Choose a fanless vision computer enclosure from the complete installed heat load, the hottest local ambient, and the computer manufacturer's thermal limits. A 40 W processor setting does not establish the enclosure cooling requirement. At 104–113°F [40–45°C] ambient, passive cooling needs a verified path from the computer to the surrounding air.
If that path cannot maintain the required temperatures during continuous operation, change the enclosure, cooling method, or installation location. Specify the enclosure and computer as one thermal assembly, then validate the actual camera-processing and recording workload before repeating the build.
Define the environment at the enclosure
Use the air temperature where the enclosure will operate, not a regional weather average or an air-conditioned room rating. Measure near the proposed installation during the hottest operating period. Include heat from nearby equipment, restricted spaces, and any direct sunlight.
An enclosure beneath a counter may receive warmer air than the occupied room. Stored materials can block its cooling surfaces. A cabinet beside a refrigeration condenser can experience hot discharge air even when the room feels comfortable.
Record these conditions before choosing the shell:
- Maximum local ambient temperature during continuous operation.
- Minimum temperature during shutdown, transport, and overnight storage.
- Indoor, sheltered outdoor, or exposed outdoor installation.
- Dust, cleaning spray, salt, humidity, and cleaning chemicals.
- Available clearance around the proposed heat-rejection surfaces.
- Whether fans are prohibited throughout the installation or only inside the computer.
For sun-exposed installations, separate ambient temperature from radiant heating. The article on outdoor enclosure heat gain explains why a shaded air measurement does not capture every load.
High humidity also matters when cooling equipment can create cold surfaces. A sealed enclosure does not automatically prevent condensation from trapped moisture or humid air entering through cable routes.
Choose the environmental rating separately
Choose the enclosure type for the actual exposure, then solve cooling within that boundary. A cooling accessory must not quietly undermine the protection you selected.
A clean, dry indoor location may need only NEMA Type 1 protection. Indoor dust and dripping liquids can point toward Type 12. Hose-directed cleaning calls for Type 4 protection, while corrosive exposure can justify Type 4X.
For our custom enclosures, NEMA types are manufacturer ratings for the specified design; the enclosures are not UL listed. Establish any project listing requirement before ordering. The article on US enclosure design requirements covers that separate specification decision.
Do not select a washdown rating merely because the computer operates in a humid climate. Conversely, a dry operating room does not justify an open vent when cleaning spray can reach the installation.
Specify the required protection for the completed assembly, including cooling penetrations, cable entries, doors, and unused openings. Filtered ventilation exchanges internal and external air. It is not equivalent to a sealed cooling arrangement.
Select material for corrosion and the thermal path
We build custom enclosures in 304 stainless steel, 316L stainless steel, powder-coated carbon steel, aluminum, and specified nonmetallic materials. Choose material for the installation environment before treating it as part of the cooling system.
304 stainless suits many indoor and general outdoor applications. Consider 316L where salt air, brine, or chloride exposure requires greater corrosion resistance. Powder-coated carbon steel can suit sheltered industrial installations where coating damage and corrosion exposure are controlled.
Aluminum conducts heat more readily than stainless steel. However, material alone does not establish cooling capacity. Contact area, wall thickness, external surface area, orientation, and airflow all affect the result.
A stainless shell can protect equipment while a separate engineered thermal path carries heat to an external sink. That interface needs structural support and a sealing design. Do not assume that attaching a computer to a backplate creates effective conduction through the enclosure wall.
Define mounting contact surfaces, interface materials, fastening requirements, and external sink clearances with the computer's thermal requirements. Any dissimilar-metal interface also needs corrosion review for the actual moisture exposure.
Calculate the complete load and usable size
Establish the electrical and thermal boundary before adding component values. Processor power, complete-computer input, and power-supply input are different measurements. Adding all three can count the same heat more than once.
For an illustrative estimate, assume these separate internal heat sources:
| Internal item | Assumed dissipation | Basis to replace before approval |
|---|---|---|
| Compute module | 40 W | Maximum sustained dissipation for the configured workload |
| Carrier electronics | 10 W | Losses excluding the module and separately counted loads |
| Storage | 6 W | Sustained recording operation |
| Network electronics | 8 W | Internal electronics, excluding power delivered outside |
| DC load subtotal | 64 W | Sum of the nonoverlapping loads above |
| Internal power-supply loss | 7.1 W | 64 W output at an assumed 90% efficiency |
| Enclosure heat total | About 71 W | Excludes sunlight and nearby radiant sources |
These are calculation assumptions, not computer specifications or enclosure performance claims. Replace them with documented maximum losses or measurements from the intended assembly.
