned with the building nonetheless, drainage and wastewater disposal is vital to any building. There are two drainage systems at OS HQ – surface water drains and ‘foul’ drains.

Surface water drains collected run-off water from rooftops, car parks and other made surfaces and as the content of the drain was nearly all water, it could be discharged straight to a river or other watercourse without being treated.

‘Foul’ drains served process water, sinks and lavatories, as well as the Restaurant, which had a waste disposal system that shredded semi-solid food waste and discharged it to the drain. Each service core has a drainage stack and the water went through an oil interceptor (located behind Services Block) prior to leaving the site. This was intended to trap any oil that may have been in the water – when Services Block was used for servicing cars, this was probably quite likely to happen although modern processes used less chemicals and stringent controls were in place to mitigate the risks of spillage – special ‘spill kits were located in all areas where hazardous materials such as chemicals or oils were stored and handled and staff had been trained in their usage. The contents of the foul drains must go to a water treatment works (probably the sewage works in the docks) before the water recovered could be discharged to a watercourse.

Lavatories were located at all of the service cores; most cores had both male and female lavatories, although some, such as B core on the first floor and G core on the LG floor, only have one type. As well as the standard open-plan lavatories with cubicles, some of the vestibules by A, B and C cores had what used to be called ‘executive toilets’. These had a single WC and washbasin. Apparently, these were locked and senior staff had a key for them, although in more recent years, all staff could use them. All the toilets on site (except in Services Block, where there were some original toilets; much more spartan than the refurbished ones) were completely refurbished in the mid-late 90s.

There were additional toilets in the new Reception area and in the Restaurant’s rear lobby. There used to be extra lavatories in the front lobby of the Restaurant but these were removed at some stage; they must have been small. Services Block also had some toilets.

The flat roofs of the building have small holes in for water to drain away; the water drains through a tube inside one of the pillars. However, this has never worked very well, with standing water causing leaking roofs for many years.

Hot water

Most of the ‘domestic hot water’ (DHW) at OSO Maybush (that is, anything apart from the hot water used for heating), such as that for hand-washing, kitchenettes and so on, was heated in a similar way to such hot water in domestic homes. The primary heating circuit (from the boilers/CHP) went through a coiled pipe in a tank of water to transfer the heat. The reason the primary heating circuit water is not used is a) it is generally too hot for domestic use and b) it is less suitable for ‘domestic’ use, having been treated and circulating in the system.

The hot water tanks on the site were generally referred to as ‘calorifiers’; and some were so large that they were mounted horizontally rather than vertically, otherwise they would be too tall for the plant room! The calorifiers were located in the back of the boiler house, the plant room containing the sprinkler pumps opposite B lift at LG floor level, the plant room off the LG corridor between B and C cores and in the plant room beneath the Restaurant.

Cooling

The site had a dedicated Refrigeration Plant room containing three chillers. Originally, the chillers were supplied by Carlyle but that company has now been taken over by York. One of the original chillers remains in use but the other two have been replaced with larger and newer York chillers. The chillers were supplied with electricity at 3.3 kV.

York chiller in the Refrigeration Plant
One of the York chillers

A chiller basically works the same way as the compressor in the back of a domestic fridge. There is a circuit, much like the heating circuit, of chilled water that is circulated around the site and used by various processes that require cooling, much like the pipes inside a domestic fridge. The chillers transfer the heat from this circuit to a second circuit, the heat rejection circuit (known as ‘condensate’). This works in a similar way to the grille on the back of a domestic fridge.

There are several ways of disposing of waste heat, probably the most common is the air-cooled system, which again works like a fridge only with a fan to help the circulation of air over the coils but the primary system at OSO Maybush was an evaporative cooling system known as cooling towers. The phrase ‘cooling towers’ probably evokes images of huge concrete towers next to a power station but the type of cooling tower here uses the same principal, of using evaporation to cool the water. The name ‘cooling tower’ is perhaps slightly misleading as the ones at OSO Maybush were are not really ‘towers’ as such but they worked the same way as those concrete ones in power stations, except that those at Maybush used a fan to circulate the air rather than a ‘forced draught’ of natural air. Evaporative cooling is also used by the body, through sweating, to cool down.

