Q - The sun shines in one south-facing window and it really helps heat the room. Can I build some type of simple solar collector to mount on the outside wall next to the window to capture more solar heat? V. B.

A - You can build a simple and inexpensive solar heater that produces enough heat to warm one or two average-size rooms on a sunny day. By installing a small blower to circulate the room air through the solar heater, the heat output is greatly increased.When mounted vertically on an outside wall, a shallow solar heater, only about 5 inches deep, looks almost like another window from outside your home. You can also build it to be mounted horizontally or slanted out from a window for greater solar gain.

One very efficient and inexpensive design uses common steel or aluminum corrugated roofing panels for the internal absorber plate. When painted flat black, it becomes a very effective solar heat absorber. It also separates the room air from direct contact with the cold glass cover, so less of the solar heat is wasted.

A 4-foot by 8 foot solar heater is a good size because lumber and building materials are readily available. If you happen to have an old glass storm window or door, make it that size to avoid having to buy a piece of clear fiberglass or glass for the cover.

The basic design concept of a simple solar heater is that the room air enters in behind the solar-heated absorber plate. The corrugations in the absorber plate provide increased surface area for greater solar heat transfer to the room air. After circulating around the absorber and being heated, the air blows back out into your room.

You can use thin plywood and 1x4's for the collector box framing and construction if you mount it vertically against the house wall. The house provides support. If you mount it horizontally or slanted from a window, use heavier lumber for rigidity.

If you make it large enough, for example 4 feet by 8 feet, split the box lengthwise with another, slightly shorter piece of the framing lumber. This forms two long cavities and leaves a several-inch wide gap at the top.

Nail the corrugated collector plate pieces covering each half of the box. This forces the room air to circulate from the bottom inlet opening of one side, all the way up through the gap and back down the other side to the hot air outlet opening.

You can write to me for UTILITY BILLS UPDATE No. 379 showing do-it-yourself instructions, diagrams, and materials list for making this type of simple solar room heater. Write to James Dulley, The Deseret News, 6906 Royal Green Dr., Cincinnati, Ohio 45244. Please include $1.00 and a self-addressed STAMPED BUSINESS-SIZE envelope.

Q - I have an electronic air cleaner on my heat pump. Even when the heat pump is not running, I checked and the power is still on to the air cleaner. Is it wired correctly? T. C.

A - It generally is not wired that way. It is best to have it wired so it comes on with the blower. Although an electronic air cleaner uses only 40 to 50 watts of electricity, the wasted energy adds up over time.

Unless you are an experienced electrician, call a serviceman to rewire it. Since many heat pump blowers are 220 volts, make sure you supply the proper voltage to the air cleaner.