Fuel conversion cost

[Philip Saunders]

Hello everyone - sorry if this is a little off-topic but I don't know where else to ask.

I currently have an oil fired heating system that runs on gas oil/diesel. Given the current price difference between kero and gas oil (about 14p per litre) is it worth converting the boilers to kero? Usage is about 800 litres per month.

I've been told that the fuel is cheaper but I would use more - I have no idea how true that is and I can't find anything online that helps.

 

[John.g]

Kero has a heating value of 10.18 kwh/litre & gas oil 10.55 kwh/litre so assuming the same boiler efficiency then your effective saving is still 13.51 p/litre, you will have to get a boiler service and the oil pump pressure changed so well worth it as long as your boiler is suitable for conversion.

 

[SJB060685]

Kerosene has a slightly lower calorific value than gas oil so yes will burn a bit more to get the same output. Switching back to Kerosene is simple, the pump pressure will be lower, a new suitable nozzle and the combustion reset as different fuels have different CO2% and excess air, this is all stuff you're engineer should be capable of doing.
Having said that do you have a standard efficiency boiler if you're running gas oil? You might consider upgrading to high efficiency condensing boiler as well if you're making the switch.

 

[Philip Saunders]

Thanks guys - I'll get quotes to do the conversion - looks like it will be worth doing. Replacing the boilers (2) would cost many thousands and isn't viable right now given that they work flawlessly even if they're not as efficient as they might be

One further question - if I use the gas oil in the tank until the boilers cut out, then have the conversion done, when I have the tank refilled it will mix with the gas oil in the bottom of the tank that is below the outlet - a volume of about 200 litres. Do I need to have this drained or will it pass through the boilers mixed with the kero and still burn?

 

[SJB060685]

Gas oil is slightly more dense than kerosene, so kerosene should sit on top with minimal mixing, having said that I would suggest pumping out the remaining gas oil to eliminate any potential, all be it minor mixing. As I said CO2% and excess air change with different fuels and grades, so trying to set up a burner with mixed fuels will most likely result in a sooty boiler for a short time.
You could hire someone to do it for you or purchase some kind of suction pump and drain into a suitable container yourself.

 

[John.g]

Neighbour of mine left ~ 20/30 litres in the tank before Kero fill and then before each new "fill" would throw in a drum of 20 litres, it took him around 3 years to get rid of the remainder or maybe it is still all sitting on the top.
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should have said sitting on the bottom.