The equipment purchase gets the attention; the maintenance contract decides what that equipment costs you in year three. This guide is written for the buyer side: the restaurant owner, the operations manager of a small chain, or the property team that inherits a kitchen extraction system with the building. It covers the nine scope line items that must be written down, the cleaning intervals an insurer will ask about, response-time and spares clauses, the reporting that actually satisfies an underwriter, and the red flags to strike out before signing.
Why the Contract Is a Compliance Document, Not a Convenience
A maintenance contract for kitchen extraction is not really about keeping equipment tidy. Three parties read its output: the fire authority that inspects the premises, the insurer that underwrites the fire risk, and the landlord or property manager that owns the duct riser your system connects to. Each of them cares about evidence, not effort. The contract you negotiate must therefore be judged by what it produces on paper, visit after visit.
Cleaning frequency is not negotiable taste; it follows cooking duty. NFPA 96 sets the reference intervals most authorities and insurers work from:
| Cooking duty | Professional cleaning interval |
|---|---|
| Solid fuel cooking (charcoal, wood-fired ovens) | Monthly |
| Heavy duty: 24-hour operations, charbroilers, wok ranges | Quarterly |
| Moderate duty: full-service kitchens, seasonal operation | Semi-annually |
| Low volume: day camps, senior centres, infrequent use | Annually |
Underwriters in the UK follow the same logic through TR19 Grease, which makes deposits measurable: a mean deposit of 200 microns or less across the duct, with any single reading above 500 microns triggering urgent cleaning. The practical point for a buyer is that the contract must produce the evidence these parties want: dated cleaning certificates, deposit readings, and access records. A missing or undated certificate is one of the most common grounds on which a fire claim is contested.
The equipment warranty is the fourth reader. Most manufacturers condition the 12-month whole-unit warranty on documented servicing at the stated intervals. If the contract is silent on who produces those records, the warranty and the service agreement will blame each other precisely when you need both.
Scope: Nine Line Items That Must Be Written Down
Scope disputes are the main reason maintenance relationships fail, so the schedule of work should name every component. Nine line items cover a purification and extraction system end to end:
| Scope item | What the contractor actually does |
|---|---|
| 1. Canopy interior, plenum, grease gutters | Degreased and rinsed; gutters drained and cleared |
| 2. Grease filters (baffle or mesh) | Degreased, inspected, renewed when deformed or past recovery |
| 3. ESP cell | Removed, washed, collector plates inspected, ceramic insulators checked for tracking |
| 4. High-voltage power supply | Output current and voltage recorded at test points against commissioning values |
| 5. Activated carbon stage | Assessed against odour performance; replaced on interval or on saturation |
| 6. Exhaust fan | Impeller degreased, bearings checked, belt tension and vibration recorded |
| 7. Duct interior | Cleaned through access panels; deposit thickness measured and logged |
| 8. Supply and make-up air path | Grilles and filters cleaned; a blocked supply path starves the hood and wrecks capture |
| 9. Documentation | Dated report with photographs, readings, defects list and a cleaning certificate |
Then read the exclusions. Four appear late in practice: access equipment for roof-level fans (lift or scaffold hire), out-of-hours working premiums, grease waste disposal, and report issuance priced per copy. None of these is unreasonable to charge; each becomes a dispute when the contract does not name it. Ask tendering companies to list exclusions explicitly and price them as options, not as surprises at the first visit.
Frequency and Duty: Who Decides the Cadence
A credible contract splits the routine between in-house tasks and contractor visits, and it states the trigger for each:
| Component | In-house routine | Contractor interval | Trigger check |
|---|---|---|---|
| Grease filters | Weekly wash | Inspect at every visit | Hood face velocity |
| ESP cell | None | Wash every 2-4 weeks on heavy duty; about 6 weeks moderate | Pressure drop, arc frequency |
| Activated carbon | Visual check | Assess every visit; replace at 3-6 months | Odour at the discharge point |
| Duct interior | None | Deep clean per the cooking-duty table above | Deposit probe reading |
| Exhaust fan | Visual and listen | Quarterly attention | Vibration, bearing temperature |
For a heavy-duty line, the realistic shape is therefore: contractor visits at 4-6 week intervals covering the purification stages, plus a duct deep clean aligned to the cooking-duty table, plus quarterly fan attention. One visit each year should be scheduled to produce the insurer-facing certificate. If a service company proposes a single annual deep clean for a heavy-duty kitchen, that is a frequency problem disguised as a price advantage: grease accumulates on a monthly scale in a solid-fuel or 24-hour operation, and no annual visit reverses the risk profile in between.
