A post about solid fuel stove safety on boats.
Solid fuel stove safety is an important issue for boats on the inland waterways. At Marine Heating Solutions, we work on boats nationwide. Lately we have come across some heaters and stoves which were in shockingly bad condition. Many of these were posing a serious fire and carbon monoxide poisoning risk. This post is aimed to give you an initial idea of what is needed for your stove to be safe. Always contact the Boat Safety Scheme or a Boat Safety Examiner if you have any doubts at all.
So lets look at some basics like the general condition of the stove, flues, hearths, distance from flammable or combustible materials and ventilation.
Hearths are an important part of your solid fuel stove installation and need to be constructed correctly with the right materials. Stove manuals will normally specify what distances need to be kept form combustible materials. Soliftec – The Solid Fuel Technology Institute give guidance on how to construct a safe hearth for your stove.
Generally speaking, the hearth should be made of fireproof materials. Underneath the stove, this can simply be tiles, sheet metal or other non flammable materials. Some manufactures specify a 30mm base. This can be made of fire board, paving slabs, granite, or other solid materials that don’t transfer heat. Always check the instructions.
Behind the stove and to its sides, the guidelines require fire boards of 25 mm thickness to be fitted. These need to be fixed in a way that leaves at least a 10 mm gap behind the board, preventing heat from being transferred directly onto the boat’s wall paneling. Fire boards can then be tiled or glad in other non flammable materials.
Traditionally, flues for solid fuel stoves on boats were of the single skin type and made from steel. However, this has created problems in the past and accidents have occurred, some of them fatal. Single skin flues made from mild steel can rust. This means over time they can develop holes and gases will escape into the boat. Holes in the flue can be very small to begin with and the boat owner may not necessarily notice this straight away. Even a small hole can be enough for carbon monoxide and other gases to escape, posing a serious health risk.
The other problem with single skin flues is that the gases traveling inside them cool down too fast. Cold gases will not rise well in the flue. All it takes is a windy or wet day and the adverse weather conditions can create a back draft, which will draw carbon monoxide and other gases back into the cabin.
For this reason boat stoves should be fitted with double skin, insulated flue parts. These keep the smoke inside them hot and help gases to rise. Twin wall flue systems also tend to be made from stainless steel or other non corrosive material, which means they will not rot and likely wont have to be replaced for the lifetime of the stove.
Read the manufacturers instructions to check what flue length is required. Many stoves are not suited for boats as the manufacturer requires a 4.5 meter flue to be fitted. If you find that your stove is not suitable for short flues, do not be complacent about it. Short flues can leads to carbon monoxide build up, which can be life threatening.
Flues should be cleaned regularly. We recommend having your flue swept at least once a month, if you are running the stove daily.
Providing enough ventilation is an important part of any solid fuel stove installation. Every stove needs an air supply. As the fire burns it will consume the air inside the boats cabin, which needs to be replaced. There should be a completely open vent of 550mm² for each 1kW of stove output, preferably divided between vents at high and low level.
When calculating your ventilation requirements, it is also important to look at any other air consuming appliances in the boat. These can be gas cookers, boilers, extractor fans, dryers or anything else that removes air from the boat. All air removed from the cabin needs to be replaced by a vent. If you are unsure, you can check the data sheets of your appliances or contact us for more information.
General Condition Of The Stove:
When considering solid fuel stove safety, it goes without saying that the burner on your boat should be in good condition. But what exactly does that mean? Your stove should be inspected with its annual service, to make sure that the stove body is in good order. There should be no cracks, gaps or other signs of damage. The fire brick liner should be intact and fire bricks should be free of cracks and gaps. The door seals should be attached solidly and make for a tight fit. The stove must be securely fixed to the hearth, to prevent it from moving.
It is worth noting that this is by no means an exhaustive list and regulations change all the time. Always use an experienced engineer, with proper marine public liability insurance. Always follow boat safety regulations and the manufacturer’s instructions.
Make sure that you have functioning carbon monoxide and smoke alarms. These should be tested at least once a month. Alarms should be suitable for boats and labelled BS EN 50291-2 for carbon monoxide alarms, and BS EN 14604:2005 for smoke alarms