Fleet News

Refrigeration feature: cool, calm and collected

GET the specification wrong on a fridge van and you risk not just higher running costs but a ruined load unfit for eating. Sharon Clancy offers some expert advice on choosing the right temperature controlled van bodies.

Buying a temperature-controlled van is a complex affair. The starting point is to identify the type of load. Is the product chilled, frozen or deep frozen? Frozen foods require more body insulation and a more powerful refrigeration unit to keep the air temperature colder in the load box. With some loads (blood products, for example) the temperature must remain above a certain point.

The major van manufacturers all offer off-the-shelf temperature controlled van conversions. They will use one or two bodybuilders and maybe offer a couple of options on the refrigeration unit. Citroen, for example, offers Somers conversions, while Renault is linked to GRP. Vauxhall launched two fridge conversions for the Vivaro van at last month's CV show.

Van dealers, however, are not temperature control experts: if you want something more complicated, such as a dual temperature van, check with the bodybuilder direct and the refrigeration unit manufacturers. Rental companies such as Dawson and Via have a wealth of experience and it's not in their interest to hire you an under-performing vehicle.

Van or box body?

You also need to decide whether an insulated panel van or chassis-cab with a separate body is the better route. There is plenty of advice out there – it's just a question of tracking it down.

The growth of supermarket home deliveries has driven a lot of development work on 3.5 tonners. There has been a shift away from the panel vans once considered more acceptable for domestic deliveries, in favour of separate bodies which last longer and can be tailored to suit each food store's delivery set-up.

Interior plug-in or fixed bulkheads can split the load space into two temperature zones: either chilled and frozen, or chilled and ambient. Some operators choose panel van conversions because delivery times can be quicker. GRP Group developed the Glacier 35 series to combat this. It promises delivery in two to three weeks. There are chill and frozen versions, and GAH Javelin refrigeration systems and single rear door are standard.

Panel vans

So what should you look out for? Panel van conversions are built either with wet-lay insulation or modular panels. Wet lay is cheaper: a timber frame and insulation are topped with a wet-lay laminate coating. Styrofoam and polyurethane are the most common, but do check – there are horror stories of cheap conversions using newspaper and roof wool-cladding.

Wet-laid insulation cannot be removed and it is less efficient at preventing heat entering the box because the metal ribs in the side walls act as a thermal bridge. With a vacuum-pressed modular panel, there are no thermal bridges so the thermal efficiency of the body is greater.

That has knock-on benefits: the power drain from the vehicle engine drops because the fridge unit is working less hard, so fuel consumption increase is minimised.

Modular panels can be twice the price, but quality is more consistent and some, including those from Paneltex, are designed to be removed and reused on a new van. Panel construction varies. Paneltex uses scratch-resistant Kemlite for interior surfaces. RVL adapts according to customer demand: on the LDV Convoy conversion, for example, it uses a combination of modular panel topped by a wet laid laminate to create a seam-free hygenic interior.

Box bodies

Temperature-controlled bodies are not cheap: many are designed to have a minimum life of six to 10 years before the thermal properties start to degrade. The body-on-chassis option is more expensive at the outset but has one major advantage: it will last the life of two, if not three, chassis and can simply be transferred.

RVL uses five-element panels bonded together. Solomon uses a three-element panel reinforced with woven roving material and a combination of bonding and aluminium mechanical joints to help resistance to knocks.

Refrigeration units

Refrigeration units on small vehicles have had a bit of a makeover in recent years. The ugly roof-top box housing the condenser part of the system has gone: on some it has disappeared altogether into the engine compartment. But where that is not technically possible, it is now in a much sleeker, low-profile aerodynamically styled box. One popular panel van option is to take a medium- or high-roof model and inset the fridge unit into that.

Van refrigeration systems are direct-drive units, working in a similar way to a car air-conditioning system. Diavia Frigosoft units (sold in the UK by Eberspächer) are usually behind the radiator grille and use the same condensers that parent Delphi Automotive Systems uses for car air-conditioning systems.

Evaporators and fans – the part you can see inside the body – used to take up a lot of interior space, but are now much slimmer. For example, the new evaporator on the Thermo King V-250 Plus is half the depth of the old unit at 145mm, while the unit on the V-200 and V-090 is even slimmer at 130mm. Some models are roof-mounted, so there is even less intrusion.

Refrigeration manufacturers focus on two key factors: capacity and air flow. Capacity is measured in watts and indicates how much heat the refrigeration unit can remove from the system in a given period and air flow is the amount of air it blows into the body per hour.

Typically manufacturers quote the number of watts capacity at 0 deg C and minus 20 deg C. The higher the capacity, the easier it is for the unit to maintain the box temperature. The air flow rate is important to make sure cooled air reaches the back of the vehicle, eliminating hot spots.

A fridge unit designed for chill operations might just cool a box carrying frozen food provided it was not for very long and the door stayed shut. A unit that is adequate for a SWB van might struggle with the extra cube on a LWB model.

Getting the maths wrong on this one can result in spoiled cargo, so it's worth checking with either the fridge unit manufacturer or bodybuilder that the fridge unit will do what you want it to. Carrier has set up a dedicated and easy-to-use website for selecting Xarios van fridge units – It's much easier these days to buy the right fridge unit for the job because the latest units are modular, so you can mix and match components to get the right unit. Carrier's Xarios range covers bodies from 15 to 44 cubic metres. Thermo King's C-series has been developed specifically for chilled applications, while the V-250 Plus produces 2,500 watts capacity at 0 deg C – 12% more than the standard V-250.

A second solution is to use a eutectic beam refrigeration system, despite the weight penalty that is incurred. Charged overnight from an electricity supply, they are silent in operation and have the big capacity that is necessary to cope with multi-drop work.

Cornish clotted cream producer Rodda, for example, makes up to 80 drops a day using its Iveco Daily 3.5-tonner. Bodybuilder Reep fitted a Hubbard eutectic beam system on the front wall, behind a false bulkhead equipped with a 12-volt fan. The bulkhead prevents the box temperature becoming too cold and spoiling the cream, while the fan speeds up delivery of cool air to the body.

Refrigerated vehicle best practice guidelines

  • Pre-cool the vehicle and defrost the refrigeration system
  • Check the product temperature
  • Keep the vehicle engine running whenever possible
  • Use curtains to reduce the amount of warm air entering the body
  • Don't leave doors open longer than necessary
  • Don't load to the roof. Restricting air flow can cause hot spots
  • Defrost regularly. If the evaporator ices up, air flow is restricted
  • Don't mix temperature-different products in the same compartment
  • Don't set the thermostat too low – chilled food can freeze
    Source: Transfrigoroute 01572 722489
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