For the example supply, input power is 64 W divided by 0.90, or approximately 71.1 W. The difference becomes supply heat. If that supply sits outside the enclosure, its losses do not belong inside this thermal boundary.
Likewise, power delivered to external cameras is not automatically enclosure heat. Count internal conversion and switching losses, not the entire exported electrical load. Use the enclosure heat calculation guide for the underlying calculation method.
Size the enclosure around equipment, connectors, cable bends, cooling hardware, and service access. Reserve space for the complete thermal solution before approving outside dimensions. A larger box may help passive dissipation, but empty volume alone does not guarantee a safe operating temperature.
Match cooling to the available temperature difference
Obtain the computer's permitted inlet, case, or thermal-interface temperature for the chosen configuration. Also obtain limits for storage, power conversion, networking, and any backup power equipment. Use the relevant limit at each measurement location.
Suppose a component requires internal air no warmer than 140°F [60°C], while local ambient reaches 113°F [45°C]. The available internal-air rise is only 27°F [15°C]. For the illustrative 71 W load, the complete passive enclosure would need an effective air-to-ambient thermal resistance no higher than approximately 0.21°C/W.
That is a screening requirement, not proof that a particular enclosure will work. It excludes additional heat gain and leaves no allowance for uncertainty. A conducted computer heat path also requires separate checking against its specified case or interface limit.
Choose the cooling approach according to that available temperature difference:
| Approach | Appropriate starting condition | What must be demonstrated |
|---|---|---|
| Passive sealed shell | Ambient remains below allowable equipment temperatures | Complete heat rejection at the worst mounting condition |
| Conducted path to an external sink | Computer provides a defined thermal interface | Interface contact, spreading, sink performance, and sealing |
| Closed-loop air-to-air heat exchanger | Outside air stays below the required internal air temperature | Adequate capacity at the actual temperature difference |
| Refrigerated enclosure cooling | Passive methods cannot meet the required internal temperature | Net cooling capacity at maximum ambient and required setpoint |
An air-to-air heat exchanger cannot maintain internal air below ambient. A cooling unit's headline capacity also may not apply at your hottest ambient. Require performance data at the proposed operating conditions, including losses introduced by the cooling equipment.
The article on cooling below ambient in an enclosure explains when refrigeration becomes necessary and why moisture control must follow.
Keep the meaning of fanless explicit. A fanless computer installed in a fan-cooled cabinet is not a completely fanless installation. If all fans are prohibited, passive performance must be demonstrated; otherwise relocate the equipment or revise the requirement.
Preserve cooling when mounting and sealing
Install the enclosure in the orientation used for thermal qualification. Natural-convection fins need their specified clearance and airflow direction. A nearby wall, cable bundle, or counter panel can obstruct them.
Use the computer manufacturer's mounting method for any chassis thermal interface. Do not substitute a convenient bracket where a flat, controlled contact surface is required. Avoid transferring unsupported loads through cooling joints or cable connectors.
Specify cable entries away from gasket lands and cooling interfaces. Include cable diameters, connector envelopes, bend requirements, and access for tightening each gland. Seal unused openings with suitable fittings rather than leaving future cable holes uncovered.
Provide the required protective bonding for conductive parts. Review whether removable doors, external sinks, or cooling assemblies need dedicated bonding connections. Thermal interface compounds and mechanical hinges should not be assumed to provide the required electrical path.
For a build that combines several equipment sections, the machine control cabinet specification helps coordinate mounting, entries, and assembly requirements before fabrication.
Validate the production assembly under sustained load
Set acceptance criteria before approving a pilot. The test must represent the intended computer, enclosure, mounting arrangement, and cooling method. An open-bench result does not qualify a sealed installation.
Run the actual continuous workload, including four camera streams if that is the deployment requirement. Include decoding, inference, evidence recording, network traffic, and any other sustained services. A processor-only stress test may miss storage heating or a different power distribution.
Measure local ambient, relevant internal air temperatures, and manufacturer-defined case or interface temperatures. Log component telemetry, processing throughput, recording performance, and thermal throttling indicators. Continue until temperatures stabilize and operation remains representative of continuous service.
Document acceptance against:
- Every component's specified operating temperature limits.
