Quick answer
Very quiet. Haier rates its 2.5kW Revive Plus indoor unit at 18 dB(A) on its quietest setting: quieter than rustling leaves and well below a whisper. On full fan it is about 37 dB(A), like a quiet library. The noisy part, the compressor, sits in the outdoor unit outside, at about 49 dB(A) for a single room.
Decibels in plain English
A decibel figure on its own means very little to most people, so here is the one rule worth knowing: every 10 dB sounds about twice as loud. That means:
- Silent mode (18 dB) sounds about a quarter as loud as a humming fridge (40 dB).
- Full fan (37 dB) sounds about ten times quieter than a washing machine (70 dB).
- A hairdryer (about 90 dB) is in a different league altogether.
The “(A)” in dB(A) means the figure is weighted to match how the human ear hears, which is why it is the right number for comparing everyday sounds.
How loud is the indoor unit?
These are Haier’s published sound pressure levels for the wall-mounted Revive Plus units we fit, at each of the four fan speeds. Haier quotes the same figures for heating and cooling.
| Fan setting | 2.5kW indoor (AS25RBAHRA-3) | 3.5kW indoor (AS35RBAHRA-4) | Sounds like |
|---|---|---|---|
| Quietest (silent) | 18 dB(A) | 18 dB(A) | Quieter than rustling leaves |
| Low | 28 dB(A) | 29 dB(A) | Softer than a whisper |
| Medium | 32 dB(A) | 33 dB(A) | A whisper |
| Highest | 37 dB(A) | 38 dB(A) | A quiet library |
What you actually hear is a soft rush of air, not a motor. The indoor unit has no compressor; it is a fan blowing gently across a coil. Once the room is up to temperature the fan slows right down, so most of the time it sits at the quiet end of that table.
Can you sleep with it on?
Yes, and many of our customers fit one specifically for the bedroom. A few things make it even quieter at night:
- Silent or sleep mode. Drops the fan to its lowest speed and eases the temperature gently overnight.
- Aim the air away from the bed. The louvres can be set to blow along the ceiling or towards the window, so you feel the room warm or cool rather than a draught.
- Right-sized unit. A unit sized correctly for the room runs at low speed most of the time. We size every room at survey.
- Keep the filters clean. Clogged filters make the fan work harder and louder. We show you how at handover, and check them at every service.
See bedroom air conditioning for more on cooling and heating a bedroom.
How loud is the outdoor unit?
The outdoor unit is where the compressor and the larger fan live, so it is the louder half of the system. Haier’s rated sound pressure levels:
| Outdoor unit | Rated sound pressure | Roughly like |
|---|---|---|
| Single room, 2.5kW (1U25) | 49 dB(A) | Quiet conversation, close up |
| Single room, 3.5kW (1U35) | 51 dB(A) | Quiet conversation |
| Two or three rooms (3U55) | 51 dB(A) | Quiet conversation |
| Three rooms (3U70) | 53 dB(A) | Moderate rainfall |
| Four or five rooms (4U75 to 5U105) | 55 dB(A) | A quiet office |
Sound drops quickly with distance: in open air, every doubling of distance takes about 6 dB off. Walls, fences and the house itself block more. At survey we choose a position away from bedroom windows, yours and your neighbours’, and mount the unit on anti-vibration feet or a bracket so it does not hum through the wall.
Normal sounds you might notice
- A soft click or tick when heating starts or stops: the plastic casing expanding and contracting with temperature.
- A gentle hiss or trickle: refrigerant moving through the pipes.
- A short whoosh outside in cold weather: the outdoor unit running a defrost cycle for a few minutes, sometimes with a little steam. Heating then carries on as normal.
Rattles, grinding or a loud buzz are not normal. Give us a call and we will take a look.
Want a quiet unit in your bedroom? Get an itemised price in about two minutes, then a free survey where we choose the quietest positions for both units.
Get an instant quoteCommon questions
- How loud is an air conditioning unit in a bedroom?
- A Haier 2.5kW Revive Plus indoor unit is rated at 18 dB(A) on its quietest fan setting, which is quieter than rustling leaves and well below a whisper (about 30 dB). Even on full fan it is about 37 dB(A), similar to a quiet library.
- Can you sleep with air conditioning on?
- Yes. On silent or sleep mode the indoor unit runs at around 18 dB(A), and the noisiest part, the compressor, is in the outdoor unit outside. Most people find a well-installed unit quieter than a fan or a plug-in heater.
- How loud is the outdoor unit?
- Haier rates the 2.5kW outdoor unit at 49 dB(A) and the multi-split outdoor units at 51 to 58 dB(A), roughly the level of quiet conversation close up. Sound drops quickly with distance, and we position the unit at survey with neighbours’ windows in mind.
- Is a heat pump noisier in heating mode?
- Not noticeably indoors; Haier rates the indoor unit at the same levels for heating and cooling. In cold weather the outdoor unit occasionally runs a short defrost cycle, which can make a brief whoosh and a little steam outside. That is normal.
- What is the difference between dB and dB(A)?
- dB(A) is a decibel figure weighted to match how the human ear hears, so it is the right number for comparing everyday sounds. Every 10 dB increase sounds roughly twice as loud.
- Why does my unit click or tick sometimes?
- Small clicks when heating starts or stops are the plastic casing expanding and contracting with temperature, and a soft hiss can be refrigerant moving. Both are normal. Rattles or grinding are not, and are worth a service visit.
Sound figures are Haier’s published sound pressure levels for the Revive Plus range and Haier multi-split outdoor units. Everyday comparisons are typical approximate levels; real-world levels depend on the room, distance and fan setting.