As ever, we can only offer general advice on the type of fuel you should be using on your stove. Your go-to resource on whether or not you can burn household coal is the stove manual provided by the manufacturer.
Hopefully we’ll be able to flesh out some of the details and give an explanation of the information you’re likely to find in your manual.
Firstly, household coal and any similar coal-like or smokeless fuels should not be used on a wood-burning stove. Wood burners have a flat grate rather than the raised grate needed to burn coal. Not only is this impractical – since coal needs an air supply from below to burn properly – it would also seriously damage your stove, which is not equipped to have hot coals burning on it.
What about multi-fuel stoves?
Well, even with a multi-fuel stove, burning household coal is not a good idea. If you check your manual, we would expect it to warn against the use of household coal. It might not tell you why you shouldn’t use it.
The main reason is that, when coal is added to a fire it doesn’t start to burn immediately. Before it catches light, large quantities of smoke are released. This thick yellow-grey smoke is highly volatile. It will will fill your stove and flue system and, once up to temperature can create an explosive flash.
The force of this will often crack the glass in your stove door or cause damage to your flue. Even if you’re fortunate enough to avoid an explosive flash, the volatiles released by the coal will still catch fire. They will burn intensely for around 30 minutes until the coal settles into a more controlled burn.
This extreme initial burn will start to damage the inside of your stove. Examples of premature wear you will see include twisted baffles, misshaped grates, pitted and cracked liners and warped fuel retainers.
For those reasons, household coal should only be used in open coal fires. The ventilation of air from the room into the open fireplace dilutes the volatile smoke and stops the flashes and intense burns that make coal unsuited to the more confined conditions of a stove.
What should you use instead?
Manufactured or smokeless coals are a far better option when it comes to finding an appropriate solid fuel for your multi-fuel stove. They are made to burn more consistently and steadily.