The wear marks scored into the sides of that pit tell the story clearly enough: a large overshot waterwheel, fifteen feet in diameter and five feet wide, once turned here, fed by water drawn from a mountain stream through a millrace weir roughly 350 metres to the south. An overshot wheel is one where water is delivered to the top of the wheel rather than the bottom, giving it considerably more power than other designs. That original wheel is long gone, replaced at some point by a modern pelton-type turbine, a device that uses high-velocity jets of water rather than the weight and flow of a wheel. Most of the gearing and internal machinery has also been removed, though one bedstone, the lower of the two millstones used for grinding grain, remains in place on the first floor.

The 1842 Ordnance Survey six-inch map identifies this site as both a flour mill and as 'Millvale Co', suggesting it was operating as a commercial concern by the mid-nineteenth century. The attached three-bay, three-storey building known as Millvale Cottage sits at the north-western side of the mill's north-eastern end, indicating that the site was substantial enough to house those connected with its running. According to a more recent owner, the mill was worked as a flax mill by his grandfather, which points to a different industrial function at some point in its past. Flax milling, used in the processing of fibres for linen production, was common across Ireland during the eighteenth and nineteenth centuries before the industry contracted. The site also holds a collection of machinery salvaged from other mills, among them a Vickers Peters oil engine, a cast-iron saw bench, and two hydraulic rams made by Evans and Vulcan, giving it something of the character of an informal industrial museum.