Pricing Structures: Compare Shapes, Not Just Totals
Four pricing structures dominate, and they reward different behaviours:
Fixed price per visit. Best when the scope is stable and the duty is known. Require the task list and visit duration on every invoice so the price stays auditable across the term.
Annual lump sum with included call-outs. Convenient for budgeting, but define what a call-out is: an odour-complaint investigation is not the same event as a recall caused by the contractor’s own missed defect, and only the first should draw down an allowance.
Consumables as pass-through. Carbon, filters, sealing strips and collector plates should be recharged at documented cost with a stated, capped handling percentage. “At list price” is not a pass-through; it is a margin on goods the buyer never sees quoted.
Parts as cost-plus with a cap. State the markup cap as a number, not as “competitive rates”. The same discipline applies to index protection: accept a fixed price for 12 months, then an adjustment tied to a named published index, capped at 3-5%, with 60 days notice and no retrospective application.
Response Times, Spares and First-Time Fix
Response clauses are where contracts look identical on paper and behave completely differently on site. Set the levels by consequence, not by generosity:
| Event | Contracted response | Why it is set there |
|---|---|---|
| Safety event: interlock trip, smoke spilling into the kitchen | 24 hours | The kitchen cannot trade safely on a defeated safety device |
| Odour complaint from neighbours, landlord or regulator | 48 hours | Complaints escalate quickly; the first response is evidence |
| Planned service visits | Fixed calendar, confirmed 10 working days ahead | Protects the staff rota and trading hours |
| Spares fitted (cells, belts, power supplies) | First visit where stock is held; exchange pool otherwise | Downtime scales with the slowest consumable |
The spares clause deserves the most negotiation. A cell wash can take 2-4 weeks in an off-site soak-and-dry cycle; if the system holds no spare cell, the kitchen runs without its purification stage for that period, and odour complaints resume. Negotiate either an exchange pool, where the contractor holds cleaned cells against your serial numbers, or consignment stock on site. Ask each tenderer how many units of your cell type they hold within a day’s travel; the answer predicts service quality better than any brochure.
Records: The Part Your Insurer Actually Reads
Specify the report as a deliverable with contents, or you will receive a one-line invoice and a smile. A complete per-visit report contains: date and time on site; technician name; before-and-after photographs of the canopy plenum, filters and cell; deposit thickness readings with probe locations for duct work; electrical readings at the cell test points, current and voltage, against commissioning-referenced values; filter and fan condition notes; and defects found with the action agreed. The certificate should reference NFPA 96 or TR19 Grease, be sequence-numbered, and be signed. Reports are retained for five years and are yours to forward to the landlord or insurer on request. Insist that each visit, not each year, produces its own certificate; an annual summary cannot answer a surveyor asking about last February.
People, Safety and Subcontracting
Kitchen extraction combines electricity, height, grease and trading pressure, so the contract should say who is allowed on the roof and inside the duct. Require lockout and tagout before anyone opens an ESP access door: the high-voltage section must be proven dead and earthed before hands go in. Roof fans mean working at height with proper access equipment. Duct entry is confined-space work with its own training and supervision rules. The contract should name the lead technician, or require vetting and disclosure of subcontractors, and state that the company carries public liability insurance at a figure you can verify on request. These lines are not bureaucracy; each one exists because an incident was eventually traced to its absence.
The Property Manager and the Shared Riser
Malls, food halls and mixed-use buildings share extraction risers, and the head lease plus service-charge rules decide who pays for what. Your contract must not assume you carry the riser alone. Practical clauses: the riser cleaning schedule annexed to the agreement and cross-checked against other tenants’ visits; access windows agreed around trading hours with noise limits for roof work; landlord permits for roof access obtained by whoever the lease names; reinstatement after works, so disturbed finishes are made good; and a joint deposit-measurement protocol, so every tenant’s certificate derives from readings all parties accept. If you are the only tenant on a shared riser serviced under a proper contract, you are subsidising the others’ fire risk; raise the schedule at the service-charge meeting, not after the incident.
