Diary Of An ADI

A Driving Instructor's Blog

Doner Kebab meat being slicedI first wrote this in 2017, but it’s had a run of hits lately. And I’m just making another batch, so an update seemed in order.

I like cooking, and I especially like to be able to reproduce food that I would normally end up paying an arm and a leg for if I went out and bought it from a restaurant or takeaway. I can make curry that tastes almost identical to those you get from an Indian Takeaway, and I can make pizzas which are also identical to takeaway ones.

Doner Kebabs (or ‘gyros’ if you’re in the USA) were always on my ‘to do’ list, but my previous attempts weren’t successful. Membership of various local cash & carry outlets means that I have access to the kinds of things you wouldn’t find on supermarket shelves, and I’ve seriously considered buying a whole doner leg (that’s one of those big things that slowly turn around in front of the grill at the kebab shop). If I’d have been stupid enough to do it, God only knows what I’d have done with 10kg of cooked doner meat – and yes, even the thought of buying a proper doner grill passed through my mind more than once. But genuine satisfaction could only come from being able to make doner meat from scratch.

The few goes I had were a hell of a palaver. It was all about mincing lamb breast twice, forming patties, pushing them inside an empty tin can, cooking it, then using a blow torch whilst turning the mini-doner leg on a fork and slicing layers off. Even the pictures that accompanied one of the recipes I tried (and note that the flavour of this was very good, if you’re wanting to make your own seasoning mix) showed that the final slices of meat were coarser-textured and nothing like a proper slice of doner meat. That’s how it turned out for me – the taste was pretty much spot-on, but the cooked meat was crumbly and had no ‘bite’ to it (and frankly, I wan’t that interested in farting around with a mini-doner leg, I just wanted the meat) The worded version of that same recipe suggested that commercial preparations ‘probably’ use transglutaminase – or meat glue – to hold the texture. That sounded somewhat plausible and I’d planned on trying it, when out of the blue the answer came from… bacon.

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Why bacon, you ask? Well, I had started curing my own bacon and I needed some curing salt. Whilst searching, I came across Surfy’s Home Curing website as a source. While browsing Surfy’s site I noticed that he also sold Doner Kebab Seasoning, and with my previous failed attempts in mind, I asked a few questions about the texture problem I’d experienced. That’s where the key piece of information came from: temperature.

In a nutshell, the most critical part to getting the texture right when making doner kebab meat is the temperature you do the mixing at. It has to be very, very cold, almost freezing – but not quite.

I can vouch for Surfy’s Kebab Seasoning, but you can get other brands. Some of them are commercial mixes so they should be fine.

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Making Doner Kebab Meat

Surfy’s Kebab Seasoning, comes with a handy recipe for doner meat. The recipe is so simple that I couldn’t believe it was going to work, but I decided to give it a go exactly as it was written to see what happened.

I bought two 500g packs of lamb mince from Asda and stuck them in the freezer along with a bowl of water. When the water had just started to freeze (therefore acting as a crude thermometer), I threw the mince into my Kenwood Chef fitted with the K blade, added 50g of the kebab seasoning, and mixed on a medium-high speed until it became sticky and of a uniform texture (just like pink bread dough, in fact). Then I added 50g of the ice-water and mixed for a minute more, also on medium-high speed. Apart from the hour or so in the freezer beforehand, it took less than 10 minutes to produce the meat mixture in accordance with Surfy’s Recipe.

As I said above, I wasn’t in the least interested in producing a weird shape I’d have difficulty cooking and handling, so I packed the mixture firmly into a non-stick loaf tin by hand. Rather than just roast it, I decided to use a crude bain-marie, so I placed the loaf tin inside another tin and half filled that with boiling water and place it in a pre-heated oven at Gas Mark 4. Using my Meater probe (any thermometer will do), I let it cook until the inside temperature reached above 75°C. Once removed from the oven, I drained off the rendered fat and let it cool a little.Slab of cooked DIY kebab meat

As soon as I cut into it I could immediately tell that I’d cracked the texture problem. It was firm and held together perfectly. And when I tasted it, it was identical to shop-bought kebab meat in both taste, smell, and texture. Once it was completely cool, I used my bacon slicer to slice it up into strips. The cooked loaf was about 220mm x 110mm x 65mm (i.e. slices were about 2½ inches wide).Slices of cooked kebab meat ready for reheating or freezing

I rolled the strips between parchment paper so that I could remove as many as I needed, and froze the roll for future use.

Making The Actual Kebabs

Re-heating can be done under the grill, in a pan, or in the microwave. Just don’t do it for too long, otherwise the strips dry out (though you might prefer your doner meat that way). Personally, I like mine juicy, so 30 seconds or so in the microwave gives you perfect moist strips.

I’ve typically like my kebabs on Pitta Bread, but I always find it a bit hit-and-miss over whether a pitta will puff up or not. Recently, Asda has started selling Naan Wraps, and these are absolutely perfect. They’re now my preferred bread for kebabs (until Asda stops doing them, as is their wont).

One of my kebabs will therefore be a naan wrap, 3 or 4 slices of meat with my favourite sweet chilli sauce on top, then finely sliced red and white cabbage, onions, peppers (that’s my own addition), onions (red or white), tomatoes, cucumber, and Iceberg lettuce. You can put as many vegetables on it as you like. And that’s it.


I estimate that 1kg of lamb mince produces enough doner meat for up to ten kebabs – admittedly, perhaps not if you put the same amount of meat in you get from takeaways, but that’s probably a good thing because they are usually into pig-out territory anyway. At £8 per kg of mince, plus £0.60 for the seasoning, each serving of meat comes to about 85p. With all the other stuff, you’re looking at well under £1.50 per kebab – and it’s a full, healthy meal. You’d be looking at £5-£6 in a takeaway, and a lot more fat.