The water in the heat rejection circuit was pumped to top of the cooling towers and sprayed over a fan, the water that left the towers was cooler than when it entered. Some water evaporated to the air during this process so a supply of fresh water was added to keep the system topped up before it returned to the chillers to begin the cycle again. The cooling towers were mounted on the roof (7th floor) above K core, adjacent to F Core Penthouse

Visco cooling tower no. 1 fan
Visco cooling tower no. 1 fan

Poorly-maintained cooling towers are known to be one of the main causes of Legionnaire’s disease, however Ordnance Survey had a stringent regime to ensure that this did not happen. The water fed into the cooling towers was treated with chemicals that prevented bacteria from breeding but the cooling towers were also monitored regularly.

The chilled water was pumped around the building to heat exchangers used in various air conditioning equipment – see Ventilation for details.

Simplified diagram of how cooling systems work
Simplified diagram of a typical cooling circuit and water chiller.

Ventilation

There are two primary types of ventilation – natural and mechanical. Natural ventilation is the simple act of opening a window while mechanical ventilation is anything from a simple desk fan to a complex centralised ventilation system.

The WRB office spurs have air handling units (AHUs) in the rooftop penthouses above E, F and H core. They suck in air from outside and it is passed through filters made of pleated cloth and then through heat exchanger batteries (that preheat the air). Huge centrifugal fans then distribute it through a network of ducts. These go down though the riser cupboards located next to the lifts and on each floor, smaller ducts branch off to vents located above the doors from the main offices to the lift lobbies. These ducts, attached to the ceilings, were concealed behind the metal false ceilings to the lift lobbies. Separate air ducts serve the unit heaters underneath the windows as already mentioned.

Lavatories have an extractor fan system that again, is located in all the penthouses.

Toilet extractor fans, E core Penthouse

Production areas

The industrial areas of the WRB – not just the factory floor areas beneath the vaulted roof but pretty much all of the ground and 1st floor of the WRB – were used for a variety of different reprographic purposes – printing, exposing plates to light, coating plates in various chemicals, photographing maps, photographic developing, letterpress printing and diazo (a particularly noxious method of duplicating) to name but a few. Not only was it important to remove the fumes but printing and paper storage in particular needed a very specific indoor climate so there was a massive ventilation plant, which occupied the entire 2nd and 3rd floor of the central spur (B-K core) of the WRB.

There was a very complex network of ventilation ducts connecting these areas to the main ventilation plant. Each side of the central spur (that is, the Print Floor on one side and Helio & Photographic on the other), had its own ventilation system and these, as far as I know, were completely separate. There were five individual ‘plants’ on each side. These were separate but air from them would have mixed in the work areas they served. Each plant was identified with a letter; from K core to B core; they were designated A, B, C, D and E on the Helio side and F, G, H, J and K on the Print side. Note the convention of avoiding the letter ‘I’ that was also used when designating the lifts/cores. Plants A, B, C, and D were identical and F, G, H and I were too. The plants at the B core end (plants E and K; hope you’re not getting too confused with all these letters!) were largely the same as the others on their side but the ducts they output to were very different.

Fan 'K', 3rd floor vent plant
Fan ‘K’ in the 3rd floor Print Floor ventilation plant

Each plant, except the two at the B core end, served two of the eight vaulted roofs on each side. Plants E and K served the front part of the production areas, that is, A-B-C core. Details of these ducts will be discussed later. We’ll now into detail about the ventilation plants, or Air Handling Units (AHUs) in the central spur themselves. AHUs are commonly used in large buildings for ventilation and air conditioning but they’re usually separate packaged units. The AHUs at Romsey Road were built-in as part of the structure and were large enough to stand in. Although it was very noisy in there, I never particularly noticed a breeze of any kind.

On the Print Floor side, each plant, which took up three bays, took in air from outside, mixed it with recirculated air, filtered it, cooled and heated it if necessary and humidified it as well. A large axial inlet fan mounted to the floor slab drew in air from the 2nd floor below and passed it through two filters – a pleated filter made of paper-like material and a bag filter. These trapped any airbourne particulates that may have been present. The air then went through a cooler battery; basically a large finned heat exchanger that contained chilled water; the intention being to cool the air as necessary. A large centrifugal output fan blew the cleaned air down through the floor into the ducts on the second floor below. A makeup duct entered the AHU just before this fan. Usually about 90% of the air was recirculated through the AHU while 10% of fresh air was added. There was a damper to regulate the amount of fresh air.

The fresh air to the makeup duct was brought in from outside via louvred vents in the windows and the air went through a ‘Fresh Air Plant’ (FAP). The FAP was a much smaller AHU that was mounted within the large AHU chamber; this was mounted on a metal frame above the aforementioned intake fan. The FAP included a pleated filter, heater battery, humidifier, cooler battery ad a centrifugal fan to the makeup duct. The Spinning Disc Humidifier sprayed water over a rotating disc that vapourised the water droplets.

