FAQ

Straight answers about HLN Aerolyn air heaters and Aquano coolant heaters — with independent test results and verifiable certification numbers wherever possible.

1. Is the HLN Aerolyn as good as a Webasto or Espar heater?

In an independent comparison by Boreal Camper (Canada) covering diesel heaters from $100 to $2,000, the HLN Aerolyn performed at the same level as Webasto and Espar and clearly outperformed budget and mid-range heaters. For hydronic heaters, Ovens Garage (US) put the Aquano 5K head-to-head with Webasto's Thermo Top Evo: both excellent, with the HLN delivering slightly more heat at a considerably lower price. HLN has been a genuine OEM supplier to Fortune 500 truck makers for 50 years — you get the same factory-grade heater for 30–50% less. Watch every original test on our Independent Reviews & Tests page.

2. What does E-mark / ECE R122 certification mean?

ECE R122 is the United Nations vehicle regulation for combustion heaters. An E-mark type approval means an independent, government-designated laboratory tested and approved the heater design — most budget diesel heaters carry no such approval. HLN heaters are approved by SNCH (Luxembourg):

Aerolyn 2000/4000 PRO (2/4kW air): ECE R122 approval no. E13*122R00/06*0310*00; ECE R10 (EMC) approval no. E13*10R06/01*16437*00.
Aquano 5K (5kW coolant): ECE R122 approval no. E13*122R00/06*0247*01; ECE R10 approval no. E13*10R06/01*15774*01.
Aquano 10K (10kW coolant): ECE R122 approval no. E13*122R00/04*0143*01; ECE R10 approval no. E13*10R05/01*14202*01.

All numbers are verifiable in the UNECE type-approval database.

3. How is HLN different from cheap Amazon diesel heaters?

Independent teardowns by David McLuckie (UK) found: a finely machined brushless fan motor rated for 5,000+ hours (roughly 2.5× the life of the brushed motors in budget heaters), a high-performance alloy combustion chamber (magnet-verified, noticeably heavier than cheap units), a glass-reinforced (GRP) housing, waterproof ECU and harness connectors, and an integrated muffled intake/exhaust. Van Life UK rated the Aerolyn above Lavaner's entire range including the Pro Max; Ryan Fox (US) reached the same conclusion against typical Amazon bunk heaters.

4. Why do diesel heaters smoke and soot up at altitude — and what does altitude compensation do?

At altitude the air is thinner: the heater injects the same fuel but gets less oxygen, so the mixture runs rich — causing white smoke, soot and carbon buildup. HLN Aerolyn heaters compensate automatically by adjusting the fuel/air ratio: up to 3,000 m / 10,000 ft on the 2kW, and up to 5,000 m / 16,000 ft on the 4kW and other models. No manual high-altitude kit needed.

5. Should I get the 2kW or the 4kW?

Rule of thumb: 2kW for vans, campervans and boats; 4kW for semi-truck bunks, large vans, buses and workshops. A smaller heater working steadily burns cleaner than a big heater idling at its lowest setting (which builds carbon). See the sizing comparison by Hangin with the Hursts (US) on our Reviews page.

6. Air heater (Aerolyn) or coolant heater (Aquano) — which do I need?

An Aerolyn air heater blows hot air directly into the cabin — the choice for living-space comfort. An Aquano coolant (hydronic) heater heats the engine coolant loop: it preheats the engine for cold starts, defrosts the windshield, and can supply domestic hot water through a heat exchanger. Many trucks and expedition vehicles run both.

7. What is included in the installation kit?

Every HLN heater ships with a complete installation kit: quiet fuel pump (ranked second-quietest of six pumps tested by Defender Canada — behind only Espar's newest S3), fuel line and pickup, integrated muffled intake/exhaust system, mounting hardware, wiring harness with protective loom built to truck-installation standards, and the controller (WiFi or Bluetooth depending on model).

8. What does the 2-year warranty cover?

HLN warrants its heaters and heater kits against defects in material and workmanship for two (2) years from the date of installation (or vehicle registration date for original-equipment installations), up to a maximum of three (3) years from HLN's original date of sale. Products must be installed, operated and maintained according to HLN's written instructions. The warranty covers the product itself, not the installation. Not covered: faults from incorrect installation, maintenance or voltage; external damage, accidents or moisture; unauthorized repairs; transport damage; units with illegible or missing serial numbers; and consequential costs. Keep your purchase receipt — it is required for warranty claims.