Negotiation Levers That Do Not Cut the Specification
Price concessions that remove work from the schedule cost more than they save, so negotiate on structure instead. A multi-year term can buy a benchmark clause: if a comparable tender comes in lower, the price is re-opened. Secure the right to witness one visit per quarter; watching the cell come out wet and go back in dry tells you more than any KPI dashboard. Ask for a training day for in-house staff covering the weekly filter wash, visual carbon checks, and when to call. Pool consumables on site so a burst seal does not wait for a van. Keep termination for convenience at 60 days. Attach performance credits when response times are missed, and hold an annual specification review where last year’s readings set next year’s scope.
One interface to settle in writing before the first defect: warranty work. The 12-month whole-unit warranty on the equipment is the supplier’s obligation. The service contract should record that the manufacturer or its appointed partner attends warranty items, and that third-party servicing to the manufacturer’s schedule does not void that warranty. Settling this during a breakdown means settling it under pressure.
Red Flags in a Draft Contract
Strike these out, or ask them to be priced openly:
- A single-line invoice for “cleaning” with no task breakdown
- No deposit measurement on duct work, so nobody can prove condition
- No photographic evidence in the report
- Cleaning frequency not tied to cooking duty; one cadence for every client
- Exclusions left unlisted and invoiced ad hoc
- Consumables recharged “at list price” without cost documentation
- No named technician and no subcontractor disclosure
- No per-visit certificate, only an annual summary
- An annual price far below every competitor with unlimited call-outs; that is not generosity, it is scope the contract will reveal later
What This Means for Different System Types
The negotiation logic is identical across architectures; what changes is the service inventory, and that should shape which clauses you weight.
A ductless all-in-one hood keeps nearly everything in one enclosure: the capture canopy, the ESP cell and a carbon odour stage. The service visit is a cell wash, an insulator check, a carbon assessment and a filter clean, done inside the kitchen in one to two hours, with no duct entry and no roof access. That is the appeal of the ductless range hood family Souniny builds for tenants: the certificate is produced per unit, not per riser. Where the load is light (a cafe, a bakery, a steaming-led menu), the N-series carries the same service routine at lower intensity; where the menu fries hard, the ND-series adds treatment capacity but keeps an identical checklist. Pairing the hood with an Odor Removal Tower splits the carbon stage into its own cabinet, which simplifies the swap: tower cartridges change on interval while the cell is away being washed.
Where the building supports a full duct run and volumes are high, the ducted ESP purifier range moves part of the service to the plant side: cells and the centrifugal fan are served in the plant room or at roof level, duct deposit readings enter the report, and access equipment becomes a genuine cost line, so schedule it into the contract rather than discovering it at the first roof visit.
Mobile carts run the simplest routine of all: filter cleaning, surface degreasing and a cell wipe-down, all at bench height. For market pitches and event catering, the ventless catering cart line is servable by one trained person in under an hour, and the same reporting discipline still applies.
A One-Page Checklist Before You Sign
Condense the negotiation into twelve lines and take them into the meeting:
1. Scope: the nine line items written down; exclusions priced as options. 2. Frequency tied to cooking duty, never a single annual clean. 3. Cell wash interval stated for your duty: 2-4 weeks on heavy loads. 4. Carbon assessed at every visit and replaced on a 3-6 month interval. 5. Response times set: 24 hours for safety events, 48 hours for odour complaints, a fixed calendar for planned visits. 6. Spares named: exchange pool or consignment stock for cells, belts and power supplies. 7. Report contents specified: photographs, deposit readings, electrical readings. 8. A certificate per visit referencing NFPA 96 or TR19 Grease. 9. Consumables at documented cost with capped handling; parts cost-plus with a cap. 10. Price fixed 12 months, then a named index capped at 3-5% with 60 days notice. 11. The warranty interface in writing: the supplier attends warranty items, and scheduled third-party servicing does not void cover. 12. Termination for convenience at 60 days and the right to witness a visit each quarter.
Sign the contract that produces evidence. The equipment choice decides how often someone must open the cell door; the contract decides whether, when a surveyor or an adjuster asks, the answer arrives as a folder of dated certificates or as an argument.
