It's Wise Not To Let Oil Tank Get Too Low

HOME CLINIC: Since this was such a mild winter we didn't use as much oil as usual. In fact, we didn't get a delivery back in February. Now our tank is getting pretty low, but I'd like to hold off on delivery until oil prices are at their lowest. How long should I wait? My neighbor says I shouldn't run the tank empty. - C.F., Seattle

DEAR C.F.: We can appreciate your desire to save money. Filling your tank in the middle of summer will usually get the lowest price. You probably cannot empty your tank, but you could run into problems if you run it too low.

We talked with Ron Glatz at Rossoe Oil to get some professional advice about how low you should go. He tells us the typical oil tank is about 294 gallons. The amount in the tank is measured by a dip stick with inch increments on it. Most likely your furnace will stop running if you let the oil level get down to about 4 inches. This is because the feed line to the furnace picks up the oil about 3 to 4 inches above the bottom of the tank.

Your neighbor is giving you good advice. If you have an older tank, there is a good chance that impurities or sediment have settled out in the bottom. If water has leaked into the tank, it will lie on top of the oil and make the dip stick indicate a deeper fuel level than is actually there.

When you get down to the lower levels, there is a greater chance of sucking water and impurities into the feed line. This can clog the nozzle and prevent the burner from operating properly, making a service call very likely. You can save yourself the trouble by keeping the minimum fuel level above that 4-inch point.

Aside from buying fuel when prices are low, some of the best ways to save money on heating costs are to keep the furnace tuned, set back the thermostat at night (5 degrees or more) and insulate the house.

You can monitor your fuel use by checking the fuel depth frequently. But Glatz cautions that this can be deceptive because the bottoms of most oil tanks are rounded. This means the inch mark on the dip stick at 20 inches represents a lot more fuel than the inch mark at 5 inches. While it may take several days to drop from 20 to 19 inches, you could burn up the fuel from 5 to 4 inches quite rapidly in a day. You might find yourself without heat until you can get a delivery.

Glatz suggests you not let the level drop below 8 inches so you won't get caught short. If you have a regular oil provider, they may be able to supply you with a chart that estimates the amount of oil left in your tank according to the level on the dipstick.

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For a free publication on "Earthquake Energy Tips," call our Energy Hotline at 1-800-962-9731. Or, in Seattle, call 296-5640. The publication addresses the effect an earthquake - and its aftershocks - can have on your home utilities and heating system. You will learn how to be better prepared in such an emergency.

Home Clinic answers questions about home maintenance, repair and energy conservation. It is prepared by the Energy Extension Service, a division of the Washington State Energy Office. It appears Sundays in the Home/Real Estate section of The Times.