Espar Airtronic S3 D2L
#2 in SplitFull review
For van, truck and boat owners who want a quiet, type-approved 2 kW heater that works at high altitude. It costs much more than clones but is built to run for thousands of hours.
Amazon $1,250$1,250
The Espar Airtronic S3 D2L is the better diesel heater overall, rated 3.5 to 3.3. The Espar Airtronic S3 D2L leads on controls and safety. The Espar Airtronic S3 D2L costs $625 less ($1,250 vs $1,875).
Webasto Air Top Pro 25
#7 in SplitFull review
For van and truck owners who want a new type-approved 2 kW heater with altitude adjustment and a very low idle setting, or a drop-in replacement for an Air Top 2000 STC. It costs far more than clone heaters of the same size.
VMACS $1,875$1,875
Prices 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.
Which should you buy?
- Choose the Espar Airtronic S3 D2L for controls and safety (holds a set temperature, automatic altitude; no CO sensor vs holds a set temperature, automatic altitude; no CO sensor).
Scores side by side
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 S3 D2L | Webasto Air Top Pro 25 |
|---|---|---|
| Overall rating | 3.5/5 | 3.3/5 |
| Value 25% | 2 $568 per kW ($1,250, 2.2 kW) | 0 $750 per kW ($1,875, 2.5 kW) |
| Type approval 20% | 100 type approved (ECE R122) | 100 type approved (ECE R122) |
| Controls and safety 15% | 65 holds a set temperature, automatic altitude; no CO sensor | 50 holds a set temperature, automatic altitude; no CO sensor |
| Power draw 15% | 73 up to 27 W running | 50 power draw not published (neutral score used) |
| Warranty 15% | 50 2-year warranty | 50 warranty not published (neutral score used) |
| Low setting 10% | 96 down to 0.8 kW | 100 down to 0.7 kW |
Specifications
| Espar Airtronic S3 D2L | Webasto Air Top Pro 25 | |
|---|---|---|
| Heating | ||
| Heat output (maker) | 2.2 kW | 2.5 kW |
| Lowest output | 0.8 kW | 0.7 kW |
| Fuel burn | 0.1 to 0.27 L/h | - |
| Build | Split (installed) | Split (installed) |
| Power | ||
| Supply | 12V | 12V |
| Running draw | 6 to 27 W | - |
| Starting draw | 90 W | - |
| Controls and safety | ||
| Thermostat | Yes | Yes |
| Automatic altitude | Yes, to 13,120 ft | Yes, to 18,045 ft |
| App | - | No |
| Timer | - | No |
| Remote | - | No |
| CO shutoff | No | No |
| Type approval | ECE R122 | ECE R122 |
| Build | ||
| Dimensions | 12.2 x 4.5 x 4.8 in | 12.6 x 5 x 4.9 in |
| Weight | 5.5 lb | 6.5 lb |
| Warranty | 2 years | - |
| Released | 2021 | 2026-07 |