This custom home in Co. Mayo measures 2750ft2. (263m2). It is fully air conditioned and heated by one small duct high velocity system with inverter driven air source heat pump and a waste oil boiler. The owner wanted to maintain his home at 210C all year round. Given the design brief, EJ Fidgeon specified a small duct high velocity system. The large open plan first floor would have posed a challenge to heat with conventional heating systems such as radiators or underfloor heating. The small duct high velocity system replaces the need for radiators or underfloor heating and gives even temperatures throughout the home. Corner to corner, floor to ceiling there is less than 1C difference from the thermostat setpoint. Air fi ltration and fresh air are standard on this installation. The small supply outlets have been placed above the skirting board in the upstairs living room and the return air grille is located in the side wall. An Aprilaire programmable thermostat for control of the two stages heating and the air conditioning.