Why do we smell oil when the heat hasn't been turned on for months?

August 7, 2007 2:02 PM

We have oil heat, but as you might expect in the middle of summer's dog days, we are not using it. So why do I periodically get a very strong smell of oil? This seems to have just begun in the last few days - at least I didn't notice it before. I checked the basement oil tank, no visible leaks and there is no strong smell down there. There have been no recent deliveries of oil that would explain this. Thanks for any help.
posted by mmf to Home & Garden (5 answers total)

Best answer: Your oil tank may have a pressure relief valve. The heat right now may be increasing the vapor pressure of the oil left in your tank enough to cause periodic venting, which you then smell.
posted by jamjam at 2:48 PM on August 7, 2007

Best answer: Or it might have a vent stack somewhere, with the increased hear you're probably getting increased vapor.
posted by iamabot at 3:06 PM on August 7, 2007

Some oil heat systems also supply hot water by a coil of pipe in the burner area, in a so called "tankless" system. This allows the system's burner to operate intermittently at least, year round, reducing seasonal start problems substantially. In that case, the combustion products from the burner firing intermittently for hot water may be more noticeable in hot weather, when the natural convective exhaust flue draft won't be as strong as it is in cooler temperatures.

Obviously, if your hot water is supplied from a separate tank, gas or electrically heated, you don't have this type of hot water service, but if you do, it might mean it is time to have the burner serviced, or the chimmney cleaned.
posted by paulsc at 3:10 PM on August 7, 2007

Just had a similar situation at my father's house last month. Also- no hot water. A quantity of water had found it's way into the oil line. It had rained like crazy a day before. When the call went for the burner to light, a mixture of vaporized oil and water was sprayed at the glow plug which could not light it. A strong scent of oil would hang in the air.
posted by pointilist at 9:20 PM on August 7, 2007

Response by poster: Thanks guys - the den window IS just above where the tank seems to vent and that's where we smell it.
posted by mmf at 9:40 PM on August 7, 2007