The Espar Airtronic M3 D4L is the better diesel heater overall, rated 3.4 to 2.9. The Espar Airtronic M3 D4L leads on type approval. The TJHSM 5kW Diesel Heater costs $1,591.72 less ($83.28 vs $1,675).
For larger vans, trucks and boats that need a type-approved 4 kW heater that works anywhere, including high mountain passes. It costs far more than clones but is built for years of daily use.
Amazon $1,675A low cost 5 kW split kit for DIY truck and RV installs, sold with almost no published specs or warranty.
Amazon $83.28Prices were last checked October 30, 2026 and are subject to change; the price and availability shown by the retailer at the time of purchase apply.
Each factor is scored 0-100 against the same fixed reference points for every split diesel heater; a clear win is highlighted. How we rank explains each one.
| Factor weight | Espar Airtronic M3 D4L | TJHSM 5kW Diesel Heater |
|---|---|---|
| Overall rating | 3.4/5 | 2.9/5 |
| Value 25% | 11 $419 per kW ($1,675, 4 kW) | 50 no credible heat rating (neutral score used) |
| Type approval 20% | 100 type approved (ECE R122) | 0 no type approval published |
| Controls and safety 15% | 65 holds a set temperature, automatic altitude; no CO sensor | 57 timer |
| Power draw 15% | 51 up to 37 W running | 50 power draw not published (neutral score used) |
| Warranty 15% | 50 warranty not published (neutral score used) | 50 warranty not published (neutral score used) |
| Low setting 10% | 79 down to 1.1 kW | 50 lowest setting not published (neutral score used) |
| Espar Airtronic M3 D4L | TJHSM 5kW Diesel Heater | |
|---|---|---|
| Heating | ||
| Heat output (maker) | 4 kW | 5 kW |
| Lowest output | 1.1 kW | - |
| Fuel burn | 0.12 to 0.49 L/h | - |
| Build | Split (installed) | Split (installed) |
| Power | ||
| Supply | 12V | 12V |
| Running draw | 6 to 37 W | - |
| Starting draw | 105 W | - |
| Controls and safety | ||
| Thermostat | Yes | - |
| Automatic altitude | Yes, to 18,050 ft | - |
| Timer | - | Yes |
| Remote | - | Yes |
| CO shutoff | No | - |
| Type approval | ECE R122 | None published |
| Build | ||
| Dimensions | 14.8 x 5.5 x 5.9 in | - |
| Weight | 9.9 lb | - |
| Released | 2021 | - |
