Short answer: An ESP is normally positioned downstream of effective canopy grease separation and upstream of sensitive gaseous-treatment stages such as activated carbon. Its exact location must also provide suitable airflow distribution, safe cell withdrawal, structural support, electrical access and a practical cleaning route.
The theoretically correct treatment order can still fail if the unit is squeezed above a ceiling with no service space, placed after a source of water carry-over, exposed to unsuitable temperatures or connected immediately after a turbulent bend against manufacturer instructions. Position is therefore a design, access and maintenance decision—not a spare-space decision.
Important: This guide explains design questions; it is not a product selection, planning approval or performance guarantee. A competent designer should assess the actual kitchen, air system, discharge and maintenance conditions.
Position within the treatment sequence
Larger grease droplets should be removed at the canopy before the air reaches the ESP. The ESP can then reduce finer particulate loading before carbon or other downstream odour stages. Fans, attenuators and UV equipment must be ordered according to the selected manufacturer’s requirements and the project fire, access and noise strategy.
- Canopy grease separation first.
- ESP placed where its inlet conditions are acceptable.
- Gaseous odour treatment protected from grease where practicable.
- Discharge and fan arrangement coordinated with the complete design.
Space and safe cell removal
Collector cells can be large, heavy and contaminated. The access door needs a clear withdrawal zone at full cell depth, plus safe footing, lighting and a route to the cleaning area. A hatch below the unit is not automatically adequate if the cell cannot be handled without working over equipment or a ceiling void.
- Measure the full withdrawal distance.
- Check lifting and manual-handling needs.
- Provide a safe working platform where required.
- Keep access away from hot surfaces and live kitchen production.
Duct geometry and environmental conditions
The manufacturer may specify straight lengths, transition angles, temperature limits, orientation and drainage provisions. Poor transitions can create uneven velocity across the cell bank. Condensation, washing water or grease leakage must not reach electrical components or unprotected building fabric.
- Follow manufacturer inlet and outlet geometry.
- Support the casing independently as required.
- Coordinate drains or drip management where specified.
- Seal access and duct joints against leakage.
What the observation may be telling you
| Observation | What it may mean | Correct next step |
|---|---|---|
| Immediately after a sharp bend | Uneven velocity may load part of the cell bank | Add an appropriate transition or straight section |
| Above a fixed ceiling with no hatch | Cells cannot be removed for cleaning | Redesign access and ceiling coordination |
| Before effective grease separation | Rapid contamination and fire/maintenance burden | Improve upstream capture and filters |
| Ahead of carbon with good pre-filtration | Common treatment-train position | Verify product-specific requirements |
| External or rooftop position | Weather, corrosion and access risks | Provide suitable enclosure, supports and safe access |
A practical design and handover workflow
Treat the filtration unit as one component of an air system. A dependable design starts with the cooking process and ends with a maintainable discharge, rather than starting with a catalogue airflow. The following workflow gives the client, designer and installer a shared audit trail.
- Define the source. List every appliance, fuel, cooking method, duty, diversity assumption and operating period. Chargrilling, frying and light reheating do not create the same grease, smoke or odour load. Record the future menu where the tenant is not yet trading.
- Establish the air duty. Calculate the extract volume and capture arrangement, then record the expected operating range. Check make-up air, duct velocity, leakage class, fan curve and the resistance of clean and loaded treatment stages.
- Select the treatment train. State what each stage is intended to remove, the evidence used for selection and the conditions attached to any performance claim. Include bypass sealing, controls, interlocks, alarms and the effect of failure.
- Prove and maintain it. Commission airflow and functions at the installed condition. Give the operator baseline readings, access instructions, cleaning intervals, consumables and a clear trigger for inspection or replacement.
Keep a useful record: Keep the approved drawing, design airflow, fan duty, clean pressure readings, control cause-and-effect, commissioning results and maintenance log together. When performance changes, comparison with this baseline is more useful than replacing parts by guesswork.
Project or service checks
- Mark the unit and withdrawal zone on coordinated drawings.
- Confirm the treatment sequence with the system designer.
- Obtain manufacturer requirements for orientation and straight duct.
- Check casing weight, supports and lifting route.
- Coordinate electrical isolation and controls access.
- Plan how dirty cells move to and from the cleaning location.
- Photograph and record final access before ceilings are closed.
Turn the agreed checks into named deliverables. Each item should have an owner, due date and acceptance method. Where a measurement is required, record the value, unit, instrument or source, operating condition and result. This makes the information usable at handover and during a later investigation.
Common mistakes to avoid
- Showing only the casing footprint and not the service envelope.
- Locating electrical access against a wall.
- Assuming any ceiling hatch allows cell withdrawal.
- Ignoring weather protection for external installations.
- Using flexible connections or transitions that distort the inlet flow.
Avoid closing the issue on appearance alone. A new filter, reset controller or revised drawing may change the symptom without resolving the underlying duty, utility, access or maintenance problem. Confirm the completed work under a representative operating condition and keep the evidence with the asset or ventilation record.
Frequently asked questions
Can an ESP be installed vertically?
Only where the selected product and manufacturer permit that orientation. Drainage, cell support and access may change.
Should the fan be before or after the ESP?
Both arrangements exist. The designer should follow product requirements and consider leakage, pressure regime, access, noise and downstream equipment.
Can the ESP go outdoors?
Potentially, if the equipment is suitable and weather protection, corrosion, structural support, isolation and safe access are designed.
Related Kitchen Install Guide reading
- Best Route for Commercial Kitchen Extract Ductwork
- Where Do Kitchen Extract Cleaning Access Panels Need to Go?
- What Should a Kitchen Extraction Quote Include?
Capture the installation and commissioning detail
Use the KIG 318 Commercial Kitchen Installation Checklist to record interfaces, checks, outstanding actions and the evidence needed at handover.
Sources and further guidance
- BESA: DW/172 Specification for Kitchen Ventilation Systems
- Purified Air: Commercial kitchen ESP systems
- Extechnology: Duct design and ESP performance
- HSE: Ventilation of kitchens and catering establishments
Last reviewed: 14 August 2026. This article provides general commercial-kitchen design information. It does not replace a site-specific ventilation design, manufacturer instructions, risk assessment, planning conditions or advice from a competent specialist.