Q. Down Draught causes flame to blow out (hear "popping" sound)
A. Negative Pressure - This is caused by the flue exit being sited too near some structure or influence (sail downdraught) that creates a localised pressure greater than the inside of the cabin. Typically it occurs when high winds hit the boat at a point i.e. where it hits the mast a deck house or a stowed dingy, close to the flue cowl. The flue should be raised high enough to take it clear of such influences. Time and thought in fitting, to find the best practical exit point through the deck, is well spent. In extreme cases an "H" cowl can be fitted in place of the standard cowl.

Lack of adequate pre-heating - extinguish burner, allow to cool and re-light using longer pre heating period.

Flame pipe above deck too short or not insulated - extend length and ensure that pipe above deck is insulated to guard against a 'cold' barrier at deck head.

Q Fuel backs up in the drip feed sight glass
A Drip feed rate to high - The ideal drip rate will vary with climate and season. Reduce the drip rate accordingly.

Carbon build up in burner pot - Clean the burner pot paying particular attention to the fuel entry point in the base. On heaters made after 1989 where a "T" junction is fitted to the pot base, the fuel entry point can be cleared externally.

Air lock - Not usual but air locks can be cleared by momentarily releasing the nut securing the fuel pipe at the base of the drip feed sight glass and re-tightening. In some cases it may be necessary to drill a 1/32" (0.8 - 1.0mm) hole in the metal part of the sight glass body, just above the glass, this will help relieve air locks.

Fuel drip rate slows and stops
A Air vent on tank not open - Unscrew the tank filler cap off its "O" ring sealing enough to allow air into the rank via the hole in the cap edge.

Faulty magnetic safety valve or thermocouple (blue button) - First check that the thermocouple probe is located through its hole in the burner pot ( upper rear left hand side when looking through the door). Check the other end of the thermocouple is properly secured by its nut into the valve. Renew the magnetic control valve or thermocouple as necessary.

Drip feed valve needle loose - Check that the gland nut, where the control needle enters the drip feed valve body is tight enough to prevent too much free movement of the needle, shaft, possibly through engine vibration. The needle shaft should also be lightly greased to eliminate backlash where it is gripped by the "O" ring.

Suspect fuel - Unfortunately the quality of diesel fuel is not always constant. The in-line fuel filter provided with all new models and also available as a spare part should be fitted - Dirt in the fuel tends to be obvious and it can be filtered. Some fuel seems to build up sediment in the metering valve particularly around the needle. To clear it, all that is needed is to close the valve to physically clear the sediment and then open it again.

Fuel waxing Diesel fuel will wax in very cold conditions to the extent that it will no longer flow. If it is not possible to move the tank to a warmer place then insulate the tank and also the fuel supply line. Anti-waxing fuel additives are also available.

Fuel tank not high enough above valve - The relative height of the fuel tank above the valve i.e. "head of fuel " is Important. The closer the tank to the appliance, the smaller the head required.

Q Black smoke emission, Inefficient burning and excessive carboning
A Too much / too little fuel - In most cases the problem is caused by trying to run the heater too low. Either too much or too little fuel will result in black smoke and soothing up. Ideally there should be some blue colour in the flame. Controlling the drip rate accurately is crucial.

Flue not long enough - Poor draught will result and lead to heavy carboning, and soothing in the heater body and flue. The minimum flue length is around 89Omms (35 "). If it is not possible to increase the flue length inside the cabin, it can be added outside. If this is done, be sure to insulate the outside section (use heat resistant material) otherwise the temperature differential within the flue will tend to cause a down-draught.

Dirty flue - After a period in use the flue will start to soot up even given the cleanest burning. This soothing will be obvious if you look down the flue from on deck and it should be cleaned before the problem gets worse.

Q Heater is difficult to light
A Strong draught Given an efficient flue, the resulting strong draught can cause lighting problems (when matches blow out etc,). An alternative method of lighting is to use a short length of paper towel soaked in methylated spirits. Pass the end through the lighting hole and then light it.

Wrong fuel for pre-heating - Pre-heat with methylated spirits (alcohol)

Q Can DIESEL heaters be run on PARAFFIN
A YES - Or on a mixture of both


Q Burner flares up when first lit, after pre-heating
A Insufficient preheating - To burn paraffin (kerosene) cleanly, it is necessary to vaporise it with high initial heat. Until you get to know how much methylated spirit is required for adequate pre-healing, it is better to use too much than too little. It is important to let the burner cool if you need to go through with the preheat process again. NEVER pour methylated spirits over a hot burner. We suggest that you seriously consider using a small gas blow torch for preheating.

Q Burner flame slowly reduces
A Tank too full or balance of fuel to air too great - If the tank is filled more than about two thirds full, the pressure will drop quite quickly due to lack of air space. During continued use fuel in the tank will decrease and pressure will drop. The solution is to re-pressurise to 20-22psi.

Carbon build up in burner - Carbon will build in the burner and this can occur quite quickly if inferior quality fuel used OR A LOW BURNER SETTING IS USED. Always use the best fuel available. It is a good Idea to get into the habit of tapping the burner while alight, with the handle end of a knife. This will help dislodge carbon which you will see being burnt off as sparks. It is advisable to do this just before shutting the burner off to minimise the risk of solidifying. Carbon can also be cleared by removing the burner and soaking in ammonia. If the burner is totally blocked it should be replaced.