Print Floor ventilation plant - Fresh Air Plant and extract fan
Fresh Air Plant and extract fan. This is a smaller AHU inside the main AHU!

The Helio side initially only had a heater battery in its AHUs but FAPs were retrofitted not long after; presumably, the ventilation only system was inadequate for production activities.

On both sides of the second floor below, air was routed from the AHUs to various parts of the building. A chamber below the AHUs’ output fan led to horizontal ducts that twisted to a 45 degree angle (so that it fitted in the vaulted roofs). A further cooler battery was in the duct to further cool the air if necessary. On the Print Floor side, the roof ducts ran right to the end of the vaulted roof, with outlets at regular intervals hidden by the suspended ceiling. On the Helio side, the roof ducts went to the end of the vaulted roof and then beyond, into the Photographic Section. That area was single-height on the ground floor with suspended ceilings and these hid the ventilation ducts and the full-height 1st floor void above. The ducts got narrower the further they went from the AHU plant; otherwise moving air all that way would have needed a lot more pressure to get it all that way, particularly as little attempt seems to have been made of ‘streamlining’ the ducts; there are numerous 90 degree angle bends, including directly below the AHUs’ output fan. Plants A and F have a slightly different arrangement; as they are not adjacent to the vaulted roofs they serve then their output ducts come out from the central spur and turn towards the back of the building until they are adjacent to the roof ducts they serve. This duct is concealed by suspended ceilings on both sides.

Air was returned to the plants via grilles in the second floor wall adjacent to the factory floors. There was one large chamber with all the grilles and the supply ducts that bypassed this chamber. The chamber on each side was bricked up from the ‘Maintenance Corridor’ in the middle and there were several doors, with air-locks that provided access. The AHU intakes drew the returned air from the chambers.

The ‘Maintenance Corridor’, its official name on building plans for some years, could be viewed by anyone on the second floor of K stairwell as it had windows in the doors. Its enticing complexity served the rest of the ventilation plants, with it housing pumps, valves for isolating sections of pipework, electrical controls and pipes providing fresh water for the humidifiers, heated water and chilled water.

The front (by B core) plant on each side was very different (or at least the ducts they were connected to were; the plants themselves look much of a muchness to me). Plant E and Plant K served the ground and 1st floor front work areas. The bay of B core that is adjacent to the ventilation plant has a lowered 2nd floor that allowed the ducts from the 2nd floor to enter the top of the 1st floor and split into dozens of branches; the smaller ones appear to have served the front work areas (C150/C128) but the largest branches were two vertical ducts, one for each side, that went through the first floor to the ground floor. I always assumed that these branched off into the ceiling of the ground floor at the front but it appears not to be the case. The vertical ducts did another turn, went through the ground floor and then another 90 degree turn took it to a duct that ran parallel with the Subway. This went from B core and all the way along the front until C core, just below the floor level. Holes in the floor, I assume, got this air into the work area albeit via a very convoluted route. Another duct, a mirror image of the Print Floor one, existed on the other side for the Helio/Photo area. I’m not sure how long that duct was used for. Mid-late 90s is probably when it was shut down. I can imagine running that massive air-con plant was an ecological disaster; there were at least eight 90 degree turns between the air-con plant and the duct I am writing about. While green issues were not considered as important as they are now, that would have cost a great amount in electricity.

When the first floor was refurbished in the mid 90s, it was pretty much completely stripped out and all those ceiling ducts went with it; the mechanical ventilation not being needed when it was changed from photographic labs to office space. The two large vertical ducts at B core to the floor below appear to have been left in-situ, as they are shown on the various floor plans around the building (adjacent to the C131 Trade Union Side office). They were approximately 2 metres square. On the ground floor below, there were two chambers directly below but twice as wide that connected the duct above to the one below, the extra width accommodating a double turn with respect to the fact that the ducts above were further back. That setup appears to be completely gone, presumably when those areas were also changed from Repro to office space. This means that the underfloor duct has been amputated from the air-con system and has therefore been ‘mothballed’, unless it was put to use as a good place to hide cables in the new offices. In the second floor plant room, the original ducts from the plants above to B core also appear to have been removed, which begs the question of what the plants were used for after that. One answer I don’t have.

