Air conditioner buying guide: tonnage, inverter and star ratings

Tonnage: match the AC to the room, not the budget

An AC that is too small runs at full power all afternoon and still cannot cool the room; one that is far too big wastes money. As a starting point: up to about 120 sq ft needs around 1 ton, 120–180 sq ft about 1.5 ton, and 180–250 sq ft about 2 ton.

Go one step up if the room is on the top floor, faces west, has large windows, a kitchen nearby or many people in it. In very hot cities, a 1.5 ton AC in a 150 sq ft top-floor bedroom is a common, sensible choice.

Inverter or fixed speed

An inverter AC changes its compressor speed instead of switching on and off. It keeps the temperature steadier, is quieter, and uses noticeably less electricity when it runs for many hours a day. If you use the AC for more than a few hours daily through the summer, an inverter model pays back its extra price. Almost all new split ACs in India are inverters now.

Star rating and the electricity bill

BEE star labels show how efficient an AC is, and the label shows its year – the rules are tightened from time to time, so a 5-star AC from an old label may equal a 3-star one today. Compare the yearly units (kWh) printed on the label rather than only the stars.

A 5-star AC costs more upfront. If you run it 8–10 hours a day for many months, the saving adds up within a few years; for occasional use, a 3-star inverter is usually the better value.

Copper coils, filters and features that matter

Copper condenser coils are easier to repair and generally last longer in coastal, humid air than aluminium ones. Washable filters, a dust filter you can reach easily and an auto-clean or "self-clean" mode help keep cooling strong. Convertible modes (running at 40–80% capacity) are useful to save power on milder nights. Wi-Fi control is a nice extra, not a necessity.

Installation: the hidden cost

Standard installation is often free, but the copper pipe beyond the included length, the outdoor unit stand, drain pipe and core cutting are usually charged extra. Ask for the rate card before the technician starts. Check whether the AC works without a stabiliser in your area's voltage range, and note the compressor warranty (often 5–10 years) separately from the product warranty.