Boiler house and plantroom application

Gas detection should be fitted in all new and refurbished boiler rooms where the boiler house forms part of, or is attached to, the main building, as discussed in Building Bulletin 1003 (3.1.8) and IGEM UP/11. In the event of a genuine fire alarm, both the gas and the electricity supply to the boiler house should be isolated. If an automatic proving device (that is, gas pressure proving) is fitted, then automatic restarting is allowed after an interruption to the building electricity supply. This has a particular advantage – for example, in minimising the potential of pipes freezing after a power-cut during unoccupied weekends and holidays.

IGEM/UP/1A Edition 24 requires ‘the closure of a valve, for example, the electronic isolation valve (AIV), can result in the complete loss of pressure which necessitates tightness testing and purging before resumption of supply‘. This means that if, for whatever reason, the valve closes, a gas tightness test – and, on very large installations, purging – may need to be carried out before reopening the valve. Practically, this means that, if the gas pressure has dropped to 5 mbar or less, there is a requirement to test for tightness. A gas-proving system would be able to make this test at a push of a button; the alternative is a physical test by an engineer.

Combined gas-detection and pressure-proving systems, designed specifically for use in education building boiler rooms, are available. Combustible gas and carbon monoxide detectors can be connected to such a system, so that – in the event of detecting high levels of either gas – the gas supply would be isolated. An output to a building management system or a visual indicator, such as a flashing beacon, can be mounted outside the boiler room. Otherwise, in the event of the gas being isolated, the building heating and hot-water systems will not operate – potentially resulting in lost teaching time.

The system should be able to isolate the gas in the event of a genuine fire alarm. The system should also have provision for the connection of heat detectors, as referred to in BB100 3.1.8. Any system should be capable of differentiating between a power loss and a potential emergency isolation, so that a subsequent auto restart can be allowed safely.