Spike's Oil Heater

A Quick Guide to Assembling Spike's Heater

The Primary Burner Assembly. (Pan)

This is where the fuel is heated and vaporised. Only a small proportion of the fuel is actually burnt in the primary pan, the purpose of this is merely to provide enough heat to vaporise the remaining fuel into a hot carbon rich gas which does not burn because of the oxygen deficient atmosphere in the pan. This oxygen deficiency is achieved by only providing six small (6mm) air holes equidistantly spaced around the lid of the pan, otherwise, the pan assembly is as airtight as you can possibly make it.

Inside the pan there is a length of angle iron welded to the side and projecting slightly downwards into the area of the pan immediately below the opening into the Secondary Burner Tube, this is heated by the flame within the pan and in turn preheats the oil before it flows onto the floor of the pan. This way, you have no preheating coils prior to the oil flowing into the pan, preheating coils are often a problem as they tend to get too hot and carbon bakes onto the inside blocking the flow, once blocked the carbon is not really able to be removed and the coil must be thrown away.

The Dripper and Locking Mechanism.

The dripper itself as simple as it sounds, being no more than a small (6mm) tube to guide the flow of oil into the pan via the guide trough within the pan. The locking mechanism can be seen in the photo above located on the lid of the Pan. It is two pieces of pipe that neatly fit together, the smaller 3/4" tube is welded into a hole in the lid, a slot cut in the inside edge and across the top plate to allow the dripper tube to slide into the centre. The outer tube fits neatly over the outside if the inner tube and also has a slot in one side and halfway across the top, so that when the outer tube is rotated 90 degrees it locks the dripper tube into the centre of the assembly. This stops the lid and pan from being able to be withdrawn from the heater. At the same time as the lock is rotated, it aligns the holes in the front of the assembly allowing you to see the flow of oil off the bottom of the enclosed dripper tube.

The secondary burner shown in this photo is an experimental one having only small holes, it did work, but was very slow to start and only had a very narrow clean burning range, Ithink that this was due to the fact that the small airflow did not mix the fuel and air enough .

The arrow is pointing to an alternate fuel inlet, where one day, hopefully, I will attach my lighting fluid connection.

The Secondary Burner Tube.

In this tube, the hot over rich oil vapour is mixed with the main air supply, this flame provides most of the heat. In the photo at right, you can see one of my experimental tubes with old holes that have been welded over, and new hole patterns being marked out . I always drill my holes small, and then enlarge them as I need to, by doing it this way it is much easier to control the air mixture . For example I might feel that the fuel and air is not being mixed violently enough, so the answer to this is to make the holes larger.

For a start I will only drill out a few holes, and we now see one of the reasons why I have chosen to have 32 hole rows. This gives me a large variety of hole patterns that can be drilled out evenly around the tube, 2, 4, 8, 16 etc. It is also very easy to mark out when you start by marking a line acros the end of the tube and then successively halving the angle, halves, quarters and 16ths etc. Once you have the first line of holes marked out you need only score lines above that row and drill your next rows half way between those below. Another benefit of using old Cylinder liners is that not only are they very heat reistant, cast iron is very soft and easy on your drills.

When you decide on a size of cylinder liner go and get them from a larger Diesel engine maintainer, as no doubt he will have whole sets of used ones, which are all the same size and shape, grab half a dozen all the same and you are setup for life. No scrounging around ten years down the track trying to find ones that match your existing setup. Only Nickel electrodes will weld soft cast iron easily and successfully should you ever need to do it.

The Firebox Bottom Plate.

This seals the bottom of the Firebox, which rests in a rebate cut around it's top edge, This plate effectvely supports the whole heater on the framework or legs below. Mine is made out of an old truck flywheel and is approximately 20mm thick giving me plenty of thickness, into which I can turn the top rebate for the firebox, and also the bottom rebate on the inside of the centre hole to locate the top of the Secondary Burner.

The secondary burner is held in place with four bolts each of which has two projecting fingers, which tighten against the rim of the Burner tube.

The greatest part of my experimentation to achieve chean and economical burning is focused around variations of size, placement and number holes in this tube. My best result so far being achieved with an arrangement similar to that shown at left. The small 6mm holes around the bottom both heat the gasses coming from the pan, and also radiate heat down on top of the oil. The larger holes drilled just below the top of the tube ensure good mixing and enough air to support the main part of the secondary flame, this is as high as possible in the tube to help maximise the radiant heat transfer to the firebox. So the flame is actually up in the firebox rather than down lower in the tube.

The Firebox.

My firebox is made of two discarded heavy truck brake drums, these are worn out and can usually be picked up for nothing from most trucking companies that do their own mainenance, or at most you will be asked pay a token amount for their scrap value, they are also reasonably neat looking, once put together resembling a normal Pot Belly stove.

You will notice on the drawings that they have rebated edges as shown at left, and if you look around you will find that one will slip perfectly inside the other. Once again, these are made of thick cast steel and are very heavy for the purpose for which we are using them 30kgs+, I do not expect that they will burn out in my lifetime.

In the photo atright, I have large pyrometer sticking rather untidily out of the top. This has since been moved onto the top of the smokebox giving me room to put the kettle or saucepan on the top plate. It needs a bed of scrunched up aluminium foil under it to reduce the heat transfer or the kettle boils far too hard and is dry in no time.

The Lid and Smokebox.

The Lid is made of 6mm thick plate steel, and welded to it I have a Smokebox. The smokebox serves no other purpose other than to align the flue outlet with the existing flue in my livingroom, if I were to have just welded the outlet into the middle of the lid, the heater would have been almost right against the wall behind, and the heat would have ruined the wall. As it is, the plaster immediately behind the heater is crazy cracked from the heat.

Originally also I also experimented with putting a damper in the smokebox, but found that as soon as I tried to use it, the velocity of the air entering the secondary burner decreased, and the fuel and air no longer mixed as well as is needed to make the fuel burn cleanly. So that idea was abandoned.

I believe that there is no operational reason why you could not attach the flue outlet to the side of the heater, as this method is used in the case of the Kroll heater. The only alteration needed is that tyou will need to fit an internal baffle plate, tol allow the heat to circulate in the firebox prior to exiting up the flue. I did not do this because I am too lazy to go to all the work of cutting a 6" hole in one of my brake drums and then attaching an adaptor piece to the flue.