A steam-cleaning trial on kitchen exhaust ducts usually takes an hour or two and leaves the kitchen no better off than before it started. The crew shows up, runs steam over the visible hood surfaces, and the operator signs off. Weeks later the same grease film is back on the filters, and nobody can say whether the trial proved anything about the equipment or the method. The reason is simple: the trial was judged on how clean the surfaces looked rather than on what the process actually removed, how long it took, and what it would cost to repeat.
If you are the operations or facilities lead reviewing that trial, the job is to convert a demonstration into a decision. Below is the review checklist we suggest walking through before you authorise a full duct, hood and fan clean — and the questions to put to any vendor who comes back with a proposal.
1. Check what was actually reached, not what was reached easily
Grease builds up fastest where airflow slows: the far ends of horizontal duct runs, the elbow before the fan, and the fan housing itself. Those are the hardest sections to reach and the ones most often left out of a short trial. Before the trial ends, ask the crew to show you which sections were opened and which were cleaned in place. A trial that only covered the hood face and the first metre of duct is a cosmetic result, and it tells you nothing about whether the machine can handle a grease-laden interior run.
Write the covered sections down on the site drawing. When you later compare quotes, that drawing is the only fair basis for comparison, because vendors price the sections they can reach cheaply and quietly leave the rest out.
2. Look at the residue, not the shine
Stainless steel looks clean long after it is safe. After the trial, run a fingertip or a white cloth along a gasket line, the filter frame, and the underside of the hood lip. Soft, oily film that transfers means the emulsified grease was never fully rinsed and removed — it will re-harden within days and the surface is back where it started.
Two details decide this. First, whether the machine holds its steam temperature and pressure through the whole job, or fades as the tank and lines cool. Second, whether the operator matched the mode to the surface. A dry and wet steam cleaner gives you that choice: drier steam breaks thick, aged coating without flooding the surface, wetter steam flushes the loosened residue off horizontal runs. A trial run in one mode only does not show what the same machine does on a mixed coating, so ask for a short pass in each mode on one section and compare.
3. Time the trial against your service window, not against the crew's schedule
Most kitchens can release extraction equipment for a narrow overnight or early-morning window, and everything outside that window is downtime you pay for twice. Record three timings from the trial: machine warm-up before the first pass, actual cleaning time per section, and the time needed for surfaces to dry before cooking resumes. Add the walk-down and reassembly time.
If warm-up plus drying eats most of the window, the machine is undersized for the job or the sequence is wrong, not the kitchen. That single number decides whether a full clean fits your operation at all, and it is worth more than any claim in the vendor's brochure.
4. Confirm equipment compatibility before anyone talks price
Trial equipment sitting in a loading bay tells you little. What you need to confirm, on your own site, is whether you have 220 V power at the access point, whether there is a water feed and a legal route for rinse-water disposal, and how far the machine has to be moved between duct access points. For a fixed installation on a repeated programme, our 220V steam cleaning machine HW02 runs on tap water with a 4-point internal-tooth inlet and 220 V supply, and its parameters are published on the product page — 6 kW heating power, 160° steam temperature and 0.8 MPa vapour pressure with an 80 L SUS304 tank. Check your supply against those figures rather than assuming a match.
Ask the vendor to name the protection features they rely on when a machine is running unattended near electrical equipment — leakage, short-circuit, high-temperature, high-voltage and water-shortage protection are the items listed for the HW02. If a proposal cannot name them, you are being offered a pressure washer with a steam label on it.
5. Test the documentation, because that is what an inspector reads
Ask for the trial record the day after the crew leaves. It should name the date, the sections covered, the method used per section, and a before-and-after note signed by whoever supervised the work. If the paperwork arrives a week late and half the fields are blank, a full contract under the same vendor will produce the same paperwork — and that is the paperwork your fire-risk assessment, your insurer and any hygiene inspection will ask for.
A practical test: read the trial record without the crew present. If you cannot tell from it which sections were cleaned and how, it is not fit for the purpose, whatever the crew says.
6. Price the interval, not the visit
A single visit number is the easiest thing in a proposal to mislead you with. What you need is the interval the trial supports. On the trial sections, mark the date and check at two weeks, four weeks and eight weeks. Where grease is visibly returning, that section needs a shorter cycle, and a steam method that shortens the cycle changes the annual cost even if each visit is more expensive.
Ask the vendor to state, in writing, the interval they believe the trial justifies for your ductwork — and to say what they observed that supports it. An answer of "as often as you like" means they have not read the results either.
7. Run the safety walk-down before you sign anything
Hot steam and hot surfaces around an operating kitchen carry obvious hazards, so review how the trial crew actually behaved: were access panels locked out and tagged, was the area signed and cordoned while the machine was live, was the electrical supply protected, and where did the run-off go on your floor drains. Note any place the crew cut a corner because your site made it easy to do so. Then check the machine's own limits — the protection items above matter less in the specification than in how the operator is allowed to work.
If your kitchen runs cleaning in-house rather than with contractors, this walk-down is also the moment to decide whether your own staff can repeat the sequence safely without supervision. If they cannot, budget for the contractor rather than the machine.
Before the next trial: three things to fix
First, scope the trial on paper before the crew arrives, and name the difficult sections in it. Second, nominate one person to record timings, coverage and residue findings while the work is happening — not afterwards. Third, decide the pass criteria in advance, so the decision is made against a standard rather than against a clean-looking hood.
If your trial shows that coverage, timing or documentation were the weak points rather than the method itself, talk to us about what a commercial steam cleaning equipment programme for kitchen extraction should include, and what we can confirm from your own site conditions before any equipment is quoted. Send your duct layout and access points to sales@powerde.net, or call +86 13023198376, and we will review it against the HW02 specification and your power and water supply.
