Diesel Heater or Gas Heater for a Caravan.
Most caravan dealers will direct you to a Gas Heater as it is a slightly easier install (less time consuming) and the Truma E2400 Gas Heater is a pretty quiet heater, but this is a bit simplistic.
In Europe and the United States there are many, many models and brands of gas heater. But due to deaths in caravans from using gas heating, the regulations covering Caravan Gas Heating are very strict in Australia, so far the Truma E2400 is the only complaint model available here. To make this happen Truma removed one of the heat settings to accommodate the required Carbon MonOxide monitoring. This means the heater has only one heating output of 2400 watts, so this comes on and off (controlled by a rotary dial type thermostat), this makes for one of the 3 issues against the heater, not an issue that bothers everyone, but it needs to be noted. This issue is where the temperature difference, from when the heater shuts off thermostatically, to, when it comes back on is quite large. The specification is 4 degrees, so if you have the heater turn off at 24 degrees then it will drop to at least 20 degrees before it switches back on.
The E2400 is a good heater, but, it has been replaced with the Truma VarioHeat Eco.
The new heater from Truma overcomes the 3 issues using a E2400 Gas Heater. 2nd issue is the Thermostat control knob - this is a rotary type of control knob, numbered 0-5, all other types of heater use a Digital control knob and with all diesel heaters having at least 3 flame/fan speeds - you get much better room temperature control, set to an actual temperature. The 3rd issue will, again, not effect most people, we don't recommend the heater for serious off-road usage, we have found the fan motor mounts to be weak and allow the fan to break from its mounts in hard off road usage, it appears this has been recognized by Truma and the fan motor on the new varioheat model has different fan mounting.
So the replacement Truma Varioheat is now a modern, great, maintenance free heater.
Diesel heaters are generally much more robust and slightly cheaper to run (this is debatable, but in theory is correct). They do make slightly more noise, from the air intake and exhaust (outside, underneath the van) when initially heating the van. When the van has warmed up the noise abates and the sound inside the van is quieter than the Truma Varioheat gas heater. The noise inside the van from a diesel heater is quieter than a 240volt electric fan heater and is certainly quieter than a reverse cycle air-conditioner.
The Truma Vairoheat has grown a bit in size (as all the electronic controls are inside the heater) and will definitely take up more room inside your van than a diesel heater.
I believe one way to make your decision on which type of heater is for you is quite simple. If you have a on road van, buy a Gas Heater. If you have an off-road van and carry spare diesel already, then purchase a Diesel Heater. For a motorhome use a Diesel Heater for 2 reasons, 1) you can tap into your existing fuel tank and 2) a gas heater is very difficult to find a legal location to mount.
For a comparison of different diesel air heaters, click here,