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heater on petrol engine boat

Can I install a diesel water central heating boiler on my petrol engine boat.I cant find the answer in the Boat safety guide.

Asked by: laurence  | 8.20pm, Wednesday 11 March

WW says:

First question- is it an inboard or outboard petrol engine? Also a portable petrol tank or a fixed internal one? This may determine where you can place a diesel heater, but as long as the unit is balanced flue (which not all diesel heaters are) or it is fitted into a compartment which is completely seperate to any compartment containing petrol or the engine, it should be possible.
Bear in mind that if you are relying on charging from an outboard motor, the power required by the heater from the battery might not be easily recharged from the charging coil on the engine.

Mark Langley  | 11.12PM, Wednesday 11 March

A blown warm air gas heater would probably be a better heater for your boat which I am guessing is a cruiser or small narroeboat. The electric current draw is much less than the ignition circuit of a diesel heater and you would not need another fuel on board. There are some very neat balabced flue gas heaters available, but as Mark says: it must be installed away from any compartment containing petrol.

Rupert Smedley  | 10.40AM, Thursday 12 March

The main issue, as you can imagine, is that any accumulation of petrol vapour within the boat cannot be ignited by the heaters. Petrol engine boats do fit heating systems, but they need to be carefully isolated from any compartment or space containing the engine and/or fuel tanks.
You would need to provide a space that the heater could work effectively in, drawing air for combustion from a space that is not linked to a petrol-vapour containing compartment. This effectively means from outside. Also, the heater must be outside the (potential source of) vapour- so in a completely seperate compartment. A hot exhaust from a heater would be enough to create an ignition point.
A gas boiler/heater that is completely room sealed (like the Alde Compact boiler) can be fitted- often within the accommodation space, with the balanced flue exhaust cowl mounted on the cabin roof or cabin side (if suitable distances from openings such as windows, hatches and other ventilators can be taken into account).
For the diesel heater, you would obviously need a separate fixed diesel tank. Provided the compartment is large enough, this could be in the same space as the diesel heater. Any connections, such as electrical, that could lead into a compartment containing petrol vapour must be made through vapour-tight connections.
It is quite possible to fit such heating systems though. For example, Viking Cruisers regularly fit Truma gas-fired Boatboilers (storage water heaters) and blow-air heating systems, as well as diesel fired systems. They just need care in their placing.

Mark Langley  | 10.47AM, Thursday 12 March

Readers say:

Hi thanks, its onboard and fixed tank. Electric side of problem is fine. From what you saying would same apply to a gas heater/boiler?

laurence  | 10.02AM, Thursday 12 March

Thanks again now I know what to look for I will have a look at my boat and see best way forward.

laurence  | 10.51AM, Thursday 12 March

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