37 Installation, repair, maintenance, servicing and reconditioning of apparatus for monitoring, apparatus for measuring, apparatus for checking, instruments for monitoring, instruments for measuring, instruments for checking, apparatus for condition monitoring, instruments for condition monitoring, detection apparatus, detection instruments, remote monitoring apparatus, air monitoring apparatus, air measuring apparatus, air analysis apparatus, and air pollution measuring devices; installation, repair, cleaning, maintenance and servicing of ventilation installations, ventilation apparatus, ventilation terminals, ventilation hoods, industrial ventilation apparatus, fans, electric fans, electric fans for ventilation, motorised fans for ventilation, fans for use in air conditioning and ventilation, air inductor apparatus, turbine ventilators, extractors, extractor fans, air humidifying installations, air humidifying apparatus, air cleaning instruments, air cleaning apparatus, air purifying installations, air purifying apparatus, air handling installations, air handling apparatus, air conditioning systems, air conditioners, air conditioning filters, air filters, air humidifiers, air moisturisers, air sterilisers, air purifiers, air dehumidifiers, air ionization apparatus, air control dampers, air freshening installations, air freshening apparatus, filters for air conditioning installations, filters for air conditioning apparatus, filters for air ventilation installations, filters for air ventilation apparatus, air deodorising installations, air deodorising apparatus, air circulation apparatus, air circulation installations, air recircling installations, air recircling apparatus, and air distribution units; HVAC installation, maintenance and repair; installation, maintenance and repair of heating, ventilation and air-conditioning [HVAC] systems; information, advisory and consultancy services relating to all of the aforementioned services