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Why is a polypropylene heater casing more durable than a metal one in industrial environments? Steel or EPP?
January 27, 2026
Table of contents
Many investors and installers, when they first see a unit heater with a polymer casing, ask the same question: “Will this really withstand industrial conditions?” For years, we have been accustomed to treating steel as a synonym for durability. Galvanised, powder-coated sheet metal appears solid, robust and safe.
However, modern industrial heating has undergone a significant shift. EPP (expanded polypropylene) — often incorrectly confused with polystyrene — is increasingly replacing steel on the market. And this is not a cost-driven decision, but one based on purely technical reasons. In this article, we explain why engineers are choosing EPP more and more often, and why in this case “plastic” actually means a longer service life for the device
Key information
- EPP is not polystyrene: It is a flexible structural material used, among others, in automotive bumpers to absorb impact energy.
- Shape memory: An EPP casing does not suffer permanent dents — after impact, it returns to its original form.
- Chemical shield: The material is fully resistant to corrosion, ammonia and moisture, making it ideal for agricultural and industrial applications.
- Acoustics: An EPP housing dampens vibrations, resulting in quieter operation.
- Installer benefit: The unit is up to 30% lighter than a comparable steel version
What is EPP and why is confusing it with polystyrene a mistake?
Let’s start with the definition. EPP is expanded polypropylene. Unlike polystyrene (EPS), which is brittle and prone to cracking, EPP combines high mechanical strength with low density.
The best proof of EPP’s durability is its widespread use in the automotive industry — it is used to manufacture car bumpers and impact energy-absorbing components. If this material is capable of protecting a driver during a collision, it will have no difficulty protecting a heat exchanger in a warehouse or industrial hall.
EPP housing vs steel – how do they behave under mechanical impact?
Every unit heater installed in a workshop is exposed to various types of accidental damage — for example, being hit by a ladder, a pipe, or other equipment during daily operation.
A steel casing has a defined yield point. Once this limit is exceeded, the sheet metal undergoes permanent deformation, resulting in dents. Worse still, the impact often damages the paint coating (even with powder coating). This creates a risk of electrochemical corrosion, especially in humid industrial environments.
An EPP housing, on the other hand, features so-called “shape memory”. It is a viscoelastic material. Upon impact, its cellular structure flexes and absorbs the energy, then returns to its original shape. There are no dents, no chips, and no corrosion.
For the investor, this means that after five years of operation, the unit looks the same as on the day of installation, rather than resembling a battered metal casing.
Why should a workshop unit heater be lightweight and quiet?
The durability of EPP is not its only advantage. Steel is a rigid material that transmits vibrations very effectively. A fan operating inside a steel housing often causes the casing to resonate, generating a characteristic “humming” noise that can be tiring for workers.
By nature, EPP acts as an acoustic insulator. Its cellular structure dampens motor vibrations and airflow noise. As a result, HC series units are noticeably quieter than steel-cased alternatives with the same performance parameters.
The second key aspect is weight. EPP is lightweight, which significantly simplifies installation.
What benefits does an EPP housing offer?
| Parameter | Steel housing (painted) | EPP housing (Reventon HC) |
| Corrosion resistance | Medium (depends on coating quality and surface damage) | Total (the material does not corrode) |
| Impact response | Permanent dents, prone to scratching | Returns to original shape (elasticity) |
| Thermal insulation | None (metal conducts heat) | High (no heat loss through the casing) |
| Unit weight | High (difficult installation) | Low (easy installation) |
| Acoustics | Risk of housing resonance | Vibration damping (quiet operation) |
Benefit for the CONTRACTOR / INSTALLER
You save both time and physical effort. Due to the relatively high weight and size of steel-cased unit heaters, installation typically requires at least two people. An EPP-cased heater, however, can be up to 30% lighter, which may allow installation without the need to hire lifting equipment.
The 360° mounting bracket, supplied as standard, allows the installation to be completed within minutes.
Benefit for the INVESTOR
You buy once and buy right. The unit is resistant to mechanical damage and more cost-effective compared to a steel equivalent. The lower weight also means reduced load on the roof structure, which is particularly important when refurbishing or adapting older buildings.
Summary
By choosing a unit heater with an EPP housing, you gain a device that is lighter, quieter, and above all fully resistant to corrosion and mechanical damage.
The strongest confirmation of this material’s quality is the warranty itself. We offer a lifetime warranty on EPP housings in our units. This is a clear statement that, as a manufacturer, we are fully confident in the durability of this solution — even after many years of operation in demanding industrial conditions.
FAQ – Technical questions about EPP
1. Is EPP safe for use in a welding workshop? Is it flammable?
The EPP used in Reventon unit heaters is a material that does not sustain combustion. Naturally, direct contact with an open flame will cause the material to melt, but under standard workshop conditions it is a safe and proven solution.
2. Does an EPP casing degrade due to UV exposure or ageing over time?
No. EPP is resistant to ageing. Unlike low-quality plastics, it does not chalk, become brittle or crack as a result of prolonged exposure to sunlight.
3. How should an EPP casing be cleaned? Can a pressure washer be used?
High-pressure washers should not be used directly on the casing. That said, EPP is resistant to water and most chemicals (including oils, greases and solvents). It can be cleaned using compressed air or a damp cloth.
In the case of heavy soiling, the casing’s moisture resistance allows for washing with low-pressure water — without the risk of corrosion that typically affects steel housings.
Do you have questions about selecting the right unit heater for your building volume?
Our technical team is here to calculate, not to guess. Send us the layout of your facility and we will select devices that deliver reliable heating without blowing your budget.