No one is ever quite sure what goes into commercial kebab meat. Even taking away concerns about the actual animal the meat in them comes from, they are loaded with additional fats (often trans fats) that have been added eat during manufacture. And since we’re looking at commercial production, chemical additives (sodium phosphate, in particular) are used, quite possibly along with synthetic flavourings in some cases. In short, you simply don’t know what you’re eating – just that you’re eating a lot of it (and you know you shouldn’t).

The only fat in this homemade meat comes from the lamb. The Asda lamb I bought contains less than 20% fat in the first place, and a lot of that is rendered out during cooking (which I pour away). It contains nothing except lamb and the seasoning.

I estimate that each homemade kebab weighs in at no more than 800 calories, even on a large naan (less on one of the Asda wraps I mentioned). On a pitta it’s closer to 500 calories. Indeed, the majority of the calories come from the bread and not the meat. It’s no more than a typical meal, and a lot healthier since it contains a lot of vegetables.

If you were on a 2,000 calorie diet, you could have up to three of these as your main meal without any worries. A shop-bought kebab, on the other hand, could contain the full 2,000 calories in one go.

Could you cook it over a grill like they do in the shops?

Yes, of course. As long as you made sure it was properly cooked as you sliced it, the raw mixture could be formed on a spit, and rotated over or in front of an open flame to cook it. I haven’t tried it and have no desire to, but if you packed it tightly and then chilled it I’m sure it would be firm enough to put on a spit. Come to think of it, that’s how a takeaway I used to use many years ago did it – I watched him one day taking handfuls of meat mix out of a bowl, forming them into discs, and then throwing them on to the skewer of the large spit as he formed the ‘elephant leg’ a layer at a time. If you really, really want to go for the poseur approach, you can buy devices to do it.

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I’m not quite crazy enough to go this far, though I am crazy enough to have been tempted. Sorely tempted, I assure you.

Can you freeze cooked doner meat?

The recipe given above is cooked from fresh ingredients. If it is frozen quickly afterwards it’s fine for freezing. Just don’t let it hang around too long before you slice and freeze it. And never re-freeze it once thawed.

Freezing doner meat you bought in a kebab from a shop is definitely out. It was probably frozen to begin with, and you have no idea what the hygiene standards were when you were sold it. You don’t need me to tell you what the insides of kebab shops are like, and eating fresh from them is OK, but leaving it around for too long is asking for trouble.

Is it possible to buy doner meat already made?

Yes. Some cash & carry outlets sell tubs of cooked meat frozen. You can buy it in some supermarkets in smaller packs. It tastes fine, but it is relatively expensive compared with DIY.

What gives doner kebab meat its texture?

It’s all in the preparation. The meat has to have about 20-25% fat and it has to be very cold – almost freezing – when you do the mixing so that it can emulsify (i.e. the meat and fat are no longer separate). When you press it down into a mould or tray and cook it as described above, the texture is just right – not at all crumbly, but firm with a definite bite to it.


Kill Bill: Vol 1 - posterDuring the lockdown I was watching films and TV shows I’d downloaded and ripped from DVD. I prefer to watch videos on my TV rather than my computer most of the time, and I use Plex as my preferred media server.

Plex is great, but I was suffering from buffering problems when using it. A lot of others have, too, and from what I have deduced it isn’t specifically (or just) a problem with Plex, but partly with Wi-Fi. It is worse when you are watching 4K content, for example, because Wi-Fi just can’t handle the bandwidth in some cases – especially when you have several devices using it at once. Buffering was driving me insane to the extent that I tried various alternatives to Plex. But nothing comes even close to it for features and ease of use. The last straw was when I was watching Kill Bill: Vol 1 for the umpteenth time, it kept stopping during the fight scenes when a lot was happening and the required bandwidth went up.

How Plex works is this. You install Plex Server on your chosen computer, and tell it where your movies and other stuff is stored. Then you install Plex client on your smart TV, Firestick, or whatever, link it to your server, and you can watch your shows whenever you like. Most people will opt for Wi-Fi networking to eliminate the need for wires trailing everywhere in order to connect their devices.

I’m a bit of a Wi-Fi sceptic. I mean, it’s fine when it works, but it often doesn’t. The other thing is that my internet connection is 600Mbps, but there is no way Wi-Fi can match that. It doesn’t matter in most cases – when connecting devices to the network for updates and so on – but it does if you actually need the fastest connection for something. Or if you’re trying to stream high-bandwidth films.

Last year, I bought an Ethernet adapter for my Firestick (from where I run Plex client) and connected it directly to my router. Buffering disappeared, so that was one problem more or less resolved.

However, a related issue was to do with storage. My PC, which I built myself just over a year ago, has two 1TB SSDs and one 2TB SSD. You’d think that 4TB would be enough space (I also have a spare 2TB SSD which I was planning to install), but I then realised I’d got around 3TB of movies and TV shows, with the entire box set of Frasier still to rip at some point, which will add probably another 2TB. SSD is an expensive way of increasing storage, and you still have the potential for a disk failure eventually, which means you lose everything on it (I got stung with that previously when we had a power cut that blew my last self-built machine). I needed something bigger and safer

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Now, I said I was a bit of a Wi-Fi sceptic, but I am a full-on ‘cloud’ sceptic. The idea of trusting all of your files to the cloud just doesn’t make sense to me. For one thing, it is expensive if you want a lot of storage (Amazon used to offer an unlimited cloud service, but it was being abused and they stopped it). And unless you pay for it (I assume), the cloud is sloooooow. I have a 1TB OneDrive account through my Office365 subscription and if I want to download a movie file from it I can assure you it isn’t downloaded at anywhere near to my 600Mbps internet connection speed. Uploading such files is worse because of the massive difference in upload speeds even with your ISP.  Then you need to factor in how fast your cloud is going to let to have the file – usually at about a tenth of that speed if you’re lucky – and it’s a nightmare. The download also seems to be proportional to how urgently you need it – if you’re desperate, you can virtually guarantee an outage somewhere or download error.

