Winter in the Cairngorms: how a HubDub holds up in the cold

Builders are quick to tell buyers that their van will be "winter-ready". The honest version is that winter performance depends on a handful of specific spec choices, and on a couple of habits that nobody mentions on a forecourt. This piece walks through what actually matters when overnight temperatures drop below freezing.

The numbers below are the figures we use when speccing a build for genuine winter use, in order of impact.

The heater

An Eberspacher D2 or Webasto Air Top 2000 on its lowest setting is enough to keep a Crafter or Sprinter cabin steady at fifteen degrees overnight in sub-zero conditions. Diesel use is roughly 0.6 to 1.0 litres per night. The trick is sizing the heater for the smaller setting rather than the bigger one. A 5kW heater used at 30% draws more diesel and runs less efficiently than a 2kW unit at 70%.

The water

An uninsulated 90L freshwater tank will freeze on a night below minus three. A tank with a heater pad on a thermostat will not. The pad draws around 30W when active, which is a rounding error against a 600Ah bank. We fit one as standard on every winter-spec build.

The batteries

Lithium will refuse to charge below zero degrees. With a battery heater pad on the lowest tier, that is no longer a concern. We see almost no usable capacity loss across a winter trip in builds with a heated bank. Without one, owners can wake up to a battery that will discharge but will not recharge until the cabin warms.

Condensation

Condensation is the real enemy in winter. Two adults breathing for eight hours produce roughly a litre of water that has to go somewhere. The simple fix is a MaxxFan or equivalent vent set to extract on a thermostat for ten minutes before the heater starts each morning. We fit a MaxxFan with thermostat by default on every build.

Habits that matter more than spec

Owners who use their vans regularly in winter all do the same three things. They run the heater overnight rather than blasting it in the morning, which uses less diesel for the same comfort. They wipe the inside of the windscreen before bed, which prevents the worst of the morning condensation. And they leave a microfibre cloth by the slide door for the wet boots that will inevitably arrive.