Keeping warm - logs or coal ?

[masochists-r-us]

As we're still largely without central heating, we were quite concerned to hear that our source of seasoned wood had dried up last week. We have two multi fuel stoves, but thus far hadn't tried out coal, suspecting it would be an expensive option. Interestingly, we have found that smokeless coal at approx. £5.00 per day is indeed more expensive than wood (approx. £3.65 per day) and disappointingly does not kick out the same amount of heat. However, coal does last much longer than wood and stays in and warm all night. Surprisingly, overall, the lower temp staying alight longer has made the house feel much warmer than with wood alone. Also, although coal makes a bit more ash to dispose of, the effort involved in lugging it around is far less than wood.
Any thoughts to share, anyone else ?

 

[worms]

My view is that coal is dirty horrible stuff, but burns hotter, can always be bought at short notice and requires very little work. Ecological aspects apart, my top preference would be peat!

 

[philpjuk100]

We have found the same on both our stoves,we ran out of logs a few weeks ago so am using coal,(we used to use it to get the logs going),the stoves produce more heat,need feeding less often and are cheaper per day,on the down side the ash requires emptying every day against three or four days for logs,storage is less of a problem and as the coal does not "spit" like logs we are able to keep the doors open to benefit from the radiant heat,(still looking for logs though!)

 

[Flyfisher]

Some interesting figures here: http://www.biomassenergycentre.org.uk/portal/page?_pageid=75,20041&_dad=portal

Basically, coal contains about twice the energy of air-dried logs, but the impact of this will depend a lot on how the stove burns each fuel.

Also, although M-r-us said that burning coal was more expensive than wood, it was also mentioned that coal would 'stay in' overnight and that the house felt generally warmer, which could imply that more heat energy was being released when using coal, which could be why the cost was higher.

There can be a lot of anecdotal information surrounding stoves and fires and there are so many variables that it's often quite difficult to draw definite conclusions. I've known people to consider a wood stove 'efficient' because the burn rate can be slowed right down, thus making the wood last longer. The fact that this results in a lower heat output is often overlooked!

 

[DJH]

I'm not sure if you need special baskets when using coal as the heat generated by coal in an over heat situation for example if the door or damper is inadvertently left open, can melt and distort the basket and any steel liners in the stove. I know, it's happened to us with one of our stoves where the basket distorted and moved forward enough to cause the glass in the door to break when we shut the door. It cost us a cool €39 for a new glass for the door and to cap it all the screws holding the fixing clips for the glass sheared off as they had been baked in by the heat of the stove.

Doug

 

[88v8]

We buy logs, have a choice of several suppliers although I wouldn't trust them all equally.

Never used coal here. It does burn a lot hotter, less bulk more heat. The economics would party depend on the cost of your logs, and how well seasoned they are, and what they are. Not all logs are equal... If wood is not properly seasoned you can end up using three/four times as much. As we found out this winter....

I assume you have stovepipe thermometers on your flue pipes so you can check the stove isn't running too hot. Otherwise as Doug said you can damage the stove, and burn out the flue liner.

Ivor

 

[Jellyfire]

We generally burn logs as a rule except when it's particularly cold, then the we use coal as ts so muh hotter. If you're not getting as much heat out, it may be you're not ventilating it from the bottom. Wood burns best say in a bed of ash, coal likes air circulating up through it I believe.

Regarding wood, we have been buying seasoned hardwood from the same supplier for a couple of years, I was a little suspicious how seasoned I actually was so I bought some from elsewhere, and was amazed how much hotter and longer it burned for. Motto being its worth testing out a few options, cheapest isn't necessarily bet value!

 

[Flyfisher]

The economics would party depend on the cost of your logs, and how well seasoned they are, and what they are. Not all logs are equal... If wood is not properly seasoned you can end up using three/four times as much.

I've read that, weight for weight, wood has pretty much the same energy content, so it's best to buy by the ton rather than by the bag if you can. But, even so, the biggest variable will be the moisture content. Not only does moisture increase the weight of the wood (not good if you are buying it by weight!) but it reduces the heat output because a lot of heat is wasted in boiling out the moisture.

I've never tried it, but I wonder if this could actually be a good application for the infamous damp meters beloved by so many surveyors? I suspect that a moisture measurement of the surface of a log might not be that useful on its own, but perhaps measuring the inside of a freshly split log might be a good indicator. A lot of faffing about though!

Coal has its own problems, of course, but its generally a much less variable fuel.

 

[DJH]

We use smokeless coal, which comes in egg size and shape lumps, in the main stove which stays alight day and night apart from one day each month, when I clean it out and brush the length of horizontal flue which exits the back of the stove. It costs just over €18 for a 40 kg bag buying a ton at a time.

In the others we use coal to provide a hot bed of embers on the grate basket and feed it through the evening with wood cut up from pallets. Not only is there a lot of heat from pallets, as they are invariably dry after being kept under cover for a while, but we get to tidy up around both us and our neigbours farm. I cut them up with a jigsaw and very rarely hit a nail with the way I cut them. The ash goes on the garden and the nails add a bit of colour to Mrs DJH's hydrangeas.

Doug

 

[Penners]

Not only does moisture increase the weight of the wood (not good if you are buying it by weight!) but it reduces the heat output because a lot of heat is wasted in boiling out the moisture.

In addition to the above, habitually burning damp wood can accelerate the destruction of your flue liner. Damp wood burns cooler and its combustion products are higher in moisture - a recipe for condensing out the acidic tars on the surface of your flue liner.