I’d been considering a NAS (Network Attached Storage) solution for a while. This is just a storage system you maintain yourself. I wanted to be able to store and access large files immediately – not tomorrow, after several failed tries. I also wanted to be able to work on them where they were stored – just like on your PC – and not with the extra steps of having to download them first, altering them, then having to upload them again. A NAS is exactly what it says – a disk storage system that is on your network, and not someone else’s.Synology DS1821+ NAS

Be aware that a NAS is not a cheap solution to begin with. Once you have it, it is virtually free, but a NAS enclosure starts at around £150, and disks to populate it at around £70 each. I opted for the Synology DS1821+ DiskStation 8-bay, which costs just under £1,000.

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You can set up a NAS using single disk drives, where each drive acts just like one in your computer. However, if the drive fails at any point, all your data are lost. I’ve been bitten with that before, as I mentioned. I wanted better security, so I wanted a RAID system – where you use multiple disks to either ‘stripe’ the data or ‘mirror’ it. This is where you have to trade off the level of security/safety against reduced capacity. For example, if you simply ‘mirror’ across two disks (RAID 1), then you might have two 1TB disks which have the exact same data on them, which is secure if one fails, but you only have 1TB capacity, even though you have two 1TB disks. To cut the story short, I wanted RAID 5, which needs at least three disks to ‘stripe’ the data, but which gives you the capacity of two of them whilst still retaining all data if any one of the three fails. Weighing up the prices of the available disk drives against my likely storage requirements I bought three 12TB HDDs at a cost of £270 each. This would give me 24TB of storage, with the additional data security I wanted.

A NAS is essentially a PC – a computer. It runs its own operating system, which on the Synology is called DiskStation Manager. It is just a black box you put on your desk, and you access it through a web interface in your browser once you’ve connected it to your network via the router. Installing the hard drives is easy, and once you’ve plugged in the necessary cables and turned it on, finding it it and adding it to your network is also easy. Various guides take you through setting up your chosen RAID configuration, and that is very simple too. After that, all you have to do is map your drive from Windows on your PC and you can use it.

An additional detail that cropped up was when I accidentally pulled out the plug for the NAS one time, and the system reported an unexpected shutdown after rebooting. It also warned that this could lead to data loss and disk corruption – a major alarm bell for me – so I got a UPS (Uninterruptible Power Supply) to prevent that happening again. A UPS is a battery backup system, and I already have one for my PC after that damned power cut blew all my disks. I chose an APC unit which has a data link that the NAS can interface with and perform a controlled shutdown if the power fails and the battery runs out. It cost £110.

I now have a neat system where I have 24TB of storage that I can access at network speeds. I can access it as a normal ‘disk drive’ from my PC, or via the internet on my laptop or smartphone if I wish, wherever I am. It is connected by cable to my Firestick, so there’s absolutely no buffering. My data is more secure than if I was operating on single drives (and I’ve been caught out with that previously, as I mentioned). I can expand if I need to. It is my own ‘cloud’.

I have installed Plex server on the NAS, and linked Plex client on the Firestick to it, and there is no buffering whatsoever. All my content is now on the NAS. And if I want to work on a file, it is just on another drive which I can access whenever I want. No more download, fiddle around, then upload.


The Chillmax AirI wrote this in the very hot summer of 2019, but each year around spring time adverts start appearing involving these ‘revolutionary no-install air conditioners’.

Be aware that these devices do not work to anything like the levels claimed. The original article follows.

Early in July 2019, I saw the Chillmax Air advertised on TV in one of those shouty ads. Then, the same evening, I was shopping in Asda and saw it on display. I am an idiot for things like this, and bought it on impulse so I could test whether it worked or not.

As a chemist, I know that in order to cool a large space effectively you’re going to need something with a big fan and a special refrigerant. In practical terms, that means a fairly bulky device with a motor-driven compressor, a closed radiator for the refrigerant to pass through, a fan to suck air in and blow it across the radiator, and a wide exhaust pipe through the wall or window to get rid of the ‘removed heat’. In some cases, you also need to collect or drain the condensed water that comes out of the air as it cools. A typical proper air conditioner for a small or medium-sized room will be about the size of bedside cabinet. The Chillmax Air is not much bigger than six CD cases glued into a cube.

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If you’ve used a normal desk fan you will know that you only feel cooler if you’re sweating a bit. That’s because the fan evaporates your sweat as it pushes air over it, and that evaporation is accompanied by a small cooling effect – it’s called ‘evaporative cooling’. If you’re not sweating, you don’t feel the effect. Conversely, if the surrounding air is very humid, then no matter how powerful your fan is, you will feel little or no cooling because sweat can only evaporate if the air has capacity to hold additional moisture (I’ll explain that a bit more later, because it’s what determines whether the Chillmax is any good).

As an aside, many liquids exhibit the evaporative cooling effect. In the case of diethyl ether (the stuff they used to use as an anaesthetic), if you force it to evaporate very quickly you can even freeze water (if you do it properly). However, ether is both highly flammable and toxic, so apart from demonstrating it in the school lab (where I remember it from, partly due to the massive headache the fumes gave me), it doesn’t have much practical application these days. Early refrigerators used it, which was spectacularly dangerous.

