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Burner assembled to the boiler using studs to space the combustion chamber and burner chassis at the correct position. A 6"diameter stainless heat shield covers the combustion chamber- it gets very hot [c. 500ºC ] near the boiler end but fan airflow keeps it cool near the burner. PTC heat tape [red cable, exposed here for the pic] is applied to the VO supply line, raising its temperature to about 55-60ºC prior to the Danfoss FPHB 5 preheater, which again raises the temperature close to 70ºC. The Danfoss preheater delays ignition till the oil is hot, with an integral thermostat linking Controller pins 3 & 8. The run is insulated with foam tube.


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Boiler room view. I motorised an old dairy-cream separator to centrifuge the VO. 5000G in the rotor traps most of the crud & will process about 20 litres an hour. Note; these machines will not remove breadcrumb or any other floating debris, [such as dried herbs from my pizza-parlor guy!]. The crude VO is pre-warmed to about 50ºC with a deep-fat fryer element fitted in the bowl. This prevents animal fat, which is always present in small amounts in my waste VO, from choking the separator cones and it also gives warning of any water present by 'popping'. The final operation is to 'polish' the VO by pumping it through a 75 mesh strainer and a 20 micron wound cotton filter directly into the VO tank while it's still warm. I have a 150w immersion 'lance' to heat cold oil for the 'polishing' operation if necessary.


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The burner works superbly, starts reliably and cleanly and stops without dribbles, with the combustion chamber running at a red heat [c. 600ºC] once up to temperature. The flame is longer but my boiler firebox can accommodate it without flame impingement on the heat-exchanger surfaces. I'm still on a steep learning curve with both the burner and handling the VO and will be still playing with 'improvements' as the winter progresses.



Alan