Much as we all bemoan cold and wet British weather, stifling heat isn’t great either.

We Brits have learnt to wear layers, and can peel off or pile on the clothes according to our changeable climate.

But when the mercury rises and the climate becomes uncomfortably sticky, and you’re already down to beachwear, what do you do next to cool down further?

This is where motorhomes with habitation air con come into their own, particularly at night when those that have none can become unbearable sweat-boxes.

And there’s a good argument that air conditioning is almost essential if you take your ’van over to the Continent in the summer months.

However, retro-fitting air conditioning is neither cheap nor easy – and while standalone air-con units are available, they tend to be big, heavy and extremely noisy.

What is an evaporative cooler?

Fortunately, there is a third way that sits between fans, which are largely ineffective in really hot weather, and full-blown air conditioning.

Evaporative coolers – also known as chillers, air coolers, or swamp coolers – are in effect powerful fans that route the air they expel through a wet matrix, which drops the air’s temperature.

Exactly how much depends on the air conditions. That’s because these units work, as their name implies, by the warm air passing through the damp matrix, and evaporating some of that water into airborne water vapour.

This process consumes thermal energy, which is why overall air temperature decreases.

But it stands to reason that warm, dry air will evaporate more moisture – dropping the temperature more effectively – than hot and humid air.

In short, evaporative coolers can be a cheap and effective way of cooling down, but they must be used carefully.

Use with care

When used inside, for instance, it’s important to keep windows open and, ideally, place the unit in front of said open window.

That’s because these coolers make the air more humid, which can be counterproductive in already hot and humid conditions.

And while, optimally, the process can knock 7C off air temperature, that’s only true in hot and dry climates – expect performance in humid UK summers to be half that at best.

Also realise that evaporative coolers should be used like a fan rather than air conditioning.

Sit close enough to the unit to feel its output and that colder air will be cooling and refreshing, but don’t expect overall room temperature to be dramatically lower, as it is with a decent air-conditioning system.

Should I buy an evaporative cooler for my motorhome holidays?

So are these units really worth buying?

Well yes, if used correctly. Evaporative coolers provide a degree of cooling when high temperatures render ordinary fans useless.

And, although the units are much bigger and bulkier than fans, they are around half the size – and a fraction of the weight – of a portable air-con system.

Power-wise they make sense, too. Air conditioning usually consumes around a kilowatt (4-5 amps), whereas the evaporative process is normally 100 Watts at most (less than half an amp at mains voltage), making these units usable off-grid, with the leisure battery and an inverter.

Finally, unlike proper air conditioning, they are usable and reasonably effective outside, too.

Our testing process explained

We began our tests by gauging overall cooling ability at various temperatures and humidities.

As well as measuring input and output temperatures, we also gauged how close you have to be to each unit to benefit from it – the further away the effect worked, the better.

Then we looked into practicalities such as size and weight, noise levels and features included.

Countdown timers, for instance, are useful at night, because they will shut down the unit after a pre-decided time – hopefully when you’ve drifted off to sleep.

Sleep modes, which gradually decrease the fan speed – and noise – over time, are another useful benefit.

And if you wake up in the middle of the night, boiling hot, you’ll certainly appreciate buying a unit with a remote control.

All of these models obviously have to be filled with water, so we made sure that the tanks were big enough to ensure decent running times between fills. We also factored in ease and speed of both filling and draining.

Finally, we considered any other features these products might have. Some also work as heaters, making them useful all year round, in all conditions.

Others have ionisers built in, which can actually freshen up the air no end, even before the cooling effect takes place.

Evaporative coolers – what do I need to know?

Please see photos two to seven above.