The Chillmax Air uses the evaporative cooling effect of water, and this is much less than with ether – similar to sweat, in fact. The unit consists of a reservoir at the top, which you fill with normal tap water, and this drips down on to a radiator unit which has ten sideways-stacked fibre panels in it through which a fan blows air. The water evaporates from the fibre panels, and the evaporatively cooled air comes out through the front grille. According to the marketing spiel on the TV ads, you’d be forgiven for thinking you’re going to get frostbite if you sit too close. I knew this wasn’t going to happen, but I wanted to know just how effective the Chillmax was.

When I first set it up and turned it on, the first thing I noticed was that the fan is quite powerful, so you get a good flow of air directed at you – but note that that it’s only a 5″ computer fan, so it can’t beat a proper desk fan for air flow. The air did seem a little cooler compared with what my desk fan was blowing at me, but it also felt ‘softer’ – that’s very important, and I’ll explain later. But the big question was how much cooler was the exhaust air?

I fired up my trusty data logger and left it in front of my desk fan for 30 minutes for the control data. Then I moved it and suspended it in front of the Chillmax for the same period of time. This is what it recorded (the red line is where I moved it).

Chillmax - temperature log in hot and sticky conditionsThe ambient temperature where I ran the test was about 29ºC. The Chillmax brought this down by about 4ºC.

So, the Chillmax definitely cools the air that passes through it. Let’s work on the assumption that it would be able to get the same 4ºC drop no matter what the ambient temperature was. If your room is 38ºC, pulling it down to 34ºC still means it’s bloody hot. And also note that since the Chillmax is physically so small, the cooling is very localised – it won’t cool a room down, and you have to have it less than a metre from your face to feel anything.

Now, some people might be thinking that a 4ºC is better than nothing at all. And they’d be right if it was just a matter of temperature. But there’s more to it than that. I mentioned that the exhaust from the Chillmax felt ‘softer’. I knew what it was, but my data logger shows it in numbers.

These are is the data for relative humidity recorded at the same time as the temperature measurement, above (the red line is where I moved the logger). The humidity went up dramatically – a jump of about 30%RH.

Chillmax - RH log in hot and sticky conditionsAs I’ve already explained, the Chillmax works by evaporating water on fibrous panels by forcing air across them. That water has got to go somewhere, and in this case it comes out as vapour in the cooled air. In the right light, you can actually see it – it’s essentially fog. And just like when it’s foggy outside, and everywhere gets damp, this vapour can condense on surfaces. My data logger collected some and began to drip during the test, and I have since discovered that it also condenses on the front grille and can drip periodically, so you’d need to be careful what you had underneath it if you placed it on a shelf. The fan is quite powerful enough to project the drips forward slightly when they drop.

The ambient humidity in the room where I did the test was about 44%RH. The Chillmax sent that up to over 70%RH.

It’s this elevation of the humidity of the cooled air which really brings into question whether the Chillmax is worth the investment. You’re probably aware that you can have a hot summer day in the high 20s where it is pleasant and comfortable, but a cooler and overcast day might be horribly sticky – or muggy. That’s because of the humidity, or water vapour in the air.

The amount of water vapour that air can hold varies with the temperature. Once you reach the maximum, any extra vapour condenses out as a liquid – misted up windows, dampness, even drips and pools of moisture on window sills or under lamp posts. Cold air can only hold a small amount of moisture before condensation occurs, but hot air can carry much more (think ‘sauna’). Although ‘humidity’ technically refers to the amount of water in the air, the figure most people are referring to when they say it is relative humidity. This is the amount of moisture in the air expressed as a percentage of the maximum amount it could hold at that temperature, hence the units %RH. It’s a very complicated subject, but the important factor for us here is that when it is warm or hot, higher relative humidity is uncomfortable. Indeed, you may have seen weather forecasts where they give the actual temperature and the ‘feels like’ equivalent – that’s a reference to the ‘Heat Index’, which takes into account the effect of the %RH. Here’s a graphical chart for that.

Heat Index - graphical representationAs an example, if the air temperature is 30ºC and 50%RH, it will feel like 31ºC, but if the humidity goes up to 80%RH, then it will feel like 38ºC – even though the thermometer still tells you it’s 30ºC.

Another example. If the air temperature is 35ºC, at 50%RH it will feel like 41ºC, but send the humidity up to 80%RH and it’ll feel like 57ºC – even though the thermometer still reads 35ºC.

The calculation for this is complex (you should see how long my Excel formula for it is). It is non-linear, and the increase in ‘feels like’ is greater at higher temperatures. It also contains an element of opinion/perception, which is why there’s no point using numbers above about 60ºC. But the ‘Heat Index’ is what forecasters use. Incidentally, the official health designations for the colours are: yellow – caution; amber – extreme caution; orange – danger; and red – extreme danger. Vulnerable people need to take these into consideration before going out in hot weather.

However, this is where the problems come in for the Chillmax and similar devices. If it’s 35ºC and 40%RH, it’ll feel like 37ºC. Cool the air to 31ºC but send the humidity up to 80%RH, and it’ll feel like 41ºC. So it’s actually hotter in terms of comfort. Do the same comparison when the surrounding temperature is 38ºC, and the ‘feels like’ goes from 43ºC to over 50ºC!

At lower temperatures the Chillmax will produce a slight net cooling effect. But if the air temperature is above about 30ºC (and 50%RH) – which isn’t excessively hot or humid to start with – it’ll actually make you feel warmer. And if it is already humid outside, you’ll feel hotter still.

