What the question is really asking
When a kitchen exhaust hood is sent out for degreasing, the operator usually arrives with a pressure washer, a drum of detergent and a shop vac, and the invoice records labour hours. Almost nobody records water. That omission costs money twice: once in the bill for the water you used and discharged, and once in the downtime that follows a washdown that left the housing, the electrical enclosure and the floor around it wetter than the finish can tolerate.
Water use in hood cleaning is measurable with equipment you already have. What you need is a defined job boundary, a meter on the water supply, and a waste route you can inspect. A commercial steam cleaning machine changes that arithmetic because steam carries heat in a very small volume of water, and a machine with vacuum recovery lifts the loosened grease off the surface instead of washing it into the drain.
Define the job before you measure anything
A "hood cleaning" can mean three different scopes, and the water figures are not comparable between them. Write down which one you are buying or performing:
- Canopy and filters only. The accessible interior face of the canopy, the grease filters and the filter trough. This is the shortest job and the one most frequently repeated.
- Canopy plus upper duct. The first metres of duct, the fan housing where it is reachable, and the access panels. More reach, more rinsing, more runoff.
- Full extract path. Filters, canopy, duct run, fan and terminal. On this scope the water decision is no longer a cleaning question but a building question, because the duct has to be dried before the extract fan is restarted.
Record the scope, the hood linear metres, the surface type (stainless, galvanised, painted), and the soil condition you find at the start: soft surface grease, sticky oxidised residue, or baked carbonised deposits. Soil state drives the method, and the method drives the water.
Three ways to put a number on the water
1. Meter the supply
Fit an inline turbine or paddle wheel meter on the hose reel or tap serving the cleaning task, and log the reading before and after each hood. For teams without a meter, a bucket, a stopwatch and the time to fill it give you the flow rate in litres per minute; multiply that by the trigger time on the lance. Do the test twice, on a similar hood, and you have a repeatable figure rather than a guess.
2. Weigh or measure the waste
Water that leaves the surface has to go somewhere. Measure what you collect in a recovery tank, or time how long the floor drains run after a job. Where recovered volume and supplied volume differ sharply, the gap is water you sent into the drain, into the ductwork or into the wall cavity. That gap is the number worth reducing.
3. Count the indirect costs
Water volume alone understates the cost. Add the labour minutes spent rinsing and squeegeeing, the shutdown of the cooking line while the hood dries, and any electrical or bearing work caused by water ingress. Those lines are where a low-volume method earns its keep even when the water tariff is modest.
Where water is actually spent on a hood
On a high-volume washdown the water goes to four jobs, and only the first one is essential:
- Soaking and flushing. Running water over the surface to carry soil away.
- Heat. Hot water to soften hardened grease. Most of the water is being consumed simply to deliver temperature.
- Rinsing detergent. Every litre of detergent has to be rinsed off a surface that touches food service.
- Drying. Time and labour spent getting the housing and the surrounding area back to a safe, dry condition.
Steam attacks the second item directly. Vapor at temperature is delivered in a fraction of the volume a hot-water lance uses, so the heat arrives without the soak. A central kitchen hood degreasing machine such as the PowerDe HW02 steam cleaner is specified on its detail page at 160 degrees steam temperature, 0.8 MPa vapor pressure, 6 kW heating power, an 80 L SUS304 tank fed from a tap-water inlet, dry and wet steam selection and an integral vacuum cleaner on a 220 V supply. Read those parameters as a water budget: the tank sets the volume carried to the job, and the vacuum recovery decides how much of the loosened residue is lifted into a tank instead of flushed toward the drain.
Do not look for a savings percentage in that specification, and do not accept one from a supplier. Consumption per hood depends on soil load, operator technique, and how many passes the residue needs. What the specification gives you is the inputs for your own measurement: tank volume, mode selection, and recovery.
Comparating methods on the same hood
Run a side-by-side trial on two identical hoods under the same shift conditions, or on the same hood at the same soil interval, and record the six lines below. This is the comparison a facilities or procurement review can act on.
| Measured line | Why it matters |
|---|---|
| Triggered water volume, litres per hood | The direct supply and discharge cost. |
| Operator minutes to a signed-off surface | Usually the largest single line on the invoice. |
| Detergent volume and number of rinse passes | Chemical cost plus the rinse water it forces. |
| Recovered waste volume versus supplied volume | Shows where the missing water went. |
| Time until the cooking line can restart | Downtime, not cleaning time, decides the schedule. |
| Rework visits within the same period | A method that misses baked residue is paid for twice. |
Inspect the result rather than admiring it. Lift an access panel and check for standing water in the trough and behind the fan housing. Wipe the interior of the electrical enclosure and confirm it is dry. Look at the sheen on the stainless: a smeared film means the soil was moved, not removed, and the next clean will be harder.
Constraints that decide whether steam is the right tool
- Electrical enclosures, motors and bearings. Keep directed heat and vapor away from the fan motor, its bearings and any junction box. Where the fan and wiring must be cleaned, plan the sequence so those parts are protected or isolated first, and confirm the machine's rated supply with your electrician.
- Supply voltage and installed capacity. A fixed unit's heating load needs a matching circuit. Check the socket, the breaker and the run length before the crew arrives, not at 11pm on a service night.
- Duct integrity and building rules. Water into a duct run is a mould and structural problem, not a cleaning problem. Follow whatever fire and hygiene regime your site operates under, and let the duct scope be set by whoever signs the fire safety record.
- Hot surfaces and vapour handling. Steam at temperature in an enclosed canopy is a burn hazard and displaces air in tight spaces. Ventilate, allow the surfaces to cool, and use the tool with the hood de-energised.
- Water quality. A tap-water inlet on a hard-water site will scale a heater. Ask the supplier what treatment they recommend for your installation before the warranty question comes up.
A short specification checklist for the enquiry
- Supply voltage, heating power and the circuit you actually have available.
- Stated steam temperature and vapor pressure, and whether dry/wet steam can be switched at the wand.
- Tank volume and tank material, and whether the inlet connects to mains water.
- Vacuum recovery included, with a recovery tank that can be emptied and rinsed after each job.
- Floor, crevice and extension tooling in the package, plus spare seals and nozzles on site.
- Warranty, wear-part pricing and the lead time for spares.
If your hoods run continuously and the clean has to happen between services rather than overnight, the standard catalogue answer may not fit your layout. PowerDe lists customized steam cleaning equipment as an engineering service, covering machine configuration and application-specific setups.
Send the factory your hood length, photos of the worst corner, your shift window, your available supply details and one set of the measured figures above, and ask them to propose the model and tooling set that fits those inputs. The number that decides the case is your own water and labour data, so collect it before the quotation, not after.
