If you're thinking about installing storm windows to help you cope with rising heating costs, you'll be glad to know that some of the cheapest types are also the best performers. I'm talking about the do-it-yourself storm window kits that have become popular over the past few years.

The reason for their excellent performance is simple. Unlike conventional combination storm window-screens, these kits let you cover your entire window with a single sheet of glazing material. There are no gaps between panels or glass, no loose sliding joints to leak chilly drafts. As a result, the single-pane kits have been shown to cut infiltration of cold air by over 90 percent in tests on actual homes. By contrast, combination storm windows reduced infiltration by less than 35 percent.

These storm-window kits come in various types, but typically consist of a lightweight frame material of aluminum or plastic. Sometimes the frames are cut to size, sometimes you cut them to size yourself, using ordinary hand tools. Then you add glazing (usually clear acrylic) and put the windows up. All can be applied to the inside of your present windows, and some can be installed either indoors or out.

Indoor installation is slightly less appealing in terms of aesthetics, but it has certain advantages: Installation is easier and safer since you don't have to climb around on ladders. That advantage becomes even more important on second- and third-floor windows. Inside installation also makes for easier cleaning and removal for the summer if desired.

A further bonus: You can install these storm windows indoors even if you already have outside storm windows. This will give you the triple glazing recommended for extremely cold climates.

Here's a quick rundown on some of the major brands of storm window kits:

IN-SIDER is probably the best known. It fastens to your interior window trim by means of adhesive backing on vinyl frame material. If you want to remove the glazing for the summer, the frame snaps open. The In-Sider is made by Plaskolite, Inc. P.O. Box 1497, Columbus, Ohio 43216.

THE BARRIER is another system using self-adhesive vinyl framing. In this case the frame snaps apart to release the glazing for summer removal or for cleaning. K.S.H., Inc. 10091 Manchester Road, St. Louis, Missouri 63122, makes it.

THERMA FRAME also uses vinyl faming members, but you install the frame by screwing plastic turnbuttons to your window trim, then locking them over the frame. Unlike the two adhesive-mount systems above, this one can be installed outdoors as well as in. It's from Elgar Products, Inc., P.O. Box 22348, Beachwood, Ohio 44122.

THERMATROL Stock-Line windows come cut to size, with acrylic glazing. You can buy them in a one panel design, or in a two-panel design. The two-panel type lets your remove the lower pane for glazing and clip it to the upper one for vetilation. Perkasie Industries Corp., 50 East Spruce Street, Perkasie, Pennsylvania 18944, makes it.

MR. WINDOW also uses precut frame parts, but these are aluminum instead of plastic. Glazing is secured with a removable plastic spline that will also hold screening in place of glazing. Installation is with turnbuttons, indoors or out. It's from Aluma-Trim Inc., 918 Stanley Avenue, Brooklyn 11208. Q: I'm getting ready to pour a concrete patio off the back of my house. Right now I can't afford to cover it, but some day I hope to. Is there any way to provide some means of anchoring the posts I'll need to support the roof? I don't want to set anchor bolts now since they'd be a hazard sticking out of the concrete . A: One simple idea I've seen is to wrap a coffee can with corrugated carboard and secure with tape. Place the can where you want to anchor a future post and secure it with a large spike through the bottom of the can into the ground. Position the can so its top level with the tops of your concrete forms or above them.

Pour your concrete and finish it off as usual. Then, after it has set but while it's still somewhat soft or "green," remove the can. This will create a pocket in the slab. Whenever you're ready to build your patio cover, fill the pocket with ordinary concrete or a patching mix and set your anchor bolt as usual.

In the meantime, keep the hole filled with sand or use it as a small planter so nobody will step in it and turn an ankle.

One last tip: Put the hole no closer than six inches from the edge of the slab. If you put the hole too close to the edge, strength will suffer.