Ever wondered about how something on your motorhome works, but couldn't ask because it seemed like one of those simple questions you should have known the answer to all along? Well, wonder no longer. Here you'll find the answer to some of those questions about your motorhome that have always been bugging you. We have worked through the alphabet, paying particular regard to safety issues.
Whether you are a novice or an old hand, there will be something here that you didn’t know before ...

A  IS FOR
AMPS
Amperes – or amps – refer to the quantity of electrical current flowing along an electrical cable. The pressure that pushes it along the cable is measured in volts. Multiplying the volts by the amps gives the amount of energy an appliance uses, expressed in watts (W).
In the UK, normal mains voltage is 230V, though it can vary slightly. The highest amperage of an electrical appliance is 13A, so based on the formula, this becomes 230 x 13, which equals 2990 watts.
The maximum amps available from the hook-up on a UK site is 16A; often it's less – 10A or 6A. Also, although a nominal 16A may be available, it is unlikely that this amount will reach your motorhome if other users are also drawing current.
Hooking up, you need to calculate the total amperage you can draw without tripping out the mains. Add up the wattage of all the appliances and then divide it by 230. Thus a 2kW heater, 125W fridge, 750W kettle, 50W TV, plus two 40W lightbulbs, totals 3005 watts, which, when divided by 230 gives you 13 amps. So if the site's supply is less than 16A, switch some items off to avoid tripping out the mains.

Alternator
This is a generator whose job is: a) to meet the power needs of a vehicle, and b) to re-charge its battery.
It is driven by a belt taken from the engine, and whereas older vehicles were equipped with a dynamo, around the mid 1960s, alternators were fitted instead. These were preferred because an alternator can charge a battery even when the engine is only running at tick-over speed – and that’s important now that motorhomes have so many electrical accessories.
In addition, an alternator is usually lighter than a dynamo and normally lasts longer.
In light commercial vehicles used for motorcaravans, alternators of different current output are often available as optional extras at the time of purchase. For instance, the Fiat Ducato has been available with 75A, 80A, and 90A versions to suit a buyer’s requirements.

Air conditioning
Most air conditioners employ compressor refrigeration principles but you may come across ‘water evaporative’ types in which warm air is cooled when it passes across a dampened filter. The former are more efficient but heavier, and usually run on mains power.
Water evaporative types are lighter and cheaper, and their low energy consumption means

B  IS FOR
BATTERY
Electrical systems in most motorhomes operate on 12 volts, making a 12v leisure battery necessary even if the van also has a 230v mains supply. Leisure batteries provide power over a long period.
Whereas a few motorhomes are equipped with a purpose-made battery compartment, many have their leisure battery fitted in less convenient locations, such as under a cab seat or alongside the spare wheel. Irrespective of the arrangement, it is essential that the hydrogen which is often produced during charging is expelled outside via a vent pipe – usually through the floor.

BRAKES
Front brakes on modern vehicles are usually self-adjusting disc units whereas the rear brakes are typically self-adjusting drum brakes with single leading shoes. The rear brakes usually have a ‘load reactive proportioning valve’ which alters the balance of front and rear braking in accordance with the weight that’s bearing down on the rear axle. ABS (anti-lock braking system) brakes are often available as an option.

BODYWORK
It’s surprising how many different materials are used in motorcaravan body shells: the cab (if not more of the bodywork) comprises painted steel, and you will find glass reinforced plastic (GRP) mouldings, sheet aluminium, GRP sheet, and acrylic capped ABS plastic. Since these have different rates of thermal expansion it stands to reason that good sealants are needed at all the junctions to take up the inevitable movements that arise in changing temperatures.

BLINDS
Windows in the living area are often equipped with either roller or concertina blinds - some are even housed within a moulded framework. Coming right up to date, the cab windscreen and side door windows can also be fitted with concertina or roller blinds for privacy.

BUTANE
Butane is one of two types of liquefied petroleum gas used in motorhomes. It is supplied in blue cylinders and burns slightly hotter than propane, the other gas. For a given cylinder size you get slightly more butane than propane. However, butane will not ‘gas’ below 1°C, whereas propane will do so down to temperatures as low as -40°C: so, butane is unsuitable early and late in the season. Many year-round motorcaravanners, prefer to stick with propane all year round.

C  IS FOR
CONSUMER UNIT
The consumer unit is like the fuse box in your home. It comprises the residual current device (RCD) which, in effect, is the main fuse controlling the whole electrical supply, and the miniature circuit breakers (MCBs) which control the individual mains circuits. There is also a test button, which disconnects the mains virtually instantaneously when pressed. Every time the motorhome is connected to a mains supply, the test button should be pressed to confirm the system is working.