- Required sustained processing and recording performance.
- Any unacceptable thermal throttling or thermal shutdown.
- Cooling controller behavior and restart after a permitted power interruption.
- Condensation risk during cooldown and changing humidity.
- Maintenance conditions, including any specified filter or heat-sink contamination allowance.
Use controlled test conditions and applicable electrical safety procedures. Power-quality protection is a separate requirement; an enclosure cannot correct supply fluctuations by itself. Include the losses and space of any installed protective or backup equipment in the design.
Retest when the power mode, carrier, storage, cooling interface, enclosure mounting, or processing workload changes materially. The enclosure selector can narrow dimensional and environmental choices, but a dimensional match does not establish thermal suitability.
Put the thermal requirements on the order
Send a defined thermal requirement with the mechanical drawing, not simply a request for a fanless box. For custom enclosures, you define material, width, height, depth, and every cutout, from one piece.
| Order item | Requirement to document |
|---|---|
| Installation environment | Maximum local ambient, minimum temperature, humidity, sunlight, cleaning, and corrosion exposure |
| Enclosure protection | Required manufacturer-rated NEMA type and any separate project listing requirement |
| Material | Selected grade or material, finish, and corrosion considerations |
| Dimensions | Outside width, height, depth, usable mounting space, and connector clearance, in inches with millimetres where needed |
| Installed heat | Maximum continuous internal dissipation, calculation boundary, and supporting measurements |
| Temperature limits | Required air, case, and thermal-interface limits with their measurement locations |
| Cooling arrangement | Passive shell, conduction interface, heat exchanger, or refrigerated cooling, with responsibility clearly assigned |
| Mechanical interfaces | Mounting orientation, contact surfaces, fasteners, supported loads, and external clearances |
| Openings and sealing | Dimensioned cutouts, cable entries, gasket interfaces, and unused-opening treatment |
| Validation | Workload, ambient conditions, temperature logging, performance limits, and required records |
State who supplies, installs, and qualifies each cooling component. Do not assume that a custom shell quote includes computer integration or thermal validation unless those responsibilities are expressly agreed.
For custom work, the approved drawing establishes the build configuration. Resolve thermal interfaces, cooling cutouts, mounting clearances, and acceptance requirements before approving that drawing.
Enclosures for this job
Catalog sizes that suit the job this article answers, picked from its subject; open one for its full specifications.
| Enclosure | Material | Outside H x W x D / display | Rating |
|---|---|---|---|
| 16 × 12 × 8 in | 304 stainless | 16 x 12 x 8 in | Rated NEMA 4X / IP66 by the manufacturer; not UL listed |
| 24 × 20 × 8 in | 304 stainless | 24 x 20 x 8 in | Rated NEMA 4X / IP66 by the manufacturer; not UL listed |
| 30 × 24 × 10 in | 304 stainless | 30 x 24 x 10 in | Rated NEMA 4X / IP66 by the manufacturer; not UL listed |
Questions
Does a 40 W computer power mode prove that a fanless enclosure will work?
No. A processor power setting does not include every carrier, storage, networking, and power-conversion loss. The complete assembly also needs a verified thermal path at the hottest local ambient. Confirm the computer's permitted temperatures and validate sustained operation inside the proposed enclosure.
Can passive enclosure cooling work at 113°F [45°C] ambient?
It can be suitable only when the complete assembly meets its temperature and performance limits at that ambient. The available temperature difference may be small, particularly for internal power supplies and storage. Use documented thermal interfaces and test the intended workload until temperatures stabilize.
Should external camera power be included in the enclosure heat load?
Count losses from equipment physically inside the enclosure. Power delivered to cameras outside the enclosure generally leaves the thermal boundary. Internal network electronics, switching losses, and power-supply inefficiency still contribute heat. Avoid counting exported camera power as though it all becomes internal heat.
When is refrigerated cooling needed instead of a heat exchanger?
An air-to-air heat exchanger transfers heat toward cooler outside air and cannot maintain internal air below ambient. Refrigerated cooling can be necessary when the required internal temperature is too close to ambient or below it. Select capacity at the actual operating conditions and address condensation.
What thermal information belongs in a custom enclosure quote request?
Send maximum local ambient, complete internal heat dissipation, component temperature limits, mounting orientation, and required environmental protection. Include dimensions, cutouts, cable entries, and the proposed cooling interface. Define responsibility for cooling hardware, integration, and validation before approving the enclosure drawing.
