Why a diesel heater matters
The van gets cold at night. Even in August. A diesel heater draws from the van's fuel tank, runs quietly on 3-5 amps, and holds whatever temperature you set. Your partner will consider it a non-negotiable. If you're buying a pre-converted van without one, factor in £800-1,200 to retrofit.
The two brands worth specifying are Webasto and Autoterm (formerly Planar). Both are proven, both have good UK support, and both are compatible with aftermarket phone controllers. The Eberspacher (now branded Espar) is also available but less commonly fitted in conversions.
Whatever heater unit you specify, the controller is where you gain or lose quality of life. The basic rotary knob controllers that come with budget heaters are frustrating. At the time of writing, the Autoterm Comfort Controller has a timer, thermostat, remote temperature sensor, and is worth specifying regardless of which heater unit you choose. At around £120, it's a cheap but meaningful upgrade, and can be combined with an optional SIM/phone app to warm your van up remotely before you arrive or go to bed.
Prices shown as a guide - they can change at any time.
Always check compatibility with your specific vehicle before buying. Van models, years, and conversion specs vary - we can't guarantee every product fits every setup. If in doubt, contact the manufacturer or your converter.
What to specify at conversion time
If commissioning a conversion, specify the heater explicitly in your brief - don't leave it as "a diesel heater". Ask for: the exact unit (Webasto or Autoterm), the controller (Comfort Controller or equivalent), and check the fuel pickup and ducting/vent options so you know where heat is coming from. You'll need to leave items - clothing etc - clear from the vent for safety in use.
Any decent converter can retrofit a heating system, but there are also mobile specialists who offer home fitting - the T6 Forum is always a good place to find recommendations.
If buying pre-converted, test the heater during your viewing. Turn it on cold, let it run for 10 minutes, confirm it reaches temperature without error codes, and check there's no diesel smell inside the van once it's warm.