CONTROL PANEL
The consumer unit is like the fuse box in your home.
It comprises: the residual current device (RCD) which is, in effect, the main fuse which controls the entire electrical supply; and the miniature circuit breakers (or MCBs) which control the individual mains circuits.
There is also a test button, which disconnects the mains virtually instantaneously when pressed. Every time the motorhome is connected to a mains supply, the test button should be pressed to confirm that the disconnection system is working - you then re-set the switch to the ‘on’ position, secure in the knowledge that the consumer unit is providing a protected supply.

D  IS FOR
DELAMINATION
Many coachbuilt motorhomes employ prefabricated floors and walls, which are made using sandwich construction techniques. The floors are constituted of upper and lower sheets of thin plywood bonded to a Styrofoam core.
The walls of many coachbuilts consist of an outer panel of aluminium sheet and an inner lining of 3mm faced plywood. The middle of this three part sandwich is a core of block insulation such as polystyrene. If the adhesive fails and the bond breaks down it is said that ‘delamination’ has occurred. This is more likely to happen to the floor, which then develops a spongy feel. One obvious sign of wall delamination is a bulging aluminium panel. Both forms of delamination can be effectively cured using a specially-formulated epoxy resin.

E  IS FOR
ELECTRICITY
Today, all motorhomes use 12v direct current (DC). Additionally, over the past 25 years or so, 230v alternating current (AC) electricity has become standard.
The 12v supply comes from the leisure battery and is used to power such items as the lights, water pump, 12v sockets, and TV aerial booster.
Theoretically, you can power 12v equipment using mains electricity, which is then distributed via the battery charger, but it is possible that some items may become damaged if powered in this way because the voltage isn’t smooth and can be as high as 13.8v. The mains, however, is used to power 230v appliances such as a battery charger, fridge, gas/electric water heater, the heating elements in blown-air heating systems and any mains appliances. However, parks and sites limit the amount of current supplied to each pitch so you’ll only be able to use a certain number of mains appliances at any one time.

ELEVATING ROOF
A number of van conversions are equipped with elevating roofs in order to provide additional headroom inside. Some types push straight upwards and four side cheeks create in-fills around the elevating section. However, most elevating roofs have a hinging mechanism although this can be along a side, at the front, or the rear. Arguably it’s not the best type of roof for winter motorcaravanners but an ideal arrangement if you’ve got to negotiate low barriers.

EBERSPÄCHER
This is a manufacturer of high quality water and space heating systems. For many years, these have been installed in boats and lorry cabs. Now the products have been specially adapted to operate in motorhomes. The fuel is either petrol or diesel and this is normally (but not always) drawn from the vehicle’s tank. Heat output is notably good, consumption is impressively low, but the products are not as silent in operation as gas appliances. On the other hand, Eberspächer systems can be operated safely when you’re on the move.

F  IS FOR
FILTERS
Motorhome water systems incorporate filters to trap dirt. However, they do not kill the microbes, which is why some motorcaravanners add a biocide, such as Aqua Sol, to the water container every time they fill it. Some water filters clean all the water entering the motorhome, whereas others only deal with the cold supply to the kitchen tap. Whichever type is used, it should always be changed regularly – usually after 4000 litres or annually, whichever milestone comes first.

FIXED-ROOF MOTORCARAVANS
Some conversions use the original steel roof of a panel van and these are the ‘fixed-roof’ models. A few vans in standard form provide enough headroom for all but the tallest users. Others only offer low headroom, and tasks such as cooking have to be carried out in a sitting position. For a long time that was the case in many VW campervans, but a few manufacturers still produce modern fixed-roof models.

FLAME-FAILURE DEVICE
For the past ten years, gas appliances in UK motorhomes have been fitted with Flame-Failure Devices (FFDs). These are minuscule probes which are heated by the gas flame. As they become hot, they generate a small electrical current which, in turn, keeps the gas valve open. If for any reason the flame goes out, the FFD cools and, in so doing, the current ceases and the gas control valve closes, cutting off the supply of gas to the burner. It takes a few seconds for the FFD to heat up during ignition, which is why it is necessary to keep the gas control knob depressed when lighting the flame.

