---
title: Lepido – The World’s Most Resilient Heat Exchanger
description: "When developing Lepido, we had a clear goal: to create the world’s most resilient heat exchanger – a solution that can handle dirty exhaust air without pre-filters, without extensive cleaning, and without operational disruptions."
image: https://content.enjaysystems.com/hubfs/Canva%20images/Canva%20Design%20DAGcWR3dMX8.png
---

 Article // 26.3.2025

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## Lepido – The World’s Most Resilient Heat Exchanger

When developing Lepido, we had a clear goal: to create the world’s most resilient heat exchanger – a solution that can handle dirty exhaust air without pre-filters, without extensive cleaning, and without operational disruptions.

![lepido-1](https://content.enjaysystems.com/hs-fs/hubfs/lepido-1.png?width=1093&height=645&name=lepido-1.png)

But words alone aren’t enough. It needs proof.

That’s why we subjected Lepido to a long-term test in one of the most challenging ventilation environments imaginable: the exhaust duct of a commercial kitchen – specifically, a Burger King restaurant in Malmö, Sweden. Open-flame grilling creates an air stream filled with grease, particles, moisture, heat, and dirt.

![image-png-4](https://content.enjaysystems.com/hs-fs/hubfs/image-png-4.png?width=944&height=371&name=image-png-4.png)

Photo from the ventilation system of a fast food restaurant (not Burger King)

**If Lepido can handle this – it can handle anything.**

**The Challenge: Where other systems fail**  
Dirty exhaust air is the enemy of ventilation systems. Grease, soot, lint, and dust clog conventional heat exchangers, causing high pressure drops, costly maintenance, and eventually – total system failure.

In many operations, heat recovery is therefore avoided altogether because the maintenance costs outweigh the energy savings.

**The Solution: A new type of heat exchanger**  
Lepido is unlike any other heat exchanger. Instead of dense fins, we use a patented geometry with open coils and a large free area – specifically designed to withstand dirty airflows. The construction is made for direct duct installation, with no need for filters.

## **Behind the design:**

**Patented coil geometry with high free area**

**100% counterflow operation**

**Multiple liquid channels**

**Designed to match the heat transfer performance of conventional systems – but without their vulnerabilities**

 

### **![image-png-Jan-16-2025-10-16-44-7019-AM](https://content.enjaysystems.com/hs-fs/hubfs/image-png-Jan-16-2025-10-16-44-7019-AM.png?width=909&height=470&name=image-png-Jan-16-2025-10-16-44-7019-AM.png)**

### **Test Environment: A kitchen filled with grease, smoke, and heat**

In autumn 2020, Lepido was installed in the exhaust duct of Burger King Malmö – a location where hot, dirty air containing grease and particles flows 16 hours a day. A real-world test, with no compromises:

**No pre-filter**

**No maintenance or cleaning of the Lepido**

**Operation: 22 months continuously**

**Kitchen airflow: 1020 l/s, average temperature 34°C**

**System performance was monitored every minute via a central control system**

 

### **![MicrosoftTeams-image](https://content.enjaysystems.com/hs-fs/hubfs/MicrosoftTeams-image.png?width=712&height=333&name=MicrosoftTeams-image.png)**

Photo from the ventilation system of a fast food restaurant (not Burger King)

### **The Results: Proof of extreme durability**

After 22 months of continuous operation, the results are clear:

**Operational disruptions: 0**

**Pressure drop increase: Only about 50 Pa (equivalent to 25 Pa/year)**

**Efficiency loss: Just -1% in thermal effectiveness**

**Energy recovered: approx. 86,000 kWh/year**

Yes – there is some buildup on the coils (see image). **But the impact on performance is negligible, and the system has delivered stable and efficient heat recovery without a single interruption.**

![20220706_104430-min (1) (2)](https://content.enjaysystems.com/hs-fs/hubfs/20220706_104430-min%20(1)%20(2).jpg?width=9248&height=6936&name=20220706_104430-min%20(1)%20(2).jpg)

Image of the Lepiod after 22 months in operation with no cleaning

### **Conclusion: A new level of robustness in energy technology**

We set up the test to prove that Lepido can do what no other heat exchanger can. And the results speak for themselves:

**Lepido is demonstrably built to withstand the harshest environments – without compromise.**

This opens the door to profitable and trouble-free energy recovery in:

**Commercial kitchens**

**Drying facilities**

**Foundries**

**Food processing plants**

**Industrial laundries**

**Wood and biomass industries**

**Any environment where dirty exhaust air has previously been a barrier**

**Want to learn more or have a project with dirty exhaust air?**  
Get in touch – we’ll assist with everything from calculations to project planning.