Keep the cab fires burning some hot tips
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You can use a lot of diesel by leaving an engine idling just to keep the cab warm. David Wilcox has found out how much this costs you and has looked at some alternatives to calculate the savings
A COUPLE of months ago a Scottish lorry driver from Mull almost died in his cab during the night. He was suffering from hypothermia; the temperature of his body's core was so low that the vital organs began to falter.
This particular driver was en route from Scotland to Poland and was just 50 miles from Warsaw when his lorry broke down at night. No engine meant no heater and hence the onset of drowsiness as the temperature in the cab plummeted. Disaster was only averted when a passing motorist stopped and an ambulance was summoned just in time to save the driver's life.
Now while not every driver is unlucky enough to break down on a winter's night in Poland, night-time temperatures here in the UK even at this time of year can still be low enough to make life uncomfortable. That tractive unit sleeper cab that looked so cosy in the brochure can be mighty cold for the driver trying to get some much-needed sleep.
There are two ways of raising the air temperature inside the cab at night: leave the engine idling to keep the engine coolant hot and so enable the heater to still function, or install an independent cab heater.
The idling engine method has two major advantages — it requires no additional capital expenditure, and the engine as well as the cab is kept warm so you have instant driveaway the next morning.
There are several disadvantages. It is noisy, both for the driver inside and anybody in the vicinity trying to sleep, particularly if the lorry is in the middle of a crowded overnight lorry park. And a diesel engine idling lumpily is not really akin to the gentle rocking of a crib.
But the major disadvantage is that it is such an expensive way of heating the cab when you consider the amount of fuel used. Running a 250-300bhp diesel engine solely to provide the relatively small amount of heat needed to keep the cab warm ranks alongside the "steamhammer to crack a nut"technique.
Even a well-tuned engine of this size idling under no load at 600-700rpm will typically consume 1.6 litres (about a third of a gallon) of diesel an hour, adding up to 13 litres (almost three gallons) during an eight hour night. That is £5-worth of diesel per night in running costs, not to mention the small amount of additional engine wear and maintenance. Extended periods of idling tend to lead to coking up and a lumpy tick-over.
So how do the alternatives compare? I have looked at three widely available cab heaters.
Webasto is a subsidiary of Smiths Industries and the company's heaters are made in Munich, West Germany. The model designed for air heating in lorries is the HL2011.
This unit weighs 7kg (15.5 lb) and measures 440mm long, 160mm wide and 200mm high (17 x6x8in) and is intended to fit inside the cab on the floor, either behind the seat or under the bunk.
It runs on diesel drawn up from the vehicle's main fuel tank via an additional narrow bore pipe inserted in the top of the tank. There is an electric fuel pump within the heater body to draw up the diesel but if the height from the tank level is more than 0.6m (2ft) a supplementary pump is fitted at the tank end.
Outside air is drawn in by an electric fan via an inlet through the cab floor and mixed with the diesel so that the mixture can be atomised and ignited by a glow plug to burn in the unit's heat exchanger. Cold air in the cab is also sucked in by the fan and passed around the heat exchanger where it is warmed and expelled at the other end of the heater, thus heating the cab.
Electrical connections are needed for the unit's fan motor and there are three pipes to go through the cab floor: one for the fuel pipe from the diesel tank, one for the combusion air inlet (these two are together so that only one hole is needed) and an outlet for the exhaust gases from the heat exchanger.
The heater can be mounted outside the cab to cut out the small amount of noise it makes but this will mean that trunking is required to carry the warm air into the cab.
Thermostatically controlled as standard, a 24-hour time switch is also available as an optional extra to switch the heater on automatically when the driver is away or asleep. Webasto says that most customers do not choose this option for lorry applications, although it is useful in coaches for pre-heating on a cold morning.
The maximum heat output is 2.3kW. The electrical power consumption is 35-50 Watts, which ; roughly equivalent to leaving [ne headlight on, so the drain on ne batteries is not excessive. It onsumes diesel at the rate of .28 litres (0.5 pint) an hour Mich equals 2.3 litres (0.5 gal)n) for the eight-hour night — bout 90p in diesel costs.
