How We Review Products
We read each product's official Amazon listing, keep only what the manufacturer states, check that the numbers add up and calculate a score out of 10 with a public formula: every product starts at 5 and earns points for what its listing declares. Missing data earns nothing. There is no physical testing and no paid placement.
Our method is simple and checkable: we only use what the official listing states, we check that the numbers add up, we show our math and we publish the score formula.
Where does the data come from?
From each product’s Amazon.com listing (Amazon.es for the Spanish site): title, bullet points and technical table. We keep the exact phrase each figure comes from and convert to metric, adding US units where they help (1 BTU/h = 0.293 W; 1 CFM = 1.699 m³/h).
If a listing contradicts itself or promises something impossible, we say so on the product page. If a figure is missing, we write that the maker does not publish it.
What sanity checks do we run?
- Diesel heaters: 1 L of diesel ≈ 10 kWh, so peak output cannot be much more than maximum fuel use × 10.
- Air conditioners: there must be a compressor. Evaporative “air coolers” are not air conditioners and never enter our rankings.
- Insulation: the claim must fit the material and thickness. “Reflects 97% of heat” describes radiant heat only, and an R-8 in 1/4 in is not physically possible.
- Power: watts = volts × amps to see what fits on a hookup, and Wh ÷ W for battery runtime. Try the RV power calculator.
How is the VanThermia score calculated?
Every product starts at 5 out of 10 and earns points by type; maximum 10, minimum 0.
Diesel heaters: +1 ECE R122 approval stated · +1 remote or app · +0.5 altitude mode · +0.5 running draw ≤ 40 W · +0.5 minimum fuel ≤ 0.2 L/h · +0.5 ≤ 45 dB · +0.5 exhaust kit · +1 warranty ≥ 2 years (+0.5 for 1 year).
Propane and gas heaters: +1.5 low-oxygen sensor (ODS) · +1 tip-over shutoff · +0.5 indoor-rated by the maker · +0.5 catalytic · +1 warranty ≥ 2 years (+0.5 for 1).
Electric heaters: +1 lowest setting ≤ 750 W · +1 tip-over shutoff · +0.5 overheat protection · +0.5 thermostat · +0.5 frost mode · +0.5 ≤ 45 dB · +0.5 warranty ≥ 2 years.
Rooftop and parking AC: +1 heat pump · +1 cooling ≥ 2,000 W (+0.5 ≥ 1,500) · +0.5 efficiency (cooling ÷ draw) ≥ 3 · +0.5 ≤ 50 dB · +0.5 remote · +0.5 ≤ 30 kg · +1 warranty ≥ 2 years (+0.5 for 1).
Portable AC: +1 cooling ≥ 1,000 W (+0.5 ≥ 600) · +1 runs on 12/24 V · +0.5 built-in or add-on battery · +0.5 heat mode · +0.5 ≤ 52 dB · +0.5 ≤ 20 kg · +0.5 warranty ≥ 2 years.
Roof vent fans: +1 reversible · +1 vents in the rain (cover or sensor) · +0.5 thermostat · +0.5 remote · +0.5 ≥ 6 speeds · +0.5 airflow ≥ 1,000 m³/h · +0.5 warranty ≥ 2 years.
12 V fans: +1 battery ≥ 5,000 mAh · +0.5 oscillation · +0.5 ≥ 4 speeds · +0.5 timer · +0.5 ≤ 40 dB · +0.5 remote.
Dehumidifiers: +1 capacity ≥ 10 L/day (+0.5 ≥ 2) · +1 works in the cold (desiccant or ≤ 5 °C) · +0.5 humidistat · +0.5 auto shutoff · +0.5 ≤ 40 dB · +0.5 warranty ≥ 2 years.
Insulation: +1 stated λ ≤ 0.040 W/m·K · +1 thickness ≥ 10 mm (+0.5 ≥ 6) · +0.5 closed-cell · +0.5 self-adhesive · +0.5 fire rating stated · +0.5 ≥ 5 m² · −1 for impossible claims.
Window covers: +1 external · +1 ≥ 3 layers (+0.5 for 2) · +0.5 vehicle-specific · +0.5 blackout · +0.5 set of 3 or more.
CO detectors: +1.5 standard stated (UL 2034 / EN 50291) · +1 electrochemical sensor · +0.5 10-year battery · +0.5 display · +0.5 also detects gas.
Thermometers: +1 app or Wi-Fi · +0.5 two or more sensors · +0.5 humidity · +0.5 alarm · +0.5 range ≥ 50 m.
What don’t we do?
We don’t physically test products or publish testimonials. When we explain how a diesel heater works or why a camper condenses, we are describing physics and the technology, not our own measurements. We don’t accept payment to appear; we are funded by Amazon Associates, as our about page explains.
Which outside sources do we use?
For safety we cite official sources: the NHS for carbon monoxide symptoms, UL 2034 and EN 50291-2 for CO alarms, UNECE Regulation 122 for vehicle heating systems and the EPA for indoor humidity. We link them in each guide, as in carbon monoxide in campers.
How often is it updated?
We recheck listings every 60 to 90 days. If a product changes or disappears, we update the page and its date. If you spot an error, reach us through the contact page.
Frequently asked questions
Why does the score start at 5?
Every product in the catalog already clears a minimum: an available listing with enough data to compare. The score measures how far it stands out above that minimum.
What happens when a listing leaves out a figure?
That criterion adds zero. We would rather penalize missing information than assume a value, even if a good product ends up scoring lower than it deserves.
How do you catch inflated heater ratings?
With basic physics: a liter of diesel holds about 10 kWh, so a heater that burns at most 0.36 L/h cannot deliver 8 kW. We show that math on the page, and that product never wins.
Does the score decide the ranking?
It sets most of the order, but not all of it. Whether the numbers add up and how well a product fits the use come first.
How often do you check listings?
Every 60 to 90 days, and sooner if a reader reports a change. The review date appears on every page.