Floor to ceiling drapes, or even drapes that puddle on the floor, add warmth and color to your room. But fabric touching heat registers could, at worst, create a fire hazard. At best, you could end up with all the heat from forced-air registers going behind the curtains, where it can't warm the room. If your heat registers are situated beneath a window, you have several options for dealing with the situation, depending on the type of heat register.
If you have baseboard heaters under your windows, you'll need to hem drapes at least 4 to 6 inches above the heater. These types of heaters are hot to the touch when operating. Letting your drapes cover these heaters creates a serious fire hazard. Even if you don't start a fire, you could end up with scorched and damaged drapes.
Forced-air heat registers blow warm air into the room from a central heating system. The air they blow isn't hot enough to burn you — you can comfortably place your hand on the heat register. If you have a cat, you may find he likes to nap on the heat register. This type of heat register won't set your drapes on fire if they come into contact with the register. But drapes can block heat from the register. When the drapes are drawn, heat blows up behind the drapes, which insulate it from the room. To prevent this from happening, you can purchase clear plastic diverters that mount on top of the heat register. These devices direct the hot air out into the room instead of behind the drapes. If you don't want to use one of these diverters, you'll need to shorten the drapes to the height of the window sill. The sill can then block the airflow from the register and prevent all the heat from being directed behind the drapes.
Length of Drapes
Shortening your drapes to 4 to 6 inches above the floor could result in an awkward look, as if the drapes shrank. If you can't let your drapes fall all the way to the floor, hem them to end at the windowsill or just below the apron. The apron is the wood trim beneath the windowsill. Hem all the drapes in the room to the same length for a uniform look.
If you don't like the look of shorter drapes, consider Roman shades or balloon shades. These provide the color and texture of fabric that can coordinate with your other furnishings but fit inside the window frame, so they won't interfere with the heat registers. If the register is centered under the window from, you may be able to have floor-length drapes, provided you keep them pulled back from the register at all times. Tiebacks and metal or wooden fixtures designed to hold the draperies out of the way can accomplish this and become a part of your window decor.