Marine Installation Safety Training: Diesel fuelled heating

The safety of diesel fuelled heating systems in boats is challenged as never before
The safety of diesel fuelled heating systems in boats is challenged as never before

The history
For over 40 years diesel fuelled heating has enjoyed a faultless safety record within the marine industry. This has been achieved despite being largely ignored by most regulating bodies.

So why are we writing this? Heaters are safe right? Well, yes, if installed and maintained correctly, diesel fuelled heating is still one of the safest forms of heating you can use.

Unfortunately, in recent years a worrying trend has started to develop, fuelled by a glut of cheap second hand vehicle diesel heaters and dubious internet knowledge.

If we turn the clock back a few years, diesel fuelled heating systems for both the boat builder and private boats were fitted by trained, experienced engineers who were employed by registered dealers. This was the same for all heater manufacturers not just Eberspacher. Only occasionally would someone fit a second hand heater and if ancillary parts were required they were generally purchased from an authorised dealer who would advise on the correct marine parts to use.

Today it‘s far more common to buy a new or second hand vehicle diesel heater online and seek advice from internet forums and blogs. Unfortunately the sheer volume of “misinformation” on the internet is staggering. There is little understanding about the sort of temperatures that can be achieved by certain components, and there is almost no understanding of what happens in an overheat situation.

With the do it yourself installations our engineers are seeing today it’s clear we must do something before there is serious injury or a tragic accident.

As there is no current boat safety inspection for sea going boats, an owner is at liberty to fit whatever he wants however he wants. Unfortunately the people who fit their own heater don’t generally contact qualified trained engineers to assess their handiwork.

Recently Eberspächer UK, took the initiative to launch a nationwide accreditation program for their entire dealer and sub-dealer network. Each engineer is assigned an accreditation number on completing an intensive and mandatory training program. They are fully aware of what to look for and the consequences that could follow a poor installation. However as stated, our dealers don’t often get to see the average DIY second hand heater installation.

So as part of our ongoing effort to ensure the safe operation of our equipment Eberspächer UK with the help and support of British Marine (formerly the British Marine Federation) have launched a second initiative to help examiners and surveyors become more aware and familiar with critical points of a diesel fuelled heating installation and able to spot the dangers. With the help of inspectors, surveyors and the press we can educate people on the dangers of fitting a heating system without the knowledge or equipment to do so safely. A surveyor could inform any potential new owner that the heating system is not in a safe serviceable condition.

The auxiliary diesel fed heater used for heating a lorry cab or pre heating a vehicle engine is the same or very similar to the heater used to heat a boat by either warm air or water. This is a fact that has not gone unnoticed by the DIY enthusiast. Often a heating system will be removed from a vehicle and advertised as a complete kit, however to fit the same heater into a boat safely you would need several marine specific parts.

Things to look out for
1. Heater location
Most diesel heaters are not designed to be installed in the accommodation area where hot components could come into contact with people or animals.

Ideally a heater should be tucked as far out of the way as possible so as not to interfere with storage. If a heater has been installed in a locker, lazarette or similar storage compartment, flammable items in particular fuel canisters, oil cans, spray cans, gas cartridges, fire extinguishers, cleaning rags, items of clothing, paper etc. must not be stored or transported on or next to the heater. This can normally be achieved by a simple partition, shelf or box. However if flammable vapour is possible the source should be removed.

If fitted in an engine room or machinery space the heaters intake ducting for the air to be heated must come from a clean, fume free source.

The heater must not be fitted in any compartment containing a petrol generator or any engine room containing a petrol engine or petrol generator.

The heater must not be fitted in any petrol tank space or any other space containing flammable vapours. The heater must be secured on a metal or non-flammable bracket or mount.

2. Exhaust
A diesel heater uses a dry exhaust and therefore will produce relatively high temperatures when the heater is in use. All manufacturers use some form of lagging to ensure the exhaust is safe during normal operation. When checking a heaters exhaust, firstly ensure that it is actually lagged with a suitable material; look for cracks or splits and general condition of the stainless flexible pipe. If the exhaust is touching anything that could be flammable or heat damaged i.e. the hull or bulkhead etc. move the pipe to ensure no scorching or charring is taking place. Check behind any heat shielding or external insulation (if possible) to ensure no charring or heat damage has occurred.

