Log analysis

Test briquettes Normally I try to only use wood I’ve collected over the year and given time to season because why buy wood, when you can collect it for free. However the best laid plans don’t always work so in the past I have been forced to buy wood to burn, and properly kiln dried wood is lovely. However FaceBook has been bombarded me with adverts for various log substitutes so I thought I’d give them a try to see how well they perform. Now it should be noted this hasn’t been terribly scientific and the briquettes chosen were picked purely by the fact they got advertised at me (and two of them looked cool). From top to bottom there are bark briquettes, heat logs and coffee logs.

The first thing to consider is the price, the Bark briquettes if not bought as a a sample pack are about 60p a kilo, as are the heat logs, the coffee logs are more expensive come in at a pound a kilo ( probably because I’ve not found anywhere doing them in bulk ). The bark briquettes and heat logs compare reasonably well to kiln dried logs which are (from some hasty Internet research) about 55 to 60p a kilo, though it’s harder to get a price per weight for actual wood as it’s normal sold by volume.

My experimental method was fairly simple, get my stove going as normal and once I had a bed of embers put in each of the log substitutes in turn and see how long they burn for keeping the chimney temperature at about the same level ( 300°F ) for each of them for the duration of the burn. Each of the pictures shows 2kg of the log substitute.

Coffee Logs

Coffee Logs I can’t help but think these are really rather cool, waste coffee grind compressed into logs to burn. However you can’t get them in bulk only in little 16 log (8 kg) paper bags, which isn’t really ideal for getting a whole load in once a year. They do smell lovely when you open the bag, assuming you like coffee of course. If you don’t like the smell of coffee you won’t want these in your house. However if you do like the smell of coffee you also won’t want these, because in no surprise at all when you burn them they smell like burnt coffee. This is not a nice smell, now I’ve got a nice efficient closed stove, so when the door is shut I can’t smell them, when I open the door to do anything I get a solid blast of acrid burnt coffee. If I had an open fire I’d hate these and probably wouldn’t be able to stay in the room whilst they burnt.

That said they do seem to live up to the claim made by Bio Bean:
“Each carbon neutral Coffee Log is made from the grounds of 25 cups of coffee and contains about 20% more energy than wood – meaning it burns hotter and for longer than wood.”. Using two logs (1Kg) I was able to hold my chimney temperature at around the 300°F mark for 45 minutes, which really isn’t bad going. I really want to like these, they’re clean to handle, light easily, burn well, but oh my god the smell of burning coffee when you open the stove.

Heat logs

Heat logs I must confess I got these mainly because I was getting a Bark Briquette sample at the same time so I thought why not. As I only got a sample pack the price per kilo was higher but for playing about that’s fine. These are tubes of compressed hard wood. As they come wrapped in bags of five storage and handling is easy though you’ll end up with a lot of plastic wrapping even if you order in bulk. As you might expect they’re clean and uniform and as promised they do burn well and generate a lot of heat to get the room up to temperature quickly. However as Lekto warn you they do expand whilst they’re burning, they pretty much double in size so they need to be broken up. I tried breaking them up as they expanded and really wouldn’t do that again as they can be quite firm, breaking them in half before putting them in the stove was a lot less fraught. I’m not convinced by the claim that they “produce very little ash“, less than a paper briquette certainly, and if you run your stove hot then the amount of ash isn’t too bad. However if you damp your stove down for a slower burn then you do end up with quite a lot of ash, they’re also really not the easiest things to add more fuel too once they have burned down as they don’t produce useful embers. As far as burn time goes I got about 90 minutes out of a single heat log (2Kg) at the same chimney temperate ( 300°F ) as previously. So a perfectly reasonable burn rate, but they did need more tending than the coffee logs to avoid being left with an excessive amount of ash, and you really couldn’t use them for a slow burn, but for getting a stove warm quickly they’re pretty good.

Bark Briquettes

Bark Briquettes These are what started this little experiment I wanted to check out the claim that “Lekto Bark Briquettes are designed for a long and slow burn for up to 8 hours”. To cut to the chase I really wasn’t disappointed, but I’ll get back to that. Similar to the heat logs these come wrapped in 12kg bags, which is probably just as well as these aren’t the neatest of briquettes especially compared to the others I was testing, having a tendency to be a bit crumbly. Despite my best efforts I could not get these to reach my normal burning temperature the best I could manage was a chimney temperature of about 250°F, which a single (1 Kg) briquette quite happily held for about 75 minutes. Given the blurb and what they’re designed for this really isn’t surprising. These briquettes are very much designed for keeping a room/stove warm and ticking over for long periods of time once it’s been warmed up by other fuels. Using them for their intended purpose rather than as a “normal” fuel they really do deliver. My first over night experiment using 2 briquettes I did get the promised 8 hours of warmth, they’d died down too much to be able to relight the stove from them but there was more than just residual heat. A second over night experiment using three briquettes was still chucking out an acceptable amount of heat ( stove fan was still turning ) with enough glowing briquette left that I was able to restart the fire from it over 9 hours after I’d put the briquettes in. Despite the very slow burn rate there’s really not much residual ash, but equally the embers also aren’t very good so getting the fire going again takes a bit more effort. All told these briquettes do seem to do exactly what’s claimed for them when used as intended, and being able to reliably have my stove ticking along over night or whilst out for the day is not to be sniffed at. I can see a quite a few of these in my future probably with normal seasoned wood for when I’m about the place augmented by these for when the stove needs to be left to it’s own devices.
Morso stove

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