Proper air conditioners remove water from the air they cool. This removal of moisture is why the air from proper air conditioners feels crisp, as opposed to the ‘softness’ of moist air. The Chillmax does the opposite of normal A/Cs, and adds moisture.

Aesthetically speaking, the Chillmax is a cube – more or less – about 15cm along each side. There are two buttons on the top rear, one which changes the fan speed to one of three settings (or off), with a blue LED for each, and another button that turns the night light on or off. There’s a flap on the top front through which you add the water. The radiator system is a plastic-framed insert which you access by pulling the front grille out. It slots in and out easily. You can’t officially replace the fibre inserts in the radiator, but you can buy the whole radiator assembly from JML for £15. My only major gripe is the power cable. The jack plug that goes into the Chillmax is quite stubby and doesn’t go into the socket very far, so it is easy to dislodge it. However, the cable itself is quite long, and the  mains plug is a moulded UK type.

JML claims the Chillmax can run for up to 10 hours per fill, but this is likely on the lowest of the three fan speeds, since on top speed it runs out in less than three hours.  JML sells the humidification as a positive without relating it to the comfort relationship between temperature and %RH, but note what I said above. If you want to cool down in humid weather, it isn’t just the temperature that needs to come down.

Does it really work?

It does cool the air by a few degrees, so in that sense it works. However, it also sends the humidity up, and in most cases that actually makes you feel hotter and more uncomfortable. In that sense, it doesn’t work.

Will it cool more if I use ice water?

No. Evaporative coolers are not influenced significantly by the temperature of the water used in them. The temperature of the air that comes out depends on the temperature (and humidity) of the air going in, and the science of evaporation. Only this evaporation results in the cooling effect observed.

Will it cool more if I put the filter in the freezer?

It might – while you’re blowing air over ice. But once they defrost, which will happen in a few minutes in the temperatures you’ll likely be experiencing, then no. You’ll also have more condensate to deal with from the melted ice pouring out of the front grille.

You may see reviews on Amazon claiming that freezing the filters (or using ice cubes in the water tank) does give cooler air. Trust me – apart from what I just said about blowing air over ice, it doesn’t. Science is involved, and evaporative cooling doesn’t work like that.

Can I use it to cool my PC?

Someone found this article on the search term “jml chillmax air for pc cooling”. No. Blowing damp air into your PC would be dangerous, potentially expensive, and would only gain you 4ºC at best.

Can you get larger versions?

You can certainly get larger evaporative coolers, though not the Chillmax specifically. The working principle is that the larger the surface area of water, and the greater the airflow over that water, then the greater will be the possible drop in temperature at the front end. However, cooling effectiveness is influenced greatly by the RH of the air going in.

If the air is very dry, then a large evaporative cooler might be able to drop inlet air at 30ºC down by as much as 10ºC. However, if the inlet air is very humid, the temperature drop could be as little as 1ºC. In the UK, the realistic temperature drop you could expect on a non-humid day for a large cooler would be around 5-6ºC, but on a sticky day you’d only get about a 3ºC drop.

Suppliers of these devices say that they need good ventilation or extraction, and I would imagine that’s so the humid air can escape. If you’re evaporating more water to get better cooling on larger devices, you’re also producing a lot more water vapour. Be careful if you read any of the reviews – people may have noticed cooling in already cooler conditions, but trust me – if it’s very warm and humid, you will not notice any effect.

People say it works

Be careful when you read those one-line reviews. If you test it when it’s only 20ºC outside – as many of these people have – then yes, it blows noticeably cooler air at you. But science is involved, and at temperatures above about 28-30ºC you’ll actually feel hotter. The fact that it increases humidity is the key factor. Remember that the reason you even found this article was probably because it’s over 30ºC outside – the more above that it is, then the more hits I get.

So, does the Chillmax work?

It cools the inlet air by several degrees. But it sends the humidity of that air up considerably, and this cancels out the benefits of the cooling effect when it is very hot. The ‘Heat Index’ is the key detail, as explained above.

Only the air being directed at you is cooler. Once that slightly cooler air has passed through warmer air, it’ll be close to ambient again. The device cannot cool down a room. It’s far too small for that.

Humidity can carry much further, though. So in a small room, you could easily increase the ‘ambient’ RH without any cooling at all, and that will make it feel even hotter. If it is already hot, the amount of water vapour the air can hold before reaching 100% RH will be substantial. The increased humidity of the outlet air does produce localised condensation, so you have to be careful to keep it away from electrical sockets where it might drip on them. The unit also contains a significant volume of water when full, so you don’t want to knock it over.

Should I buy one?

My advice is to buy a proper air conditioner (A/C). If anything costs under £100 it is not a proper A/C. However, it is possible some people might find the minor cooling effect and increased humidity of the Chillmax (and similar devices) beneficial, so the choice is yours. But for real cooling and dehumidification when it is hot, it has to be a proper A/C.


Logic For DummiesI only wrote this at the beginning of May, but it’s already worth an update.

At the time when I first published it, a lot of instructors were complaining about the waiting time for driving tests. Several of my own had had rearranged tests assigned which were in June-August. I managed to book another at Watnall for July, but since then there has been nothing.

As I write this update, the online booking service goes as far as 14 November, and there is not a single available test at any of the three Nottingham test centres, and it has been like that for weeks now. That’s a five and half month wait at the very least – which is already an increase of a couple of months compared to what it was in March (when I booked the Watnall test, there were a lot available, and July was just over four months away). I warned it would get worse, but I don’t think we’ve seen just how much worse yet.