When the Graphic Repro area was vacated in the mid-late 1990s, its ventilation plant was removed in its entirety. Most of the brick walls that made up the third floor AHUs were removed and a lot of the walls below were as well. The Business Centre project required a very different ventilation system and new ducts were installed on the second floor. Much smaller packaged AHUs were installed on the third floor above.

For some images, please see Centre spur plant room – 3rd floor and Centre spur plant room – 2nd floor

West Block does not appear to have the same standard of mechanical ventilation as the rest of the building although some areas were air-conditioned.

Originally, only the computer suite in W404 was air-conditioned, using a large plant room adjacent to it and ducts in the ceiling. This became less important when that computer room was decommissioned and the area converted to offices. The ‘new’ (then) computer room in W407 was converted from a space originally used for map storage. A large metal ‘shed’ was erected on the roof of West Block, adjacent to F core on the 6th floor. This contained one large ‘Biddle’ AHU, with filters, cooling and humidity. Air was sucked in from outside and distributed through massive ducts that straddle the original northlight glazed roofing.

Due to the impact that a failure of this plant would have on computer operations, it was replaced by separate small AHUs (approximately the size of two network cabinets) in the computer room itself. These were entirely separate from the site’s main chilled water and refrigeration system and their heat was dispersed via small air-cooled condenser units on the roof adjacent to the roof of W407. The original system remained in a decommissioned state until the buildings were demolished.

Original air handling unit for W407
Original air handling unit for W407

Also on the 4th floor of West Block was the air-conditioned W416 office, used by HR until the mid 2000s. Chilled water pipes for this area ran on the top of the roof and entered the F core penthouse through one of the windows. The same applied to W212 below it. I am not sure how the ventilation system for that worked, there must have been an AHU hidden above the suspended ceiling.

The Restaurant has its own ventilation system, a small-scale system for the flat roofed area facing Romsey Road and a full-scale vent hood extract system over the kitchens. Ever wondered what all those sheds on the roof are? Well they house the fans for extracting the fumes from the kitchens and also the Restaurant’s flat roofed areas. These systems have to be well maintained and the filters changed regularly, otherwise the smoke and fumes would find their way into the public areas. Blocked filters may also pose a fire risk.

Simplified diagram of how an Air Handling Unit (AHU) works
How an AHU works

Electricity

The site was originally served by one three-phase 11 KV electrical feed, which went to the three transformers located adjacent to the substation building.

In 2004, Compass House gained its own, separate electrical supply when a small, separate substation and distribution equipment was constructed underneath the colonnade. This was done because the low voltage distribution board (LVDB) in the main substation serving the whole site was obsolete (dating from the time of construction). The main LVDB had to be replaced and rather than allowing provision for Compass House on the new unit, providing an independent supply for Compass House would minimise disruption to the tenants and was also thinking ahead to when the main buildings would be demolished, otherwise leaving Compass House without an electricity supply.

New (as of 2004) main electrical switchboard

Going back now to the main substation for the Ordnance Survey buildings, electricity is stepped down to 230 V and fed to smaller distribution boards around the building, usually located in the riser cupboards (that’s what is behind those doors next to the lifts). These distribution boards are like a larger version of a domestic fusebox, allowing different rooms to be isolated from the mains when work needs to be carried out. There are distribution boards at E, H, B, K, F and G cores.

The Print Floor and Helio sections, as well as their lighting and air conditioning plants, had their own electricity supply, distributed from the switch room adjacent to K core stairs on the ground floor.

Three-phase electricity at 440/415 V is also used by some of the plant equipment around the site, such as pumps, motors and process equipment.

The original 1960s plant equipment was controlled by the same type of control panel. These had an innovative design in that the modules could be withdrawn from the cabinet like a drawer and replaced with another module; this greatly reduced the need to turn off the power to other equipment. These were all finished in a lemon colour and were manufactured by Scottish electrical equipment manufacturer Belmos Peebles.

F core penthouse motor control panel
F core penthouse motor control panel

Mains electricity to the site is sourced from a ‘green’ energy tariff but Ordnance Survey has gone above and beyond the call of duty with its commitment to sustainable energy. In 2000, a combined heat and power (CHP) system was installed on site (see the chapter on heating for more information); this generates electricity that is fed to the substation and supplements the mains supply – as of 2010, the CHP supplied around half the site’s electrical load. The gas burned by the CHP therefore produces both heat and electricity, reducing our fuel bills and saving us money, as well as making us exempt from having to pay the ‘Climate Change Levy’.

