What is Over-Firing?
Each year boat fires are caused by solid fuel stoves 'over-firing'.
When the fire intensity picks up and races away, usually the air supply is closed down to reduce the roar of the fire. But if the fire races out of control, this is 'over-firing'.
As the fire roars, the flue gasses gain heat and then speed as they go up the chimney.
Matters get worse until the appliance glows red and then two things can happen:
- Any build-up of soot and tar in the chimney, can catch fire, and/ or
- The super-hot stove or chimney can set light to furnishings, fabrics or other objects nearby.
How To Avoid Over-Firing
You need to get used to how your stove and the fuel behaves, until you do:-
- be cautious about air control
- be cautious when using an unfamiliar fuel
- don't bank up your stove with fuel and leave it unattended whilst going off for a day's work, a spot of shopping, or bite to eat
Before leaving the boat for a period, or retiring for the night, or travelling through a tunnel always check that the appliance air controls are set to prevent over-firing.
In standard, normal conditions you may be used to controlling your stove, but air control can be affected:-
- If your stove has a lower ash door which can be opened separately from the main door don't leave it open even for a short time even whilst taking the ash out.
- Damage that allows air to enter the fire box will affect your ability to control the air supply to the fire. See the section on use and maintenance.
- Stormy or gusty weather, with winds whipping across the chimney top and flue gases being sucked out with a draw two or three times the normal strength.
- Take account of the wind effect when setting the air control and it's best not to leave the fire unattended.
Fuels and over-firing
Only use the fuels recommended by the manufacturer. Smokeless fuels, or dry wood are the best ones.
Get used to any 'new' fuel's burning characteristics when you are around to keep an eye on it.
Avoid bituminous coal (sometimes called housecoal or Polish coal) as this produces more flammable gases which can make it difficult to control your stove.
If you generally use a smokeless fuel, banking up with logs and wood can catch you out because the burning behaviour of wood is more volatile than smokeless fuel.
The other important points
Be very cautious about banking up the stove when it's windy outside or strong winds are forecast. If in doubt, feed the fire little and often.
Keep the flue swept to avoid a chimney fire and in case over-firing happens to you.
Using fuel that burns too hot and/or using a stove with damaged or missing liners (firebricks) can further damage your stove through overheating.
If over-firing does happen, try, if it can be done safely, to close the air inlet control, but watch out, the stove and the area around is likely to be extremely hot.
If you cannot safely get near it, or if it has already led to a chimney fire, then get everyone off the boat and call the emergency services.
Alert anyone in nearby boats and buildings for their own safety if the fire spreads.