Log in
Article search:

Q & A

Gas or diesel air heater

I am looking for a small air heater for a small boat but as its a liveaboard the heater will be used a lot in winter. What is the most efficient fuel?

Asked by: Adam Savory  | 6.40pm, Monday 18 May


WW says:

If you are using a blow-air heating system (with ducted air outlets) then diesel is generally cheaper to run- however they tend to use more electricity that gas-fired units.
#
The price of bottled gas versus diesel fuel (which you should be able to buy at the lower tax level for heating use, as opposed to propulsion) is the main consideration. If you are using diesel as a fuel currently for an engine, then this would be the most pragmatic.
#
If you are using petrol for a propulsion fuel, then gas may be easier to fit, as you won't have to install a diesel tank. However, ensure for year-round use that you are using propane, rather than butane, gas, as the latter does not vapourise well below about 5 degrees celcius.
#
Gas heaters can be more fuel efficient, though this does not mean they are more cost-efficient.- however there are a limited number that are type-approved for boats (some of the common Truma heaters fitted to caravans, for instance, are not approved by Truma for fitting on boats, so cannot be installed on a boat and still meet the BSS). However, they do make heaters which are suitable.
#
Many of the basic gas blown air systems only have a simple on/off thermostat, whereas some of the diesel systems have quite sophisticated variable burner temperatures, or at least a high/low setting.
#
Some electric heaters (like the Propex models) can also be fitted with 230V heating elements, to be used instead of the gas burner, which could be very useful for boats that have a reliable shoreline supply.
#
Some of the smaller diesel heaters on the market do not meet the BSS requirements, as they have plastic fuel hoses internally; however, most do and manufacturers can give more advice.
#
There are some top-tips for installing blown air heating. The inlet to the heating air (which is different to the combustion air) can be taken from the outside (for fresh air, from back inside the cabin (to recirculate)or, if you fit a manual valve, a combination of both.
#
Make the ducting as short as possible, with at least one fixed open outlet. Ducting can be insulated, which helps with both efficiency and air flow. Keep outlets as low as possible to avoid cold-spots on the floor.
#
Avoid positioning outlets where your feet will be- the outlet temperature can be quite hot and can quickly become uncomfortable!
#
Please do contact us if we can be of more help.

Mark Langley  | 10.45AM, Tuesday 19 May

You must log in to post an answer.