  1. The air is channelled to the right place using horizontal and vertical louvres. The horizontal ones point the air up or down, and are often manually adjustable.
  2. The vertical louvres, which direct air in a fan around the unit, are electronically operated. They can be set to a desired static position, or left to oscillate continually.
  3. On some models, the fill point for water and ice is at the top. Filling can take more time because of the long, narrow tube between the filler and the tank in the base.
  4. Units should be emptied prior to being put away, because a tankful of water can dramatically add weight. If the tank isn’t accessible, there’s usually a drain plug.
  5. More models now come with remotes – perfect for upping the air speed, or cooling down airlessly hot sleeping quarters in the middle of the night without having to get up.
  6. With a detachable tank you can use ice packs to cool the water. With top-fills, ice packs are ineffective because they rely on ice cubes to melt and bleed into the matrix.


Beldray 8-litre Air Cooler – four stars

  • Price: £99.99

While this unit doesn’t have the immediately noticeable cooling ability of Symphony’s group-test-winning DiET 8ƒi, there is a definite di„fference between the dry fan mode and activating the water-cooling process.

And, as a bonus, Beldray includes two ice packs that enhance the cooling cycle as much as possible – once they are frozen, simply place them in the 8-litre water tank.

Overall, the cooler is nicely put together, but the bargain price, predictably enough, means that the specification is pretty basic.

There’s no timer or remote control, and you need to keep an eye on the tank level to avoid running the unit dry.

Symphony DiET 8i – five stars

Practical Motorhome Editor’s Choice

  • Price: £123.85

This is easily the most effective cooler here.

The breeze emitted is noticeably chillier than that from others on test, and said breeze is strong enough to be felt some distance from the unit.

Better still, and unexpectedly, the gutsy unit is much quieter than the competition.

Outright performance aside, we like the chiller’s compact footprint (“‹30 x 33cm) and the 8ƒ-litre tank allows plenty of use between fills.

Despite the keen price and the basic appearance, Symphony hasn’t skimped on extras, such as a remote control, a timer function and a low-water alarm.

Sealey SAC41 – four stars

  • Price: £110.14

Although it managed an impressive score, we don’t wholeheartedly recommend this four-in-one evaporative cooler.

For a start, cooling performance trails the top models quite considerably. You can feel the difference between dry fan and wet cooling modes, but the effect is nowhere near as pronounced as with some units here.

And the slightly bulky 28 x 40cm footprint, plus a portly 6.5kg weight, means that this isn’t a great choice if space is at a premium.

On the other hand, the cooling performance is fine for the UK, and the unit boasts plenty of features, not least an ioniser air purifier and a 1-2kW heater.

Screwfix 4426K – three stars

  • Price: £69.99

This is the cheapest evaporative cooler in our test and, we suspect, one of the cheapest on the market.

Yet, despite this, Screwfix hasn’t withheld the extras. The cooler boasts a timer and comes with a remote control. And the 11-litre tank gives several hours of service between water refills.

But the design is pretty old-fashioned, utilising a motorised roll of material that passes through the water tank at the bottom and then in front of the fan – unfortunately, its chilling performance just doesn’t compare to newer designs.

Filling is slow, too, thanks to a small tube running between the top-mounted fill point and the tank in the base.

Prem-i-Air EH1770 – three stars

  • Price: £165

Here’s a product that we imagined would make a great budget alternative to Symphony’s DiET 8i, until we researched prices.

This is no entry-level bargain, costing some £40 more than the ultimate winner, and that’s a shame because there’s a lot to like about it.

Cooling ability is just sub-DiET 8i level, and improves further when the two ice packs supplied are frozen and placed in the tank.

The diminutive 24 x 29‰cm footprint is also a great bonus in smaller ’vans. But the lack of a timer, remote, or any other extras seems a little mean at this price level.

Honeywell CS10XE – two stars

  • Price: £229.99

Don’t be fooled by the picture. This model may look like an oversized tower fan, but it’s one of the biggest and heaviest here – the footprint is 40 x 34cm, it’s 80cm tall, and it tips the scales at 8.4kg.

But the unusual height is due to the whole base being a fully detachable 10-litre tank, making it the easiest unit on test to fill or drain.

The product works well, too, with chilling performance that just trails the DiET 8i.

Add into the mix the integral ioniser, the timer, a remote control and a sleep-mode fan setting, and this justifies a slightly premium price, but not one this high.