That’s because there is another likely issue that ADIs haven’t cottoned on to. At the moment, most of those booking their tests were pretty much test-ready last March (or certainly, at the end of September/October 2020), and it is mainly they who are taking booking slots right now. But the thousands of new learners who have only recently started lessons are all going to become test-ready.

I might end up being wrong, but logically we will end up with all those new learners wanting to be booking tests at roughly the same time, and certainly over roughly the same period of time. My guess (prediction) is that that is going to send the waiting time through the roof. And don’t forget that this is on top of all those who have failed their rearranged tests since for whatever reasons. Heck, the pass rate will still be about 50:50 at best, so they’re going to have to book further re-tests.

I had one of those ‘whatever reasons’ recently. His rearranged test had been set for June, but he got a cancellation for the following week sometime in April and went in his own car. He’d only done six hours with me last October, but was doing a lot of private practice with his mum. He failed, and was initially looking at September for his next test – though he got anther cancellation, this time for July. I’d warned him about cancellations likely being short notice, too, but he wouldn’t listen.

DVSA has put on extra tests and examiners, and that will obviously help a little. But they would need hundreds of tests and examiners to manage what I believe is going to happen in a few months time.

Ironically, instructors desperate to fill their diaries to overflowing are making it potentially worse – for themselves, as well as everyone else. They are rushing pupils through for their own financial benefit, but tests are virtually impossible to get and are typically nearly six months away if you manage one. Many ADIs are moaning about pupils and parents asking if they can book the test after the first lesson, and refusing to do it. What happens when those pupils reach test standard and then have a huge wait ahead of them for the test you eventually allowed them to book? They won’t be at all happy.

I am trying to plan ahead. I am advising even new starters with no experience to get their theory test done as soon as possible, and then we will book their practical test no matter what (if we can find one), because six months or more is plenty of time to learn how to drive for most people. I stress they will have to move it if they aren’t ready, and we are not going to pick a cancellation date if it is less than three months away. I am trying to help them make the best out of a bad situation. I have also made it absolutely clear that if they are near to test standard and their test is still months away, we will cut right back or even stop lessons altogether so they don’t spend more money than necessary.

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The blog article about How to do Roundabouts remains popular (and, judging from feedback I receive, very useful to many). One question which crops up again and again is to do with positioning on roundabouts. At the time I wrote this original article, it was being fuelled by nonsense from IAM, and and readily picked up by ADIs who have ideas above their station.The Highway Code roundabouts image

The Highway Code shows this picture (above) and the accompanying text says:

Rule 186

Signals and position. When taking the first exit to the left, unless signs or markings indicate otherwise

  • signal left and approach in the left-hand lane
  • keep to the left on the roundabout and continue signalling left to leave.When taking an exit to the right or going full circle, unless signs or markings indicate otherwise
  • signal right and approach in the right-hand lane
  • keep to the right on the roundabout until you need to change lanes to exit the roundabout
  • signal left after you have passed the exit before the one you want.When taking any intermediate exit, unless signs or markings indicate otherwise
  • select the appropriate lane on approach to and on the roundabout
  • you should not normally need to signal on approach
  • stay in this lane until you need to alter course to exit the roundabout
  • signal left after you have passed the exit before the one you want.When there are more than three lanes at the entrance to a roundabout, use the most appropriate lane on approach and through it.

The underlining is mine, for emphasis. The Highway Code – both image and text – is crystal clear about staying in lane on roundabouts. It says nothing about ‘straight-lining’ or advanced (imagined or otherwise) police pursuit techniques. That’s because 99.9% of drivers shouldn’t be trying those things on normal British roads (and I include every single member of IAM in that 99.9%).

Then we come to Driving: The Essential Skills (TES, latest edition). This is effectively the syllabus that all driving instructors should be teaching in accordance with, with no exceptions that I can immediately think of. It says:

Procedure when entering/leaving a roundabout

Adopt the following procedure unless road signs or markings indicate otherwise.

Going left

  • Indicate left as you approach.
  • Approach in the left-hand lane.
  • Keep to that lane on the roundabout.
  • Maintain a left turn signal through the roundabout.

Going ahead

  • No signal necessary on approach.
  • Approach in the left-hand lane. If you can’t use the left-hand lane (because, for example, it’s blocked), use the lane next to it.
  • Keep to the selected lane on the roundabout.
  • Check your mirrors, especially the nearside exterior mirror.
  • Indicate left after you’ve passed the exit just before the one you intend to take.

Going right or full-circle

  • Indicate right as you approach.
  • Approach in the right-hand lane
  • Keep to that lane and maintain the signal on the roundabout.
  • Check your mirrors, especially the nearside exterior mirror.
  • Indicate left after you’ve passed the exit just before the one you intend to take.

Again, the underlining is mine, for emphasis. TES is also crystal clear about what is expected of drivers using roundabouts. It also uses the same image found in the Highway Code.

Even if you open a copy of ‘Roadcraft – The Police Driver’s Handbook’ you will not find any explicit recommendation that this procedure is to be ignored and replaced by ‘straight-lining’. It’s only when you start searching various ‘advanced driving’ forums (where people have names like ‘Super Scooby’ as tribute to the fact that they drive a Subaru pratmobile) that the concept of ‘straight-lining’ roundabouts rears its head. The general attitude of the average piston head-cum-IAM-member is basically this (my translation):

Straight-lining is not recommended by any authority, and you will not find it written down anywhere. The police recommend using lane discipline at all times except when on an emergency call. HOWEVER… because we class ourselves as advanced drivers, if WE feel it is safe to straight-line a roundabout then that’s perfectly OK.

