Spike's Oil Heater

Pla

My Heater .
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Unfortunately I can't find the photos of my very first attempt at building this type of heater, but I will suffice to say that it had two more drums on top and was a damned heavy monster of a thing, it was over six feet tall, supported by three legs attached to a steel clamp running around the lowest drum just below the top lip. It's looks alone condemned it to the junk heap. At left is the earliest photo that I can find at the moment, and this was taken the night I first brought the completed "Heater MkII" indoors just to get an idea of how hot it was going to be. At right we see it after I had taken it back down to the fuel storage shed where I could easily run some more tests on it while I fiddled with the configuration, number and size of holes in the secondary burner. Once this was completed to my satisfaction, I put it back in the Living room and that's how it remained for the next 10 or 11 years. Over this period I did think of a few small things that I would like to try to enable it to burn cleanly over a wider temperature range, but the fear of making a mess on the carpet inside plus a good healthy dose of cowardice prevented me from ever doing anything about it. While it was all working reasonably well, I was very happy to leave it be, not wishing to upset anything. Something that builders should take note of here is that the fuel line and metering valve are positioned below the pan out of the radiant heat. This is done for two reasons" So you don't burn your fingies when making adjustments. To minimise the change in viscosity of the fuel through the metering valve as the heater warms up. (Thinner fuel runs faster) and although you don't exactly get a "run away", this can cause the temperature to overshoot and undershoot.
During this period a number of persons built heaters, but one was especially interesting, as he was located in the Midlands of England, had a strong Mechanical and Engineering background, he was also very enthusiastic and we got into many long and involved discussions via email. He worked in an industry where he had access to a large amount of used oil and wanted to try using a heater to take the chill off one of the machine shops. Allister's story is on Page 3. I told him of my ideas and of course he said, "If you're so sure these ideas will work, why hven't you tried them on your own heater"?..... Good question,.... So, I was eventually shamed into promising that I would do it as soon as the weather warmed up nd I could get the heater down to my shed . There was no doubt that ir really needed some TLC anyway, a it had not had any more than a daily ah clean for the whole time that it had been in use. This was made worse by the fact that a leak around the flue had allowed water to run down the back of the heater and it had a bad case of rust starting to show. It just so happened that my wife was due to go and visit her elderly Mother interstate for a month over Christmas. Being the coward that I am, I waited until she had gone before spreading several layers of plastic drop sheets all over the living room carpet, bringing my industrial vacuum cleaner in, and got stuck into the job of lifting the flue, cleaning out the ash and soot, dismantling and moving the pieces outside. The first problem was that in the eleven years since it had been assembled the heat and soot had virtually welded the bottom spacer rod onto the left hand throughbolt, necessitating some rather cramped work with the 4" cutoff disk so I could get the firebox apart. This could be re welded once I got it all cleaned up and up in the shed. In the photo at right you can clearly see the two front securing bolts for the lid, these had always been a nuisance, as they prevented me using the top as a stove top for all but the smallest of saucepans, These were listed to be cut off and the remaining studs to be welded into the top and neatly ground off . Also a new flush fitting lid was to be put in place, being supported by an internal lip around the access hole.
Once all the pieces had been transported up to the shed and cleaned thoroughly with the high pressure sprayer the first thing that became apparent was that the secondary burner tube was in a much poorer state than was able to be seen while it was in service. It was found after it was installed initially, that it had many more holes in it than were needed, and to adjust the airflow I had merely strapped a 2" wide piece of galvanised iron over several rows of holes and secured it with a large hose clamp. It was the area behind this that had overheated, and the pressure caused by it's expansion had caused it to bulge out at the rear and it was also badly "crazy cracked" mainly being held together by the surrounding band. Much of the damage was exacerbated by the fact that the pan had until now been held against the bottom of the secondaty tube by two large bolts and once tightened, they had no "give" in them to allow the tube to expand as it heated up, it was this crushing that bulged the tube. To overcome this was going to be easy as I had already decided that the secondary tube was far too long anyway, so, it was duly trimmed off along the line of the second row of holes, this shortened it by about 4". Further shortening was not practical, as some room had to be left between the bottom of the firebox and the top of the pan so that the dripper and locking mechanism could be fitted. The photo at right shows the trimmed tube having been marked out ready for an experimental set of holes, it also shows signs of previous experimentation with several rows of holes around the top having been welded over with nickel electrodes. The problem of the crushing was fixed by placing compression springs between the securing bolts and the strongback which supports the pan.
Initially the support enclosure was just made as a 60cm cube as I had little idea of what room would be needed as I built the heater from scratch. Now the secondary burner was shorter and I knew that much of the height was not needed, I thought that it would look tidier if the whole support structure was lowered by about 10" or 25cms. To lower it further would make it too hard to get the pan in and out for cleaning, also a completely new door would have to be made and a new piece of Pyrex glass would have to be found. It was just all too much trouble..... In the photo at left I have just started to cut down the old support, with the finished job at right. I feel that to have this support enclosed with a removable door is quite important, it was originally done to lessen the noise and the volume between the outer galvanised sheeting was filled with rockwool batting both to help absorb the noise and also to reduce the radiant heat transfer to the outside. The batting was not replaced in the rebuilt unit seen above at right, but it was enclosed with galvanised iron sheet as a fire precaution should anything ever go wrong
The last major job was to make a new lid for the primary pan, as the old one was made of a spring steel disc plough shear which was welded to the bottom of the secondary tube. this had caused problems in that the two metals had differing rates of expansion, and the welding would crack after a few years. It could not be easily re welded without dismantling the heater, so a new arrangement was in order. This caused some head scratching, but in the end I decided to have a new flat steel plate lid, cut out of 6mm plate. It would locate onto the top of the pan by having a rim welded around the rear half and to align the whole assembly under the secondary tube a similar stopper was welded around the front half of the centre hole. In these photos you can clearly see the latest arrangement of six primary air holes drilled equidistantly aroind the lid. The air coming in through these holes mixes with hot vapour within the pan and ignites, sweeping small flames down across the top of the oil in the pan bottom
Plans for this Summer. The heater has worked extremely well this winter, but I do still have some new Secondary Burner Tube designs to try out in an effort to get the flame higher up into the firebox, also I will be lowering the metering valve which will also entail relocating the extended drive. The biggest job wil be to put a baffle plate in the firebox to spread the heat to the outside rather than having 80% of it just pass straight through the firebox and out the flue. The outer rim is going to be made from a 2 cm., thick cast steel Mack truck clutch plate with the centre hole covered ny firebrick.