Unfortunately it’s not unusual for people to use hose clips or similar to secure the exhaust to the heater or hull fitting. These clips are generally not powerful enough to crimp the exhaust onto the fitting and ensure it cannot fall off or be dislodged.

It’s common for people to buy vehicle exhaust silencers online as they are, for good reason, considerably cheaper than the marine equivalent. These silencers are specifically designed to be fitted under a vehicle, not in a boat. They are NOT gas tight or insulated.

A twin wall exhaust hull fitting must be used on fibreglass, wood or composite boats to ensure excess heat is not transmitted into the hull or transom.

3. Fuel system
Apart from the Inland Waterways Boat Safety Scheme, who specify, all heater fuel pipes in the engine room must be of metal construction, there is no other current regulation stating the material a heaters fuel line must be made of in an un-coded recreational craft up to 24m. Heaters do not currently come under the scope of ISO 10088 as it’s specifically written for engines and outboards. This will change in the next few years with the introduction of the up dated standard ISO 14895.

The fuel system should be in serviceable condition. Look for fuel leaks, perished hoses or joiners etc. It is very common for a DIY install to tee into the engine fuel line. We do not advise tapping into the engine fuel system as it can increase the chance of air or fuel leaks. This may lead to engine failure or fire. Fuel pipes should be secured at least every 500mm.

4. Combustion air
Combustion air must not be taken from any living accommodation area. Combustion air is separate from heating air; it’s drawn into the heater and used to burn the fuel then expelled through the exhaust. Ventilation requirements are taken into account during the design of a vessel and any additional ventilation air requirements, poor on board ventilation or owner blocked off/closed ventilation points may result in the depletion of available air in that compartment. Combustion air must not be contaminated with any flammable vapour or gasses.

5. Heating air duct
Occasionally you may find unsuitable ducting has been fitted to an air heater. This can be hard to spot as several different types of duct are used by different manufacturers. If a plastic duct has been used and shows signs of heat damage it should be noted, plastic can also emit noxious fumes if heated above its design specification.

Intake ducting should not be smaller than the diameter of the heaters air intake, this could lead to overheating due to lack of intake airflow.

Check that the heaters intake is taken from a clean, fume free source and does not compromise the water integrity of the boat.

In truth it’s extremely hard to put the right combination of stupidity or misfortune together in just the right way to cause a serious issue but the more people who are looking out for mistakes the safer boating will be.

Article written by Peter Collard, Sales Engineering Manager, Eberspächer (UK) Ltd and Ross Wombwell, Technical Manager at British Marine.

Addition and correction made on 4 April 2016

The Boat Safety Scheme has asked IIMS to publish a correction and clarification following the article published in the December 2015 issue of the Report Magazine and subsequently on the IIMS web site entitled ‘Marine Installation Safety Training 2015’.

The article states that “the Inland Waterways Boat Safety Scheme specify that all heater fuel pipes in the engine room must be of metal construction”.

The problem lies within the readers understanding of “pipe allowed”.

The important correction to make is that the Boat Safety Scheme allows that:

“Fuel feed, return and on-engine hoses must be marked to denote both suitability for the fuel used and fire resistance, to BS EN ISO 7840 or equivalent standard.”

The specific definitions within the Boat Safety Scheme Manual for fuel lines are:
LINE is a generic term referring to the overall facility, i.e. fuel filling line.
PIPE refers to rigid metallic lines.
HOSE refers to a line made of flexible material.

The error in the article is effectively one of omission as in the context of the above the statement is factually true, but incomplete.

The concern is that many readers might reasonably assume that ONLY metal pipes are allowed on the fuel lines to the heater.

The correct statement for the position of the Boat Safety Scheme is as follows:

The Boat Safety Scheme primarily seeks to control risks associated with “fire, explosion and pollution”. Regarding heater supply fuel lines, this requires that they are well
fitted, supported, durable, suitable for the fuel and fire resistant; this does not exclude the use of flexible hose that meet an appropriate fire resistant standard, usually
ISO 7840.

For completeness, the specific references in the BSS Examination Checking Procedures, for Private Vessels, on this subject are as follows:
2.10.1 Are all fuel feed, return and on-engine pipes made of suitable materials?
2.10.2 Are all fuel feed, return and on-engine hoses suitable for the fuel used and fire resistant?
2.10.3 Are all feed, return and on-engine pipes secure and in good condition?
2.10.4 Are all feed, return and on-engine hoses properly supported and in good condition?


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