Seriously, that is exactly what it boils down to. At the time I first wrote this, IAM was simply up to one of its periodic self-promotion exercises.

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Is it OK to straight-line a roundabout?

If there are marked lanes, you should use the marked lanes! You have absolutely no reason to do it any other way, since following the lanes will be the safest line through – that’s why they’re there. You have no need whatsoever to gain a fraction of a second advantage by ‘straight-lining’ as opposed to following the lanes. At best, you will manage to overtake a couple of other drivers who will then laugh at you when they catch up at the next set of lights. And the set after. And so on.

If the roundabout itself is unmarked, then you should use implied lane markings as suggested in the Highway Code diagram shown above. For example, if you have a two-lane dual carriageway feeding a roundabout – and there are no lane markings suggesting otherwise – then that implies that the roundabout also has two lanes. Implied markings extend to most roundabouts where two cars can proceed on to them at the same time, even if there is only a single marked lane on approach. It also applies to most of those which are wide enough to accommodate two cars side by side. The implied markings are governed by the widest feed road (i.e. it doesn’t matter if you’re entering from a single-track road, if the roundabout also has a six-lane dual carriageway feeding it, then it will have six lanes at some point!)

Will I fail my test if I straight-line a roundabout?

If it is clearly marked with lanes and you go careering across several or them and then back over again, yes. If a lane is clearly marked A60, for example, and another A52, if you attempt to take either the A60 or the A52 using the wrong lane you will be nailed for it. And you deserve to be.

If the lanes are implied then examiners often use a little common sense. Remember that learners and new drivers are, by definition, not experienced. For some, even driving in a straight line and checking their mirrors at the same time can be a major challenge, and although most learners are not quite that bad (though they do exist), they are far from being perfect drivers and their awareness skills are not fully formed. Therefore, if a learner on test doesn’t stay in lane – whether marked or implied – on a roundabout, almost without exception it is because they didn’t realise they were doing it and it is a serious error. This is especially true if there’s another road user there, and the examiners will mark it accordingly.

I have listened in on several test debriefs where someone has failed for doing precisely this, and the explanation has gone roughly as follows:

You approached the [implied markings] roundabout in the left-hand lane [of a two-lane dual carriageway]. As you moved on to it, you moved across towards the centre – which is OK – but you didn’t check your mirror to see if there was anyone coming up behind or in your blind spot. So that’s why I’ve had to fail you.

Personally, I hate this explanation, because it implies that the driver did it on purpose and just didn’t check. But I know they didn’t have a clue what he was talking about (I had to show one of them the dashcam footage on at least one occasion so they understood both where and what had happened). It was lazy positioning and no road markings – not intentional ‘straight-lining’.

It would be far simpler (and safer) just to learn to bloody stay in lane and keep out of harm’s way.

One final point. You might get away with lazy positioning once or twice if you’re lucky. Keep doing it and you will be marked down, because it is a fault.

Where can I read up on straight-lining?

You can’t – not unless you just want inaccurate and unofficial nonsense from middle-aged boy racers. The whole concept of ‘straight-lining’ is completely absent from any authoritative published material. DVSA expects good lane discipline on roundabouts.

I was taught to straight-line in the police/military

The only real purpose for ‘straight-lining’ is to gain advantage – either getting past someone, or saving fractions of a second. For the police on a call, that makes sense. I’m not convinced on the reasons for the military teaching it unless it, too, was for pursuit or reasons of timing (or possibly so the cargo doesn’t tip over). There is absolutely no reason for a normal driver (even if they are an ADI) doing it except to show off or be different.

I teach my pupils to straight-line if it’s safe

Then you’re not teaching them properly, because it isn’t what DVSA is expecting you to do. You are expected to teach them lane discipline, not some smart-arsed ideas from an online driving group that thinks it is ‘advanced’.

Learners (and new drivers) do not have the experience to be able to reliably check that it is safe to ‘straight-line’ and deal with everything else that might be going on. If they get it wrong when they’re out on their own it would be a disaster. Many of them can’t follow lanes because they don’t even know the lanes are there, and they should be taught how to do it properly first. When they’ve passed, it’s then up to them whether or not they turn into smart-arse know-it-alls, but they shouldn’t be taught to be smart-arse know-it-alls when they don’t even know the basics.

Straight-lining is an advanced driving skill that it is useful for learners to know

No it isn’t. It’s only an ‘advanced skill’ to a small number of anoraks, and apart from making the statement ‘look what a prat I am’ it serves absolutely no useful purpose for normal drivers. It is used to overtake where you shouldn’t, or to gain pointless milliseconds that are lost at the next set of traffic lights.

On a larger roundabout, your road position is likely to be misleading if you’re ‘straight-lining’, and that means others could enter it as you swerve back over. The police get away with it because they have a siren and flashing blue lights – and even they occasionally have accidents because of it.

Learners should be taught to slow down and check properly at roundabouts, not to take risks.

How would the examiner view straight-lining?

It depends on the examiner. In the example I gave above, they often seem to assume it was deliberate but without the mirror checks. However, I know full well that it was because they hadn’t got a clue that there were lane positions to follow. On the other hand, I am pretty certain that if the roundabout had clearly marked and signed lanes, attempting to ‘straight-line’ one of those is not going to be seen as a positive unless you got very, very lucky. In most cases, even if the pupil managed to get into the correct lane eventually, it would go down as a ‘road signs/road markings’ fault for not choosing the correct lane. But add ‘observations’ on top when they do it and a serious fault is almost guaranteed.

Just don’t do it.