Contrary to popular belief, generating most of the site’s electricity on site did not protect it from power cuts – the CHP relied on electricity to operate and the connection to the substation was not configured to switch between mains and CHP power in the event of the mains supply failing. The system could be set up so it was capable of providing power during a power cut but this would require spending money and the option was never taken up.

There are two small generators in the refrigeration plant room but their purpose is unknown. A few years ago, action was taken to remedy the unacceptable situation of vital IT systems having to be shut down on a regular basis due to electrical works and power cuts. A large standalone generator (which looks like a green shipping container) was installed adjacent to the substation, along with an adjacent separate diesel fuel storage tank. This can meet the site load for essential services during a power cut or planned outage. There is also a new UPS room on the roof of West Block with numerous batteries to ensure that business is not interrupted. Backup power batteries were installed on the roof of West Block at around the same time.

Lifts

See the separate page on Lifts.

Pulse clocks

When the building opened, it had a system of synchronised electric pulse clocks. Such systems were once popular but are rare nowadays due to the fact that cheap battery-operated standalone clocks have become available since the 1960s.

At the heart of the clock system was a ‘master’ clock, this generated an electrical pulse once a second. These pulses were fed through cables around the building to wall clocks in offices and other areas and each pulse moved the clock mechanism by one second. This had the advantage that everyone was working to the same time.

It is not known when the pulse clock system was discontinued but only a few of the wall clocks remain, usually in areas off the beaten track, of no use now without the pulses sent from the ‘master’ clock. The ‘master’ clock was located in the old main entrance hall (North Block ‘D’ core) and was presumably disposed of when North Block was refurbished.

Master Clock and fire alarm panel
Master Clock and fire alarm panel

There is a contemporary equivalent of the pulse clock system – the clocks on our PCs are synchronised by a server.

Asbestos

One of the main problems with the William Roy Building and the other 1960s buildings on the site is that asbestos was used in their construction. The majority of this was used for stopping the spread of fire or smoke between floors. In the riser cupboards, and those behind the lavatories, various pipes and ducts go between the floors and the holes in the floor slab for these need to be sealed up, typically with asbestos.

Asbestos was also used for a few other things on site – lift motor brake pads, old toilet cisterns (more of an issue in Crabwood House than the main buildings), sealing up electric switch boxes. Most of it was encapsulated with more modern materials or removed by specialist contractors but it was found in the ceiling of the Staff Restaurant when it was refurbished in 2000-01 and meant that it was closed for a long time while it was removed.

All the remaining asbestos had to be removed by specialist demolition contractors in 2011-12 before the building itself could be demolished.

Glossary

There is a lot of jargon involved in mechanical and electrical systems so I will attempt to explain some of the terms you may see used in photographs on this site.

  • AHU = Air Handling Unit. A device that takes in air and filters it, as well as changing the temperature and sometimes humidity.
  • Condenser = The part of a refrigeration system that discharges unwanted heat.
  • Condensate = The water that is used to cool a chiller.
  • Evaporator = The part of a refrigeration system that absorbs unwanted heat.
  • FAP – fresh air plant – a type of AHU that introduced fresh air from outside
  • Chilled water = Water from a chiller that is used to cool down parts of the building
  • Flow (or feed) = Heated or chilled water supplied from a boiler or chiller to radiators or air handling units.
  • Return = pipe that returns water from radiators or heat exchangers to the boiler or chiller.
  • CWS = Cold Water Storage
  • LTHW = Low temperature hot water – this may sound like an oxymoron but is used in comparison to high temperature hot water, which typically is above 80C.
  • DHW = Domestic hot water. Basically, water that is used for anything other than industrial processes or central heating, for example, water in kitchens/lavatories.
  • Riser = part of a building where pipes travel vertically between floors.
  • Core = part of a building where services are grouped together, for example, risers, lifts, lavatories, kitchenettes and so on.
  • LVDB = low voltage distribution board, a board containing switches that can isolate parts of the building from the electrical supply.
  • Busbar = A set of metal bars that distribute electricity from the LVDB to distribution boards.
  • Calorifier = a posh name for a tank where water is heated indirectly (that is, from a heating coil).

Source

Article written by Gary Tull; please note that this article is written from my knowledge and may, therefore, be inaccurate (so would never go on Wikipedia) but the general principles should be there!

Updated 6 Dec 2019, moved to WordPress and images reimported, still needs updating to past tense – GT
Originally created on the now-defunct OurWiki on 14 July 2010 – GT

Last updated on Wednesday 17 February 2021 by GaryReggae