Damaged weather stripping can allow a lot of air to leak around old entry doors. Several surface-mount solutions work well to seal the cracks, but they're unattractive. A better-looking alternative is silicone rubber tubing weather stripping, available in several colors and diameters. Call Resource Conservation Technology (800-477-7724) for buying information. For a complete list of products and installation instructions, go to www.conservationtechnology.com/ building_weatherseals_caulkable.html.
Before you order the tubing, close the door and inspect the perimeter to see how large the gap is between the door and the frame. Measure and record the size of the gap at three places along both sides and at the top of the door. Use the chart at conservationtechnology.com to choose the right size tubing based on the size of the gap. Order different diameters for each side and the top if the gap sizes are different. If the gap varies along one edge, order progressively larger sizes and insert the smaller seal about 1/2 in. inside the larger seal where they join. You'll also need a tube of commercial-grade neutral- cure silicone caulk, which you can get from Conservation Technology. With the new silicone tubing in place, your old door will be as airtight as modern doors at a fraction of the cost of replacing the door and frame.