Teaching pupils to stay in lane isn’t teaching them safe driving for life

I’m afraid that it is. Learners are not experienced – experience is something they have to gain for themselves after they pass their tests. They need to have the safest basic skills on which to build that experience, and learning how to stay in lane and avoid conflicts is one of the best examples of that. New drivers who ‘straight-line’ nearly always do so because they either don’t know how to stay in lane, or simply want to go faster than everyone else. Those who ‘straight-line’ are usually also speeding.

I am a ‘safe driver’. I’ve been driving my whole adult life. And I use good lane discipline. The only time I usually have to take any sort of evasive action is when other people don’t use good lane discipline.


All the Es

This article was originally published in 2011, but I’ve updated it a couple of times since, and again in 2018 following a run of hits. It’s been popular on and off since, and has suddenly been swamped again in mid-2021.

The original article came about after watching an argument flare up on a forum concerning the 4Es. Basically, no one knew what they were, but they’d all done a quick search and were arguing their own interpretations of the first hit they’d come across on Google. It’s funny watching people trying to put each other down when none of them have a clue.

As an aside, I notice that some organisations have turned the 4Es into the 5Es. At least I guess it means they can have more meetings, do more flipcharts, and offer more consultation opportunities instead of getting on with some bloody work. I’ve even seen the 3Es out there somewhere. Talk about confusion!

One of the big problems trying to get to the bottom of what the 4Es are all about is that even the people apparently implementing them obfuscate things so much that they don’t have a clue, either. The best place to go for a serious explanation is America, and a public safety site for Nevada is probably the best I’ve seen.

Nevada gives them as:

  • engineering
  • enforcement
  • education
  • emergency response

The Wikipedia entry explains:

Accident prevention and improvement of traffic safety

This comprises education and information, above all following the “4 Es”: enforcement, education, engineering, encouragement/economy. The main goal is promoting safety by influencing and modifying behavior using legal, educational, vehicle- and road-specific measures; driver training, driving-instructor education, information on traffic issues, campaign design and marketing, effective enforcement.

You will note the slight difference with the fourth one, though if you think about it, Nevada has it covered with their version – and bear in mind that they actually use it.

“Engineering” means things like road design, lane markings, footpaths, and so on (design things with safety in mind). “Enforcement” means publicity, policing, and so on (remind people, and pull them up if they don’t comply). “Education” means giving out information, conducting campaigns, and so on for all users (pedestrians and drivers). “Emergency response” refers to maintaining a “first responder” system.

India has been looking into it, and they refer to:

…included engineering of safe roads, provision of emergency care, enforcement of traffic rules and regulations, the use of ITS for improving road safety, and the creation of an educational and awareness campaign for changing road user behaviour to improve road safety.

The same headings as Nevada. And the ITE – an international organisation – says:

Within the 4 E’s of transportation safety, “engineering” and “education” are two of the more traditional focuses for transportation engineers and planners. However, the importance of “enforcement” and “emergency responses” should not be understated, and both are critical elements of a successful roadway safety management program.

From a driving instructor’s point of view, the education part is the one they are going to be dealing with, though perhaps with a little enforcement thrown in.

Remember, though, that it is the dog which wags the tail – not the other way round – and decent instructors (or anyone else acting responsibly) are covering their part automatically without having to worry about acronyms and the inevitable flipcharts and Powerpoint sessions. In the rat race, though, it all has to be documented and filed, so it is a much bigger – and more costly – job.


The Audi LaneHad a funny one this evening.

I was on a lesson with a pupil and we were driving through Mapperley. We stopped at lights and I pointed out to him that the lanes merged on the other side, and the Audi that had pulled alongside us was going to try and get in front at all costs. Which is precisely what it did.

Then we came to another set of lights at a junction, which had split into two lanes again. The Audi was in the left lane in front of us, and I pointed out to my pupil that it was going to turn left even though it wasn’t indicating. And it did.

My pupil was incredulous, and asked how I could possibly know that.

I explained that it was simple. It was an Audi. There were two lanes going ahead, and the right hand lane even had fewer cars in it than the left one did. There was positively no way any Audi driver would pass up a chance like that and use the left hand lane unless the driver actually had to be in it for some reason. I explained that in most cases, an Audi driver wanting to go straight ahead in that situation would choose the right hand lane by default, even if the left one was empty. The instinct among them is so strong that they can’t help themselves.

I also told my pupil that if he ever bought an Audi, I’d instantly be able to read his mind, too.


Chavs from Bulwell this time. Standard behaviour on the Nuthall roundabout.

The pupil was just driving home, and roundabouts are one of his current worries. Everything going smoothly, then these prats appear – at speed, in the wrong lane, across three lanes of traffic, and then they’re in the wrong lane anyway and cut across again at speed and head off the way we were going. Registration number MW16 ZUD.


And another one from last week. Heaven only knows what was going through their tiny minds.

In this case, it was a relatively new pupil who can also be a little jumpy. She wanted to be dropped off in the city centre, and at that time in the evening it is pretty quiet. The Mercedes (reg. no. FP20 JDZ) just stopped inexplicably at green traffic lights, and didn’t move even with us coming up behind. They weren’t even aware we were there until I sounded the horn.


And a couple of weeks ago, this one. Another elderly driver, though that’s not why I am posting these.

The pupil in question on this one is quite jumpy, and he just about shit himself when this happened. Then I just about shit myself when I saw a 3.5 tonne truck behind us slam his brakes on at the last moment.

Once more, the driver who emerged – and I couldn’t quite see his registration on the video, but it was FH14-something – likely has a clean driving licence, and would use that as evidence he wasn’t a danger on the roads. But he is a danger.

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