A diesel generator needs four things from its installation: an outdoor or well-ventilated location, free cooling airflow, an exhaust path that carries fumes away from people, and a level, rigid base. Get those four right and a correctly sized set will run for years. Get any of them wrong and you will see overheating, shutdowns or a real safety hazard, however good the machine is.
This guide covers the decisions in the order you will face them. It applies to open-frame and silent (enclosed) diesel generators in the small and medium power classes used on farms, work sites, shops and small industrial sites.
Step 1: Choose the location
The location limits every later decision.
- Never install indoors without engineered ventilation. Engine exhaust contains carbon monoxide, which is colourless, odourless and deadly in enclosed spaces. A garage with the door open is not ventilation.
- Prefer a dedicated outdoor spot or a shelter with open sides: a roof against rain, and free air movement on all sides.
- Keep the unit away from the windows, doors and air intakes of occupied buildings, and place it so the prevailing wind carries exhaust away from them.
- As a working rule, leave about one metre of clear space on every side for cooling air, refuelling and maintenance access. Check your unit’s manual; silent units state their own minimum clearances.
- Think about noise direction when you choose the site. Even a silent unit under 75 dB is easier to live with when its exhaust side faces away from work and living areas. If noise decides your choice between open-frame and enclosed, see our guide on how quiet a silent diesel generator is.
Step 2: Ventilation, the airflow nobody calculates
A diesel engine uses air twice: for combustion and, in far greater volume, for cooling. The radiator or cooling fan must draw fresh air in on one side and push hot air out on the other, without the two streams mixing.
| Installation mistake | What it causes |
|---|---|
| Set pushed into a corner, radiator facing the wall | Hot air recirculates → coolant temperature rises → thermal shutdown on hot days |
| Enclosure or shed with intake and outlet on the same side | The same recirculation, hidden inside a box |
| Tarp or cover over a running unit “against dust” | Blocked airflow and overheating within minutes |
| Unit at altitude sized without margin | Thin air cools and burns fuel less well; see how altitude derates diesel power |
The working rule: cooling air enters low on one side, hot air leaves high on the opposite side, and the outlet never blows toward the intake.
Step 3: Exhaust, routed away from people
- Point the exhaust outlet away from buildings and downwind, and never toward a walkway.
- If you extend the exhaust with pipe, keep the run short, with few bends. Every bend adds back-pressure, which costs power and raises exhaust temperature. Long runs need a larger pipe diameter; follow the limits in the engine manual.
- Fit a flexible section between the engine and any fixed pipe, so vibration does not crack the manifold.
- Finish the pipe with a rain cap or a 45° downward cut, so water cannot enter a stopped engine.
Step 4: Foundation and vibration
- A small generator set needs a level, rigid surface. A concrete pad is ideal; compacted gravel with a paver base works for portable units.
- Keep the unit level to within a few degrees. A diesel engine lubricates correctly, and its fuel gauge reads correctly, only when it stands close to horizontal.
- Anti-vibration mounts between the frame and the pad stop vibration from spreading into structures and loosening fittings over time.
- Raise the pad slightly above ground level so rainwater and washdown water drain away from the unit.
Step 5: Electrical work, earthing and the changeover switch
- Earth the unit according to your local electrical code, usually with a dedicated earth rod bonded to the generator’s earth terminal. Local code always takes priority over general advice.
- If the generator backs up a building supply, install a transfer switch (manual or automatic), so the generator and the grid can never feed the same circuit at once. Backfeeding through a wall socket is illegal almost everywhere and endangers line workers.
- Size the cables for the full rated current and the length of the run. Undersized cables run hot and lose voltage. If you have not yet settled the generator size itself, start with how to size a diesel generator.
First-start checklist
- Engine oil and coolant at the correct levels (unit level when you check)
- Fuel fresh and clean; water separator drained
- Clearances respected; nothing stored against the unit
- Exhaust route clear and pointing away from openings
- Earth connection made; transfer switch in the correct position
- First run at light load for the running-in period the manual specifies
Have the installation checked against your site
Every site adds its own conditions, such as altitude, dust, coastal air or mounting in a container. Browse our diesel generator range, then send us your site conditions and load list, or message us on WhatsApp. Our engineers will confirm the right configuration and the installation points that matter for your site within 24 business hours.