Look at the first four digits of the serial number once you find it.

Purchasing an older home with an existing furnace can be a worry; a furnace often needs replacing after 15 to 20 years, so knowing its age is helpful in determining if a new furnace should be in the budget.

Newer units may have a manufacturer's date listed somewhere on the furnace; older furnaces require a bit more digging by looking at the serial number, which tells the manufacturer various pieces of information, including the age.

One of San Francisco's great sights only takes place once a year during the cool and crisp days of winter at the Garden where nearly 100 towering magnolias, many rare and historic, defy the chill and erupt into a riot of pink and white blossoms.

The annual floral spectacle peaks between mid-January and March and tickets for special Magnolia Curator Tours and Magnolias by Moonlight are available now.

Turn off the power to the furnace -- by either turning off the power switch or the master fuse to the unit -- and look at the fan and fan blades.

Older furnaces sometimes had the serial number stamped onto the fan itself, giving the necessary information even when a manufacturing label is absent.

All rocks of Unit III experienced upper amphibolite- to granulite-facies and, locally, eclogite-facies metamorphism at 510–500 Ma.

The geologic features of Palaeoproterozoic tectonism in the Southern Terrane are very similar to those of the Australo-Antarctic Mawson Continent.

A comprehensive set of new geochronological data from different parts of the Shackleton Range in East Antarctica, comprising U–Pb single zircon and Th–U–Pb single and multi-grain monazite data, combined with published results, reveal a complex tectono-thermal history of the Shackleton Range.