List price of the Webasto IL2011 is £399 plus vat, and the Iptional 24-hour time switch osts a further £69.50. Most perators will fit the heater nemselves (it takes about a day) Ithough there are fitting agents round the country. Competitive iscounting would probably lean that an operator could get le basic heater supplied and tted for not much over £400 lus vat.
There is no routine maintennce to plan for although items uch as the glow plug or a motor earing could fail after a few ears; replacements are availble.
Webasto also has a heater that Istead of directly heating the ab air heats the engine coolant rid by switching on the ehicle's own heater blower fan fill also heat the cab. Although is has the benefit of keeping le engine warm it uses four mes as much diesel as the L2011, has a greater electrical rain on the batteries, costs vice as much and is much more omplex to fit.
The Eberspacher D1L cab eater is another air heater very Imilar to the Webasto HL2011, Iso made in West Germany. It )o uses diesel fuel burnt in a eat exchanger over which the ab air is passed and so farmed, but there are a number I specification differences.
The heat output of the berspacher is slightly lower at .7kW. There is a corresponding enefit in a marginally lower dieal fuel consumption figure of .23 litres (0.4 pint) an hour which is the equivalent of 1.8 litres (0.4 gallon) for the eighthour night. That is about 72p in diesel costs.
Measuring 355mm long and 1 30mm wide (1 4x 5in), the Eberspacher unit is also slightly smaller than the Webasto. This can be partially explained by the remote position of the fuel pump; instead of being in the heater it is at the vehicle's diesel tank where it draws up the fuel from a top-feed pipe.
Control is also thermostatic with an optional 24 hour timer for pre-setting. Typical price for the Eberspacher K1L is around £400 including fitting, plus vat. The timer costs £38 plus vat.
The company has 30 fitting agents in this country and Eberspacher much prefers operators to use these agents rather than attempt a diy fitment.
An altogether less costly and less sophisticated alternative to the Webasto or Eberspacher type of air heater is the catalytic heater, such as that made by Ross James Heaters of Walsall.
It operates on bottled butane or propane gas, similar to that used in camping. This gas is directed onto a pad which incorporates a platinum catalyst. The result is a chemical reaction that gives off heat below flame temperature. So although the temperature is much lower the catalytic system can claim to be safer and cleaner than conventional combustion because it has no flame. It is also silent.
Ross James' H150 model has a catalytic pad in a frame 254mm x 305mm (10 x 12in). It is just 76mm (3in) deep and is typically mounted on the rear bulk-head of the cab. The gas bottle is ideally located outside the cab — on a tractive unit's catwalk is one possibility.
The heat output from the H150 is very much lower than the previously-mentioned heaters — 0.9kW — and there are no refinements such as thermostatic control or timers. But neither is there any electricl power requirement and the running costs are very low. It uses gas at the rate of 70 grams (0.16 lb) an hour, which works out at 0.56kg (1.28 lb) for the eight-hour night.
The actual running cost depends greatly on the size of the gas bottle used. A 7kg bottle, which is the most convenient, costs around £5 and would give 100 hours burning; the eighthour period would cost 40p. A 13kg bottle is proportionately cheaper at £7 and would last 185 hours but is somewhat cumbersome. An eight-hour period would then cost 30p.
In addition to exceptionally low running costs, the Ross James H150 is very inexpensive, at £82.50 plus vat. A smaller version, the H100 gives half the heat output with half the gas consumption and can be used as free-standing unit with the heater hung on the gas bottle so that it is portable — useful for the driver who uses a different vehicle each day, although the heat output is very limited. This costs £67 plus vat.
Webasto, Smiths Industries Ltd., Units 17/18 Station Lane Industrial Estate, Witney, Oxon 0X8 6AS.
Eberspacher (UK) Ltd., Fibbards Road, Brockenhurst, Hants SO4 7RD.
Ross James Heaters Ltd., Longwood Lane, Walsall, West Midlands WS4 2JR.