ATEX-compliant HVAC system provides all-in-one automatic climate control for walk-in style process analytical instrumentation shelters. Customizable and scalable to suit diverse applications, unit handles ventilating, heating, cooling, dehumidifying, air filtering, purging, and pressurization within hazardous area up to zone 1. Heating and cooling capacities are available from 6 kW upwards, and system can be supplied fully integrated within shelter or as external standalone unit.