Q - Sometimes when we use our wood-burning fireplace to help heat the living room, it does not draw well and smoke comes out into the room. How can we make it draw better? D. C.

A - A common cause of poor draw in a fireplace is improper design. Sometimes if the opening height is too large, just adding a narrow metal trim strip across the top of the opening can dramatically improve the draw. If a fireplace has good draw, it will not dump smoke into your room.There are many design dimensions that should be considered for a fireplace and the proper relationship among them is important. Most critical is the relationship between the opening width and height and the depth.

A rule of thumb is that the opening height should be between 2/3 and 3/4 of the width and the depth should be 1/2 to 2/3 of the height. You should follow FHA or your local code requirements for the size of the flue.

The height and position of your chimney relative to your roof and trees can effect the draw. A strong wind blowing in a particular direction may create a downward draft into your chimney. You can get chimney caps and wind deflectors to minimize the effect of the wind.

You should have your chimney checked and cleaned. Open fireplaces generally burn hot enough to minimize creosote buildup, but a bird or other animal's nest in the chimney may be obstructing the flow.

If you have an extremely airtight house, the smoke may be caused by an inadequate supply of air. Try opening a window in your living room and see if that helps. Also try to determine if it smokes more when the clothes dryer or kitchen or bathroom exhaust fans are running.

The best method to provide combustion air and to increase the overall energy efficiency of your fireplace is to provide outdoor combustion air. Without it, your fireplace draws heated air out of the rest of your house. The room with the fireplace stays warm, but the other rooms get chilly.

You can run a duct from outdoors under the floor to the fireplace. You should put a damper baffle in it or have a tight-fitting cover so you can close it off when there is no fire. If your house is built on a slab, just crack a window open a little in that room and close doors leading to other rooms. This reduce warm room air loss.

You can write to me for UTILITY BILLS UPDATE No. 277 showing a fireplace diagram and chart of ten significant design dimensions for opening widths of 2 feet to 5 feet, and a list of tips to use your fireplace efficiently.

Write to James Dulley, The Deseret News, 6906 Royal Green Dr., Cincinnati, Ohio 45244. Please include $1.00 and a self-addressed envelope.

Q - Our home is designed with the furnace ducts running through the crawl space. We have insulated the sides of the foundation wall. Should we insulate the floor above the crawl space too? T. N.

A - The additional energy savings from insulating your floor above the crawl space probably won't give a good payback. If the entire foundation wall is insulated, the uninsulated ground surface should not absorb a significant amount of heat.

Even though your crawl space is insulated, it would be a good idea to insulate any hot water pipes running through it. You also should have caulked around the sill perimeter where the walls rest on the top of the foundation. This is a common source of outdoor air leaking into your home.