MMC Klima · Glossary
Air conditioning glossary
Every word on the label, in the brochure and in the conversation with the technician, explained in two sentences with a link to the guide that covers it.
BTU/h (British Thermal Unit)
- A unit of cooling and heating capacity. 1 kW = 3412 BTU/h; 9000 BTU ≈ 2.6 kW, 12000 BTU ≈ 3.5 kW, 18000 BTU ≈ 5.3 kW. Rule of thumb: 100–120 W per square metre. More
Inverter compressor
- A compressor with continuously variable speed. Instead of cycling on and off, the unit holds the temperature at low speed: quieter, cheaper to run and longer-lived. More
SEER (seasonal energy efficiency ratio, cooling)
- How many kWh of cooling the unit delivers per kWh of electricity, averaged over a cooling season at varying load. A++ needs SEER 6.1–8.5, A+++ above 8.5. More
SCOP (seasonal coefficient of performance, heating)
- The same for the heating season. SCOP 4.6 means 4.6 kWh of heat per kWh of electricity. Decisive for the bill if the unit heats in winter. More
EER and COP
- The older single-point efficiency ratios (35°C cooling, 7°C heating). Higher is better, but SEER/SCOP describe real operation more accurately.
Energy class (A+++ … D)
- The EU label class, set by SEER (cooling) and SCOP (heating). An air conditioner has two separate classes, e.g. A++ / A+. More
Pdesign (design capacity)
- The capacity in kW at which the label was calculated. Use it for sizing instead of marketing BTU figures.
Split system
- An air conditioner in two parts: an indoor unit (coil and fan) and an outdoor unit (compressor and condenser) joined by a pipe run. The most common domestic type. More
Multi-split
- One outdoor unit connected to 2–5 indoor units with independent control. The answer for several rooms with one possible outdoor location. More
Monoblock
- All components in one housing. For air-to-water heat pumps the monoblock sits outside and feeds hot water into the house; for air conditioners it is a wall unit with no outdoor unit. More
Indoor unit
- The part in the room: coil, fan, filters, louvers and electronics. Wall, cassette, ducted, floor or ceiling type.
Outdoor unit
- The part outside: compressor, coil, fan and expansion valve. Rejects heat in summer and extracts it from the air in winter.
Pipe run
- The insulated copper pipes, cable and drain between the indoor and outdoor units, usually in PVC trunking. Standard installation includes 3 m; each extra metre is charged. More
Vacuuming
- Pulling air and moisture out of the pipe run with a vacuum pump before releasing the refrigerant. Mandatory for efficiency and for the warranty; "purging with refrigerant" is not a substitute.
Condensate and drain
- The water pulled from the air when cooling, up to several litres a day. It drains through a sloped hose; where there is no natural outlet a condensate pump is fitted.
Refrigerant (R32, R410A)
- The substance that carries heat between the two units. New units use R32: more efficient and with three times lower climate impact than R410A. More
dB(A) (noise level)
- Sound pressure at 1 m from the unit. 19–22 dB in quiet mode is practically inaudible (bedroom); 30+ dB is audible in silence. The scale is logarithmic: +10 dB is twice as loud. More
Hyper inverter
- A compressor with vapour injection and a stronger inverter that keeps heating output at −15 to −25°C. Trade names: Zubadan, Hyper Heating, Nordic, Arctic. More
Defrost
- A short cycle in heating mode in which the outdoor unit stops for 3–10 minutes to melt ice on its coil. Normal, not a fault.
Wi-Fi module
- A built-in or optional module that links the unit to a phone app: remote start, schedules, geofencing, consumption tracking. More
Air-to-water heat pump
- A heat pump that takes heat from the air and delivers it to water: radiators, underfloor heating, fan coils and a hot-water cylinder. A whole-house solution. More
Air-to-air heat pump
- The technical name of every heating air conditioner: it moves heat from outdoor air to room air. SCOP above 4 means heating four times cheaper than a resistive heater.
Ducted air conditioner
- An indoor unit in a suspended ceiling that supplies air through ducts and grilles to several rooms. The invisible option for houses, offices and shops. More
Cassette air conditioner
- An indoor unit recessed in a suspended ceiling with a four-way grille. The standard for offices, shops and restaurants. More
Column (floor-standing) air conditioner
- A high-capacity floor unit (24000–60000 BTU) for halls, shops and industrial spaces without a suspended ceiling. More
Fan coil unit
- A coil-and-fan unit that heats or cools with water from a heat pump or boiler. Replaces a radiator and can cool. More
Air purifier
- A stand-alone unit with HEPA and carbon filters that captures fine particles, allergens and odours. It does not cool or heat. More
HEPA filter
- A filter that retains over 99.95% of 0.3-micron particles: dust, pollen, bacteria. In air conditioners it appears as an additional filter with a limited life.
Dry mode
- A mode in which the unit runs at minimum speed and mainly dehumidifies, with little cooling. Useful in humid, mild weather.
Sleep / Night mode
- Minimum fan speed, display off and a gradual 1–2°C shift of the set temperature, because the body needs less cooling in deep sleep.
Turbo / Powerful mode
- Maximum output for 15–30 minutes to reach the set temperature fast. Not for continuous use: the most consumption and the most noise.
Partial load
- Operation after the temperature is reached, at 20–50% of capacity. Inverters are most efficient here, which is why SEER/SCOP rate them in this regime.
Useful links