Size it to the water surface
The figure that matters is how many litres of water a day the machine removes, and the load depends on the area of water, how warm it is and how long it stays uncovered. As a rough guide, a portable machine of around 65 to 85 litres a day suits a hot tub or spa room or a small pool kept covered, while a larger pool, or one left open, needs more capacity or a second machine.
Portable or fixed in place
A portable machine stands on the floor, plugs into a socket and usually drains by gravity through a hose to a floor drain, so it can be moved or stored out of season. A fixed system is wired and plumbed in permanently and keeps the poolside clear, which suits a pool used all year round.
Wiring, drainage and running costs
Pool rooms have their own wiring rules, so keep plug-in machines and sockets well back from the water and have a qualified electrician connect fixed units. A pool cover, and air kept about 1 to 2°C warmer than the water at around 60% humidity, cut evaporation and running costs. The machine gives the heat it pulls out of the damp air back to the room, and its dust filters want a rinse every few weeks.
