Rail maintenance sheds – too cold for comfort?

Heating rail maintenance sheds effectively and economically is a challenge many train companies are now facing with confidence. Nick Winton of AmbiRad Ltd explains.

Economy and effectiveness are the two key criteria specifiers are required to answer when selecting a heating system for rail maintenance sheds. Finding a solution to both in a single heating system can be challenging.

Rail shed design has changed little over the years. They are typically 200 to 300 metres long and around 15-20 metres wide depending on the number of tracks running through the building. To accommodate train carriages, the roof height is often 7 to 8 metres.

Entrance and exit doors often occupy the full width of the building, and may be left open for many hours a day. When doors are open at both ends, a wind tunnel effect is created, and cold air at high velocity is drawn through the shed. In some areas of the country, the problem of keeping the shed warm enough for personnel to work comfortably is compounded by the north-south alignment of the tracks which allows very little sunshine in to warm the interior.

With a constant flow-through of external air, the rail shed environment is too hostile for some forms of heating. Warm air heating, for example, would not be an appropriate solution. The system would consume fuel attempting to heat the entire volume of air in the shed, only for it to be replaced instantly with colder externally air when the doors are open to allow trains to manoeuvre in and out.

Blanket heat coverage is not generally a prerequisite. The ideal heating system – one which answers the prime requirements for economy and effectiveness – will heat only those areas where personnel are working. And in such long buildings, it should also be capable of being zoned to heat smaller working areas when necessary.

Radiant tube heating answers all these needs. It is one of the most energy efficient forms of space heating available; it burns fuel (natural gas or LPG) at the point of use so there is no loss of temperature in distributing heat around the building. Most importantly in the case of rail maintenance sheds, the warmth from the radiant system felt by personnel is less affected by cold air influx through open doors.

Radiant systems work like the sun, emitting infra red rays that warm only people and objects in their path. They do not heat the volume of air in the building, so no fuel is consumed wastefully and people remain warm regardless of fluctuating air temperatures when doors are open and closed.

Positioned directly above the working areas (ie. between trains being serviced), the radiant tubes focus all their heat exactly where it is needed – at the lowest two metres of the building. Personnel feel comfortably warm at all times, while the intense chill is taken off machinery, preventing the build-up of potentially hazardous condensation.

When operatives are working on one part of a train, zoning enables all other parts of the system to be switched off. Over time, this produces considerable fuel economies and cost reductions.

Gary Thompson of C Spencer, a main contractor on many rail shed heating projects, believes: “Radiant is one of the best schemes for handling rail shed heating. It is inordinately expensive to heat the sheds otherwise. Economy and energy efficiency are a big part of the equation.”

He cites Neville Hill Train Repair Sheds in Leeds as a good example. Here, the doors at both ends of the shed are permanently open during working hours. The existing high temperature hot water radiant strip system, powered by a central boiler, was decentralised in 2003, to be replaced by Nor-Ray-Vac continuous radiant tube heating systems from AmbiRad in two of the sheds.

In shed one, a 2520m2 building with 6metre average roof height, two tracks are accommodated. Thirty-six Nor-Ray-Vac burners were installed, divided into four zones for optimum flexibility and economy. In the second shed, of 2300m2, 30 burners, divided into four zones along the length of the building, were also installed, suspended at 5metres from floor level.

Continuous radiant tube heating offers further advantages over linear radiant tubes. The number of burners may be reduced and roof or wall penetrations can be kept to a minimum. The system provides low intensity, even heat coverage over very large areas, and is economical, energy efficient and quiet to operate. It can be easily zoned to answer local heating requirements.

A similar decentralisation project was carried out at Hornsey Rail Repair Shed. Here, six rail tracks run into the 33m wide building. A Nor-Ray-Vac system was installed to provide heating between each track and between track and walls. In total 56 burners, each with a 35kW heat output, were installed in 14 zones.

In Belfast, at the 5-track Translink Rail Cleaning Facility, the heating needs were slightly different. Blanket coverage was required to ensure operatives remain comfortably warm at all times. A Nor-Ray-Vac system with three branches across the width of the shed was installed, suspended at 7.5metres. This gives the required blanket heat coverage, both economically and efficiently, without the unique zoning, as utilised in train maintenance sheds.

Whatever the size or type of rail shed, radiant tube heating is an energy efficient solution. In these days of rising fuel costs and restrictions on ‘greenhouse gas’ emissions, reducing the fuel burden makes good sense. In the case of radiant heating, the economies and environmental considerations can be achieved without compromising the comfort or safety of personnel.

In addition, the Nor-Ray-Vac system is eligible for the Enhanced Capital Allowance (ECA) scheme, an upfront tax relief enabling the Rail company investing in energy saving equipment to claim 100% of the capital and installation costs as capital allowances against taxable profits in the first year.

Web: www.ambirad.co.uk