— Understanding the figures
AirWatts. Water lift.
Two figures, one question.
Is your vacuum powerful?Does it really pull?And for how long?
— The principle
Power and suction.
They are not the same thing.
A vacuum is a motor doing two things: moving a lot of air (power), and creating a vacuum that lifts the dust (suction). Two jobs, two measurements. Serious manufacturers give both, because a very powerful machine can still clean poorly if its suction is weak — and vice versa.
— Power
AirWatts: the real cleaning power.
The AirWatt measures the useful power actually available at the end of the hose — not the motor's electrical consumption. It's the only unit that compares two vacuums honestly, because it accounts for both airflow and water lift at once.
In concrete terms, power (W) = airflow (l/s) × vacuum (kPa). The industry's "AirWatt" unit is built on this very calculation.
Airflow
It's the amount of air moved — the current that carries dirt down the pipes. In plain terms: how fast dust and debris race toward the central unit.
Water lift
It's the raw pulling force of the suction, the grip of the motor. It's what tears out ingrained dirt and lifts heavy debris. (It's measured in mmH₂O — see below.)
| Appliance | Useful power |
|---|---|
| Standard vacuum cleaner | 280 to 300 AW |
| AspiWall S100 | 600 AW |
| AspiWall S400 | 695 AW |
| AspiWall S500 | 1,354 AW |
The AspiWall S500 is presented by its manufacturer Trovac as the most powerful domestic central vacuum in the world.
— Suction
Water lift (mmH₂O): how hard the air is pulled.
Water lift (mmH₂O — millimetres of water column) measures the vacuum, i.e. the suction force. Picture a vertical tube filled with water: the higher the unit can "pull" the water column, the stronger the suction. It's the measurement that tells you whether dust, hair or heavy debris will really lift off the floor.
| Appliance | Suction force | Vacuum (Pa) |
|---|---|---|
| Standard vacuum cleaner | ~1,500 mmH₂O | ~14,700 Pa |
| AspiWall S100 | 3,033 mmH₂O | ~29,700 Pa |
| AspiWall S400 | 4,318 mmH₂O | ~42,300 Pa |
| AspiWall S500 | 6,452 mmH₂O | ~63,300 Pa |
Pa is the unit robot vacuums quote — handy for comparison: they range from ~2,700 to ~25,000 Pa depending on the model — even their maximum stays below our ~63,300 Pa (S500).
— The test
Where does your vacuum stand?
Enter the power of your current vacuum (in AirWatts, often listed in its manual — usually 250 to 350 AW for a classic model). We'll show you where it lands against our range.
Indicative estimate based on manufacturer useful-power figures.
— Common sense
Power alone = wind.
Suction alone = a blockage.
Lots of power without suction is a fan: the air moves but lifts nothing. Lots of suction without power is a bottleneck: the air pulls hard at one spot but the network chokes as soon as dust builds up. A good central unit balances the two — which is why AspiWall always shows both figures for every model.
— Comfort
Silence isn't measured in AW.
AirWatts and water lift tell you the strength of the suction, not the comfort. The real quiet of a central vacuum comes from elsewhere: the unit is installed in the garage, the basement or a utility room, not in the room where you live. You only hear the airflow in the hose — between 59 and 65 dB in use, against 70 to 80 dB for a standard vacuum in the same room.
— Frequently asked questions
Your questions. Our answers.
Should I look at AirWatts or water lift (mmH₂O) to choose?
Both. AirWatts compare overall useful power; water lift (mmH₂O) compares raw suction force. For a home with pets, rugs or several floors, aim for a good balance between the two rather than a single high figure.
Why don't all brands quote AirWatts?
Because power consumption (in Watts) or motor power always makes for a bigger number — but that isn't the useful power. The AirWatt is the only honest, customer-facing measure.
Is water lift (mmH₂O) the same as Pascals or kPa?
It's the same measurement in a different format. 1,000 mmH₂O ≈ 9.81 kPa ≈ 9,810 Pa. Water lift (mmH₂O) is the traditional unit of the central vacuum industry.
Is higher always better?
Not only. Beyond a certain threshold, extra power and suction bring little benefit — that's why AspiWall sizes every central unit with a 50% capacity reserve, so the network is never saturated and airflow stays constant over time.
The right figures for your home.
Send your floor plans and get a personalised quote. AspiWall sizes the unit you need.