The outdoor unit is much the same whichever way you go. The decision that affects your house is the indoor unit: what it looks like, where it can go, and how much building work it takes to get it there. Here are the real differences between the three main types, including the honest reasons two of them are wrong for most homes.
In this guide
The three you will actually be offered
Strip away the brochures and there are three families of indoor unit. Wall mounted, which hangs high on a wall. Cassettes, which sit flush in a ceiling. And ducted, hidden entirely, blowing through grilles you barely notice.
They all do the same job, using the same refrigerant and the same outdoor unit. What differs is how visible they are, how the air is distributed, and how much of your building has to change to accommodate them. That last one is where the money is.
Wall mounted
The familiar white box, high on the wall. It is what most people picture, and what goes into the large majority of the homes we do across Teesside.
- It is the most affordable option, on the equipment and the labour.
- It is the quickest to fit. A bracket, a core hole and the pipework. No ceiling work, no structural thinking.
- It suits almost any room with a sensible external wall available.
- It is easy to live with. Filters slide out of the front panel in seconds, which matters, because the filter is the one bit of maintenance that is yours.
- It is visible. No getting round that. It is a white box on your wall, and some people mind.
- It blows from one end of the room. Fine for most rooms, less good for a long one.
If you are not sure what you want, this is almost certainly your answer, and we will say so even though it is the cheapest thing we fit.
Ceiling cassettes
A cassette sits up in the ceiling with only a flat grille visible below, pushing air out in several directions at once. You have almost certainly stood under one in a shop without registering it.
The advantage is distribution. In an open plan space, or a room much longer than it is wide, blowing from the middle of the ceiling in four directions is far more even than blowing from one end. That is why they dominate commercial work, and why our guide on air conditioning for offices keeps returning to them.
The honest catch for a home is that they need a ceiling void. There has to be real space above the ceiling for the unit, the pipework and the drainage, and in most British houses there is not. Where it works is a suspended ceiling, a garage conversion, or an extension being built now. If your ceiling is a plasterboard skin under joists with a bedroom on top, this is not your option, and wanting it does not change that.
Ducted and concealed
The invisible one. The unit hides in a loft, a ceiling void or a bulkhead, and the air reaches the room through ductwork and discreet grilles. Done well, you would not know the house had air conditioning.
It is genuinely the best looking answer, and right for a specific set of situations: a home where appearance is the priority, a room with no usable wall, or one hidden unit serving several rooms.
It is also the most expensive and most disruptive by a distance, and the reason is not the equipment. Ductwork has to go somewhere. That means loft space or bulkheads, grilles cut into ceilings, and building work rather than a bracket and a hole. Access matters too: the unit is hidden and it still needs servicing, so there has to be a sensible way to reach it, designed in from the start rather than regretted later.
The plain advice is that ducted makes most sense when you are already doing the building work. In a renovation or a loft conversion the disruption is happening anyway. Retrofitting it into a finished house is a big undertaking for an aesthetic gain, and we would want your eyes open going in.
The ones in between
The three types are the map, not the territory. Manufacturers make a few things that sit between them, and one may be the answer for an awkward room.
- Floor standing units. They sit low, like a radiator, and throw air upwards. Useful where there is no high wall, and a common answer in a conservatory with a dwarf wall.
- Low wall units. The same idea, mounted low rather than high, and often chosen for the same reason.
- Low profile and designer wall units. A slimmer box that draws less attention. It costs more and it is still on the wall.
- Ceiling suspended units. Fixed under a ceiling rather than in it. Rare in homes, occasionally right in a long room with no void.
Three questions that decide it
In practice the choice comes down to three things, in this order.
- What does your building physically allow? No ceiling void means no cassette. No loft access means no ducted. This one usually answers the whole thing.
- How much does appearance matter to you? Be honest with yourself. Plenty of people say a white box would bother them and stop noticing it inside a fortnight. Some never stop noticing it. Only you know which you are.
- What shape is the room? A square bedroom is happy with a wall unit. A long open plan space with a wall unit at one end will always be warmer at the far end.
Notice budget is not on that list. Budget decides whether you do the job, not which type is right. If the building allows only one answer, a bigger budget does not create the ceiling void.
What each one costs you
We quote after a survey, so there are no numbers here. What is useful is what each type costs you beyond the price, because that is the part nobody thinks about until it is happening.
- Wall mounted costs you a visible unit and a straightforward day of work.
- Cassette costs you ceiling work, and costs you the option entirely if the void is not there.
- Ducted costs you the most money, the most days, the most building work, and easy access for maintenance unless that is designed in from the start.
- All of them cost you an annual service, which most manufacturers require to keep the warranty valid whichever type you choose.
The pattern is consistent. The less you can see of it, the more of your house it goes through to get there.
What the type does not change
Worth being clear about, because the brochures are not. A more expensive indoor unit does not make the system better at its job.
- It does not make it more efficient. Efficiency comes from the system, the sizing and the installation, not from how the unit looks.
- It does not make it cheaper to run. A correctly sized wall unit beats an oversized ducted one every day of the week.
- It does not remove the outdoor unit. There is still a box outside, and where it goes is still the question that matters most.
- It does not reduce the maintenance. If anything, a hidden unit makes servicing harder.
- It does not fix a bad design. An invisible system that is the wrong size for the room is still the wrong size.
Is the expensive one better?
No, and this is the one place we will be blunt. Ducted is not an upgrade. It is a different answer to a different problem: not wanting to see the equipment.
If that problem is real for you, it is worth solving and we will solve it properly. If it is not, the money is better spent getting the sizing right, or doing the second room at the same time as the first. A correctly specified wall mounted system in two rooms will do more for your life than a beautifully hidden one in a single room. We say that knowing which of those two quotes is bigger.
Deciding at survey
You do not need to have decided before you call us. Half of this is a building question, and you cannot answer it from a website, because it depends on what is above your ceiling and what your walls are made of.
At survey we tell you what your house allows, show you the realistic options for each room, and explain what each means for the price and for the day. Then you choose, with the trade offs on the table rather than buried in a specification. We are a family business on North Ormsby Road in Middlesbrough, covering roughly twenty miles of Teesside from Stockton on Tees, Thornaby, Billingham and Norton across to Yarm, Eaglescliffe, Ingleby Barwick, Redcar, Marske, Saltburn, Guisborough, Marton, Hartlepool, Peterlee and Darlington. The survey is free. Call 01642 680 873.
