Why Air Conditioning Installation Quotes Vary So Much
You get three quotes for the same split system. Same brand, same capacity, same model number. The prices aren't close.
The natural assumption is that someone is overcharging. Occasionally that's true. Far more often, the quotes are describing two different jobs that happen to end with the same box on the wall.
Key points
- Equipment cost is broadly fixed across installers; labour and installation standard are what vary.
- A correctly mounted indoor unit is near silent — buzzing and rattling are usually mounting faults.
- Evacuation, nitrogen purging, flare torque and weighed-in refrigerant charge decide system life and are invisible after handover.
- Ask about ARCtick licensing, evacuation method, drain termination, fixing points and whether extra refrigerant is included.
The equipment is the one part of an air conditioning installation that's basically fixed — every installer buys the same unit at roughly the same price. Everything that varies is labour, materials, and standard of work. And almost none of that appears on a quote, because there's no line item for "done properly."
Here's what actually differs.
Mounting the indoor unit: the part that decides whether you can hear it
This is the one we get asked about least and it's the one that most affects how you'll feel about the system for the next fifteen years.
A wall-mounted indoor unit sits on a steel backing plate. Manufacturer instructions specify how that plate is fixed — into studs or properly plugged masonry, using all of the fixing points, not the two that are easy to reach. They specify the clearances above and around the unit so air can enter and leave the way it was designed to. They specify that the unit sits level across its width, with the correct fall on the drain.
Doing that takes time. It means finding the studs rather than guessing, packing the plate flat against a wall that isn't flat, and checking it with a level rather than by eye.
Skip it and the unit still works. It just does this instead:
- It hums and buzzes. A plate that isn't hard against the wall at every fixing point lets the fan's vibration transfer into the plasterboard, which then acts as a soundboard. This is the single most common cause of a "noisy" split system, and it's almost impossible to fix afterwards without pulling the unit off the wall.
- It rattles at certain speeds. Vibration that only shows up at one fan speed is nearly always a mounting issue, not a fault.
- It drips. The drain pan relies on gravity. A unit mounted a few millimetres out of level in the wrong direction will overflow into your wall cavity, usually in the second or third summer.
A correctly hung indoor unit is close to silent. That isn't a premium feature — it's the manufacturer's design intent. It just requires someone to spend the extra half hour.
The parts of the job you'll never see
The refrigeration side of the install is invisible once the covers are on, which makes it the easiest place to save time.
Evacuation. Before refrigerant goes in, the pipework has to be evacuated with a vacuum pump to remove air and moisture. Done properly, that's a measured vacuum held and verified with a micron gauge. Done quickly, it's a pump run for a few minutes while the installer packs up. Moisture left in a system reacts with the oil and refrigerant and slowly attacks the compressor from the inside. The failure shows up years later, well after anyone connects it to the install.
Nitrogen purge on brazed joints. Where pipework is brazed, purging with nitrogen prevents oxidisation inside the pipe. Without it, you're leaving carbon scale in the system that ends up circulating through the compressor.
Torque on flare connections. Flare nuts have specified torque figures. Under-tighten and you have a slow leak. Over-tighten and you crack the flare and have a slow leak. Both look identical on day one.
Charge. Longer pipe runs need additional refrigerant, weighed in to the manufacturer's figure. Guessing means the system runs undercharged or overcharged for its whole life, which costs efficiency and capacity in both directions.
None of these are visible at handover. All of them determine whether the system reaches its expected life.
Drainage, electrical and penetrations
- Condensate drain run with continuous fall, no traps or sagging, terminated somewhere legal and sensible — not just out the wall onto the path or into a garden bed against the footing.
- Electrical to AS/NZS 3000, on an appropriately rated circuit, with isolation at the outdoor unit and certification issued.
- Refrigerant handling by ARCtick-licensed technicians. This isn't optional — it's a legal requirement for anyone handling refrigerant.
- Wall penetrations sleeved and sealed properly, on both sides. An unsealed penetration is a water path and a draught, and it's the thing most likely to show up on a building inspection later.
Why it takes us longer
We work to the manufacturer's installation manual for the specific model, not to a generic method. That means the mounting, the clearances, the pipe sizing, the evacuation and the charge are all done to the figures that model was designed around — which is also what keeps the manufacturer's warranty intact if something does go wrong.
It's slower. On a straightforward back-to-back split system it might be an extra hour or two. On a harder install — long pipe runs, double storey, difficult access — it's considerably more.
That's the gap in the quotes.
What to ask before you book anyone
Five questions that will tell you a lot, quickly:
- Are you ARCtick licensed, and will I get an electrical certificate of compliance?
- How do you evacuate the system, and do you use a micron gauge?
- Where will the condensate drain terminate?
- Will the indoor unit be fixed to studs, using all fixing points?
- Is the additional refrigerant for my pipe run included in this price?
An installer who answers these easily is worth paying more for. An installer who's vague about them is the reason cheap installs are expensive.