- Home
- Ductless
When ductless is the right answer, and when it is a sales pitch
In a house with nowhere to run a duct, ductless is usually the honest answer. In a house with a perfectly serviceable duct system, it is usually not. Both sentences are on this page for a reason.
An outdoor unit, small pipes, and units in the rooms
Instead of moving conditioned air through ducts, a ductless system moves refrigerant through small insulated pipes to units mounted in the rooms themselves. Each indoor unit conditions the space it is in.
The penetration is small
A hole of roughly three inches per indoor unit carries the refrigerant lines, the drain and the control cable. That is the whole reason this works in a building where a duct will not fit.
No duct losses
There are no ducts, so nothing is lost into a crawlspace or an attic. In this climate that is a real advantage, because attic duct losses here are substantial.
Room-by-room control
Each area is set separately. That suits a house where one end is used all day and the other is not, which describes a great many older houses.
The units are visible
A wall unit is on the wall. Some people do not mind at all and some mind a great deal, and it is far better to find out which you are before the install than after it.
Line set covers matter
The pipes have to get from the outdoor unit to each indoor one. Done properly the covers are neat and planned; done carelessly they are the thing you notice every time you walk up the path.
They still need servicing
Indoor unit filters and blower wheels need cleaning, and drains still need to run. A ductless system that has never been touched performs about as well as any other system that has never been touched.
When we will suggest it
- There is no ductwork and no realistic route for any
- Plaster walls with no cavity, or no usable attic
- An addition, sun room or converted garage that the existing system cannot serve
- A house where one end is barely used and heating all of it is waste
- An outbuilding, workshop or small office with no plant of its own
- A room with a genuinely different load from the rest of the building
When we will say no
- Your existing duct system works and simply needs sealing or balancing
- The real problem is a load calculation nobody has done
- Somebody has been told it is always more efficient, with no reference to their building
- It is being proposed instead of finding out why one room is uncomfortable
- You would hate looking at the indoor units, and nobody has asked you
Fixing ducts is cheaper than replacing a system. Where that is the answer, that is what we will quote, even though it is the smaller job.
What separates a good ductless install from a cheap one
- A load calculation per area, not per houseThe whole point of the system is that areas differ. Sizing every head the same defeats it, and an oversized head short-cycles and leaves the room humid.
- Line set routing planned before anybody drillsWhere the covers run, which elevation they are on, and how they get down to the outdoor unit. Agreed with you in advance, ideally with the route marked up.
- Condensate that actually drainsIndoor units drain by gravity where they can and by a small pump where they cannot. A drain that relies on optimism is the commonest fault we are called to on these systems.
- Proper evacuation before chargingMoisture and air left in the lines damage the system slowly and invisibly. It is the step that is skipped when somebody is in a hurry, and you cannot see whether it was done.
- Outdoor unit mounted clear of standing waterSavannah gets serious rain. Ground-level equipment sitting in a spot that floods has a short life for an entirely avoidable reason.
- Commissioning numbers written downLine pressures, temperatures and the charge, per system, handed to you at the end.
What we will not claim about ductless
That it is always more efficient. That it will pay for itself in a stated number of years. That it will cut a stated percentage off your bill. All three depend on your building, your tariff, your habits and what it is being compared against, and none of them can be known from a website.
What we will say is that in a building with no realistic duct route, the comparison is not usually ductless against ducted. It is ductless against window units, against a room nobody uses, or against building work costing several times more. Put like that the decision is generally easy.