Main jet blocked - use "self pricking " system to clear. Rotate control knob fully anti-clockwise. It is also a good idea to get into the habit of using this procedure on a regular basis before shutting down your system.

Balancing jet blocked - Remove the burner and clean balancing jet. Suspect dirty fuel, ensure the in-line fuel filter is fitted. 

Q Strong smell of paraffin
A Paraffin spillage in the pre-heating cup - Clean outside of burner and check for leaks.

Fuel leaks at the gland packing screw - You may find that, due to expansion when the burner is hot, a leak will occur at the gland packing screw. This leak will show a vapour or maybe a small flame. This happens particularly when the burner is new and the graphite packing washer is not settled in OR conversely when it is worn. Tighten the gland packing screw just enough to stop the leak. If necessary replace the packing washers.

Q Irregular burning (blue one side of burner, yellow the other)
A Carbon build-up on the main jet - Turn the burner control knob fully anti-clockwise to the "Clean" position to operate the cleaning needle. Repeat a few times. If this keeps happening, suspect dirty fuel. Strain the fuel and ensure that an in-line fuel filter is fitted.

Burner caps. outer and/or inner not seated correctly - Check that both caps are sitting correctly. square with the burner top, and not tilted. Clean any carbon deposit that may have built up in the burner caps.

Main jet worn or faulty - Replace.

Tank pressure too low - Normal working tank pressure, is 15 25 psi but pressure should not be allowed to drop below 15 psi. Re-pressurise tank.

Faulty pressure gauge - If the flame is consistently too low, test the pressure gauge against a tyre gauge as it may be over reading, thus making the tank pressure too low.

Carbon build-up in burner - See answers for "burner flame slowly reduces"

Q Burner rupture
A Excessive pressure in fuel line - Replace burner.

Note: with a safely control valve fitted in the fuel line, so that the appliance can be separated from its fuel supply, it is very important that this valve is OPEN before preheating starts. If it is left closed the fuel/air between the safety control valve and the burner control valve will expand, possibly to the point of rupturing the burner gallery. The burner will then have to be replaced.

Burner damaged through incorrect removal - Replace burner.

Note: to remove the burner from the heater, it is necessary to use 2 spanners. Having undone the lock nut, use one on the connecting nut and the other on the burner base. Tempting though it may be, NEVER hold the burner around the body with your hands while using a spanner. WORSE STILL, NEVER PASS A SCREWDRIVER OR SIMILAR TOOL, BETWEEN THE FEED PIPES AS THIS WILL FRACTURE THE BURNER BODY AND CAUSE LEAKAGE.

Q No fuel to burner
A Not enough fuel or pressure in the tank Check the fuel and pressure levels, particularly if the boat is occasionally heeling away from the tank exit point.

Cleaning needle blocking main jet - Check that when you turn the burner knob anti-clockwise to the "clean" position the needle can be seen working. If it cannot be seen, remove the main jet and inspect. Replace the cleaning needle if necessary.

Dirt in fuel - Check tank and fuel supply line for blockage. Ensure you have fitted an in-line fuel filter in the fuel line from the tank.

Q Burner flame "surges"
A Balancing jet not in place or worn oversize.

Check that the balancing jet is in place as without it the burner flame can surge to the point at which it goes out. If the jet is missing, replace. If the jet is worn from repeated cleaning, replace. In an appliance using a single burner, such as a heater, it is sometimes possible to substitute the balancing jet by throttling the fuel flow with the safety control valve, keeping it just cracked open. This will not work where more than one burner is involved. The flame surges if the burner is more than 2' from the tank. The burner creates more pressure than it can use and vaporised fuel forces liquid fuel back against the tank pressure. As the burner demands more fuel, liquid surges back to the burner making the flame surge. Hence the need to make some restriction in the fuel line close to the burner i.e. the balancing jet.

Note: If you have 1/4" fuel pipe and no lock nut on the bottom of the burner, you will have an old specification burner and will need to replace the pipe work to put in a new burner with the balancing jet (contact Blakes Lavac Taylors. for details).

Q Fuel continues to come through when control knob is OFF.
Spindle point worn or blocked or does not seal - Check the pricking needle is positioned correctly then clean or replace.

Q Tank looses pressure
A Faulty non-return valve at base of pump - Replace pump.

Check tank for leaks with a mixture of soapy water (leaks will blow bubbles)

Q Where can we find paraffin?
A In the U.K. a company called Caldo Oils, St. Helens, Lancashire, Phone
01744 813535, produce a very good quality paraffin, and if you contact them they
will advise nearest stockist. Otherwise paraffin can normally be obtained from
garden centres like Homebase etc because it is used to heat greenhouses.  The
big advantage of paraffin equipment is that it is very economical on fuel and if
you carry a 5 gallon container it will last a very long time, and can be
topped-up before it is all used.  Paraffin can normally be obtained overseas
around marina areas or from the equivalent of hardware shops.  A customer in
Greenland informed us that he uses jet aviation fuel which he can buy from his
local, small airfield.

Q How long does a tank last?
a gallon of fuel will last about 30 hours.


Copyright 2001 Blakes Lavac Taylors
Last modified: August 26, 2004