The two halves of a split system have almost opposite requirements. The indoor unit wants clear air movement across the room and a discreet position. The outdoor unit wants generous airflow, a solid mounting, distance from bedroom windows and boundaries, and room for an engineer to work.
Reconciling those is the design job, and it is far cheaper to argue about it on paper than after the wall is drilled.
Indoor unit siting rules
- Keep the manufacturer's clearances above and to the sides of the unit — airflow is not optional
- Point the air throw along the length of the room, not straight into a wall or a wardrobe
- Avoid blowing directly at a bed, a desk chair or a sofa where people sit for hours
- Keep it away from a doorway where all the conditioned air leaves the room
- Allow a route for the condensate drain with continuous fall, or plan a pump
- Check the wall can take the bracket load, especially on stud or dot-and-dab construction
Outdoor unit siting rules
- Free airflow into the coil and out of the fan, with no recirculation into a corner or tight recess
- Sensible distance from your own and neighbours' bedroom windows
- Off the ground on brackets or feet, so leaves and standing water stay clear
- Anti-vibration mounts, and never bolted to a lightweight or hollow structure that will resonate
- Room to remove panels and take readings without dismantling fences or trellis
- Somewhere the defrost water can drain away safely rather than freezing across a step
Noise is a siting problem, not an equipment problem
Modern condensers are much quieter than their reputation, but sound behaves badly around buildings. A unit in a narrow side passage between two solid walls will be far more audible than the same unit on an open rear elevation, because the sound reflects rather than dissipating.
The two mistakes we see most are placing a condenser directly under a bedroom window and boxing it into a decorative enclosure with no clearance. The first creates a nuisance; the second creates a nuisance and reduced efficiency at the same time.
How siting gets settled at survey
- 1
Start outside
Identify every position where a condenser could legitimately go, considering airflow, noise, boundaries and access.
- 2
Work back to the room
Find indoor positions that can reach one of those outdoor points with a sensible pipe route.
- 3
Test the route
Check whether the route is concealable through a void or loft, or needs trunking — and agree which.
- 4
Check the drain
Establish whether gravity fall to a suitable discharge exists from the chosen indoor position.
- 5
Confirm the electrics
Verify that a suitable supply can reach the outdoor position safely.
- 6
Then agree appearance
With the technical constraints fixed, the remaining choices are yours: trunking colour, unit format, exact height.
Have your positions surveyed before you commit
We assess indoor and outdoor positions together, including noise, clearances, drainage and service access, then agree the pipe route with you before any work starts.
Get siting right and the system is quiet, efficient and cheap to maintain for fifteen years. Get it wrong and no amount of good equipment will stop you noticing, every single evening.