More Bang For The buck

Buy your heating oil and fill your tank on the very cold days. You pay for your energy by the pound of fuel not the gallon. The energy of a lb of oil is measured in BTU. The colder the oil the more it weighs (more dense) and therefore the more lbs (BTU's) per tank. When the fuel warms up in your tank (assuming it's inside the house) it will expand to account for the change in density (function of temperature) but the number of pounds remains the same. Obviously, assumes that the oil temperature in the delivery truck is close to the ambient temperature. When the temperature is close to 10 below zero, as it was the other day, that would make about an 80F change in oil temp after it reaches room temp. I'm guessing that the density change is approximately 2% for a 50F change in temperature; so you'd save a grand total of about $4.00 on a $200 fill up on a zero deg day. Not much but it's fun to think about it. Hm-m-m-m same applies when filling up you car gas tank <g> MLD
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Actually here in Canada (well Ontario at least and probably the rest of the country), gas is metered and compensated to 16 degrees C. So there is no way to win really...
-Dan
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The oil comes from very large tanks, and will be at the average ambiant temperature, with averaging extending over very long time periods, on the order of a month. It is colder, surely, in winter than in summer (fill your tank in the winter, as if you had a choice). The oil does not spend enough time in transit to your house to cool off appreciably. The oil delivered when it is -20F is not likely to be any colder than the oil delivered two days ago when it was +29, both are at something like the average temperature for the month.
Your estimate of 2% is off as well, .1% is closer (based on vegetable oil--I couldn't find data for petroleum).
Gasoline comes from underground tanks and is pretty much the same temperature all year. In the winter this has no consequences but in summer it may expand when it warms from 55 to 85 and overflow your gastank if you insist on filling right to the top.

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Assuming your hair brained idea has any merit, have you figured what it costs you to heat that load of fuel back to room temp? 200 + gallons of cold fuel in your basment is going to make your furnace run a bit! Greg
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MLD wrote:

Going buy your assumptions, you would pay MORE on the cold days seeing how the oil would weigh more. So... this means you would save money filling up your tank on the warm days, and save even more if you fill up your tank in the summer time when the oil prices are lower anyway <g>
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From the ads I've seen in NY, fuel oil is sold by the galon. So, it would be more dense in the winter. But, also more expensive. I'd suggest people fill the tank in the summer, when it's cheaper. The percent or so more dense won't do much difference.
--

Christopher A. Young
Jesus: The Reason for the Season
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The figures he used worked out to a potential savings of 2% maximum. Buying in the summer can save you 50%. Ed
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Didn't mean for all this to be taken too seriously-it was all meant to be tongue in cheek---

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