FUSES
The 12v DC circuits in the van are controlled by the same types of fuse found in cars: tubular glass, and blade. The latter type are usually housed in a fuse block found under one of the seats, in the glovebox, or as part of the 12v control panel and are coloured according to their rating: mauve 3A, brown 5A, red 10A, blue 15A, yellow 20A and green 30A. The glass type are more likely to be found controlling individual items of equipment, their rating being written on a label inside the glass. It pays to know where all the fuses are fitted and to carry spares. One common cause of fuses failing is overloading the circuit. Another is a short circuit. If the replacement fuse fails instantly, do not use the circuit until the fault has been traced and rectified by a competent electrician.

G  IS FOR
GAS ISOLATION TAPS
In recent years, isolation taps have become the norm, enabling the gas supply to a faulty appliance to be cut off, while allowing the others to continued to be used. No attempt should be made to use a faulty appliance until it has been inspected by a suitably qualified gas technician. All the taps are likely to be found together, often in one of the kitchen cupboards.

GAS REGULATORS
Motorhomes made before 2004 were supplied without a gas regulator. Two types are available, one suitable for butane LPG, the other for propane LPG. The butane regulator is set for a gas pressure of 28m bar, while the propane one operates at 37m bar. The regulators are also been designed so that they are not interchangeable. However, all the gas appliances in the motorhome are suitable for use with both butane and propane without alteration.
From 2004 on, butane and propane supplied throughout the European Community will be at a pressure of 30m bar. As a result, all vans will be supplied with a 30m bar regulator as standard, which can take either gas. However, the two gases do require different types of flexible connecting hoses, so it's up to buyers to choose which type of gas and hose to use, or to keep both types of hose on board. Regardless of the type of regulator it must be checked regularly by a competent gas technician, since if it fails, it could allow gas at too high a pressure to enter the system.

H  IS FOR
HEATERS
Most vans have space heaters in which the combustion chamber is sealed off from the living area. Hence, no living area oxygen is used, and the carbon monoxide produced during combustion is exhausted outside. Some heaters also have a blown-air option, where the warmed air is fed through ducts around the van by a 12V fan on the back of the heater. Often, the blown-air system incorporates heating elements – up to 2kW – for use when the van is connected to the mains. The number of controls will depend on the sophistication of the heater. Ignition is either push-button or electronic, and these days is incorporated in the temperature control dial, while the blown-air system is operated by a second control. Both are fitted on the top of the heater. If mains elements are fitted, there will be a wall-mounted control panel to enable the owner to set the required power – usually 500, 1000 or 2000 watts – and the desired room temperature. During hot summer days, the fan can be used to circulate cool air throughout the motorhome.

HIGH-TOP
Many van conversions are fitted with a glass reinforced plastic (GRP) high-top roof. This takes the place of the original roof and affords good headroom. The moulding will be lined by the manufacturer to reduce heat loss and the chance of surface condensation forming on the inside. Small windows are often fitted in the sides of a high-top roof as well.

I  IS FOR
INSTABILITY
A poorly loaded motorhome will not ride well on the road. Heavy items in roof lockers are a recipe for body roll on mini-roundabouts and tight bends. Incorrectly inflated tyres are another contributor to poor road manners; and so are springs which are getting tired. So the vehicle itself must be in good condition and its owner aware of the need to load up wisely.

INSURANCE
Different policies offer differing benefits. Some cater for elderly owners and the underwriter is aware of their cautious driving styles. Others offer policies with discounts for low annual mileages. A few companies will insure self-built motorhomes whereas the majority are only concerned with professionally built models. Windscreen cover, foreign use cover, coupled trailer cover and a host of other elements need checking. So read policy descriptions with care.

INTERIORS
Motorhomes more than any other leisure vehicle offer remarkably contrasting designs inside. Some models are noted for their ornate interiors, florid fabrics, velvet pelmets, plush curtains and fully fitted carpets. For some that’s home from home: for others it’s grandma’s parlour on wheels. Then there are contemporary designs with plain colours, plastic laminates, easy-clean surfaces and vinyl floor covering. That’s a practicable style for active users but a bland, clinical minimalism for others. And herein lies one of the strengths of modern motorhomes. There are styles to suit people of all interests, all ages and all tastes.

J  IS FOR
JACKS
On nearly all European motorhomes, you need a portable jack in order to change a wheel. But you need more than that. No less important is knowing where you can position a jack without damaging the chassis. In a panel van conversion, the owner’s manual should provide this important advice. However, on a coachbuilt model, you mustn’t forget that a vehicle manufacturer’s original chassis is more likely to offer a few more acceptable jacking points than a lightweight chassis from, say, AL-KO Kober. More different, of course, are the chassis used on American RVs and some have hydraulic jacks installed as part of the undergear. That’s a provision on a totally different scale.