Managing van condensation during winter – Top 4 tips


In the winter a window cleaners van can generate excess moisture that form into huge droplets of water. These droplets usually cover the roof and drip to the floor or the pure water system bolted into the back. The water will cover the top of your system in small pools.

Condensation is not a problem during the summer months but through the winter months the air humidity is higher. In below freezing temperatures these droplets will freeze inside the vehicle.

The situation can be made worse with the use of heaters. Heaters used to keep van systems RO/filters from freezing overnight create moisture-packed warm air that not only adds to the air humidity but when this warm air hits with a cold surface, this rapidly cools down the warm moist air produced that then turns into liquid droplets on the cold surfaces in the van.

WARNING: When condensation builds on the roof of a van, do not use electrical heaters or hot air fans with openings to filaments and electrics. Making makeshift covers to protect the electric heaters from falling water droplets is also not a good idea.

Heaters such as electric ‘Oil heaters’ with a thermostat offer a much safer option if you wish to keep an ambient heat overnight and prevent freezing. Please research the heater you wish to use and use the one you feel safest.

How to Prevent Condensation

The best and most effective way in reducing condensation is through ventilation. It is necessary to have a constant airflow throughout the van bringing cooler, drier air in and pushing humid air out. This is especially true when adding an excess amount of moisture to the air such as a tank full of pure water.

Cracking open some windows might not sound like a very comfortable idea in the winter; but secondary solutions such as dehumidifiers and moisture absorbers will simply not be successful. A van is a very tiny space and humidity needs somewhere to go.

A more extreme way is to install electric venting fans, one at each side of the van. The problem is that you have to take the plunge in cutting holes through the roof of the van, something you might not be comfortable doing. The height of the fan vents may also impede your roof ladder rack so if you choose to do this, plan it out well.

We have heard of those tips and tricks such as leaving trays of cat litter out on the floor of the van, dangling cat litter in socks from the roof, using moisture absorbers for caravans. Whereas using a hanging moisture absorber ( such as used in caravans) will collects a tiny bit of the huge amount of moisture in your van they will not deal with the problem.

Insulating the roof is another possibility, but be aware that moisture can get trapped in between the roof and the insulation.

We have compiled a routine that does not consist of hacking holes into the roof of your beloved van or make you look like the crazy ‘cat lady’ from the Simpsons!

Left unchecked without a maintenance program excess moisture can turn quickly into mold. Mold will cause health issues if not tackled with.

Follow these top 4 tips at the end of every working day.

1 – Drain your tank. The less moisture you add to the already high humidity cold air the better. If not practical during your mid week schedule, at least consider a complete empty of the tank for the weekend.

2 – Wipe all access moisture from the pure water system, the roof and any side panels in the morning EVERY DAY.

3 – After EVERY working day, remove all hose reels, damp window cleaning cloths, buckets with soapy water and wet applicators and water fed poles and bring them in doors. By doing this, you are not only bringing these items in from any potential deep freeze but you are removing extra sources of moisture.

4 – Air your van in the morning. Moving ventilation is the ticket. In the morning when you are loading your van and prepping it for the days work, open all the doors; the side door, the back doors and wind down fully the windows. Turn the engine on and get the internal fans running. You might be doing this all ready if there is a frost on the ground. Once you are in your way to your first job, keep the windows down for a little longer so that the air flow can remove any excess moisture left in the back of the van.

In a nutshell it’s a routine you have to stick with. In the summer you will work differently to the winter. Allow in your work routine the additional time for these top tips, as if when you allow extra time to defrost the van after a deep overnight freeze.

In vans where the driver sits in a separate compartment ( drivers cab) to the rear hold like a Ford Transit or Vauxhall Vivaro, the driver will be as dry as if in a car, usually.

The condensation tends to be kept in the back area of the van where the water fed pole system sits, however, with the increased load capacity and lower costs of smaller vans nowadays more and more window cleaners will be sharing the same high humidity environment as the pure water system. That is because smaller vans do not have separate driver cabs and will share the environment of the pure water system.

An increased exposure to health affecting mold is more likely if this routine is not carried out and is especially important for those sharing the pure water system environment.