Choosing a preservative for a wood deck; information on wind power

Q Should we apply a preservative to a wood deck in Maine? Our concern is both the impact on the fragile environment as well as the welfare of the applicators. Another consideration is the cost of premature replacement of the decking. What do you say?

E. Patrick Coady Brooklyn, N.Y.

I most certainly would use a preservative on an exterior wood deck. Apply only one that has the approval and registration number of the Environmental Protection Agency. Follow the directions on the label.

Several national companies make stains that are either transparent or semi-transparent. If you want some color in the decking, try one of them. Your local paint dealer will have several types in four or more colors.

Without a preservative, you'll probably have to replace the decking far sooner than you might wish.

Q I am trying to find a reputable dealer who handles wind power, solar power, or both for the production of electricity. I live in an area of strong ocean-borne winds. Any ideas? Dr. Henry Haven Rancho California, Calif.

Check the various headings under ''solar'' in the index of your telephone Yellow Pages. Also, in the same index, look up ''wind chargers and machines,'' ''wind turbines,'' and ''windmills.'' That way you'll learn about some of the companies in your area that are involved in these subjects. In southern California there are hundreds of such listings.

By all means, verify the reputation of anyone you choose, since the solar and wind business is new enough to have many marginal firms doing business. The number of years in business is one criterion, of course. Another is sound feedback from lenders, contractors, better business bureaus, credit agencies, and satisfied customers.

Stay away from fly-by-nights if you want to avoid difficulties later on.

There is always maintenance involved in any mechanical apparatus. The future servicing of the equipment is an important aspect to consider when purchasing any new system.

For more information and perhaps a listing of members, get in touch with the following organizations:

* American Solar Energy Society, 1230 Grandview, Boulder, Colo. 80302; (303) 492-6017.

* American Wind Energy Association, 1516 King Street, Alexandria, Va. 22314; (703) 684-5196.

To the real estate editor:

In a recent column a reader from Charleston, S.C., asks what to do about fumes from a new furnace.

The answer in the Monitor leaves out the most important and necessary thing that needs to be done. With my years of experience with all types of oil burners , a great number of them having a problem exactly like that of the Charleston reader, I would like to suggest a simple answer.

First, proper burner adjustment. Cut the combustion air to the burner to a minimum. This relieves pressure in the combustion chamber and prevents particles of unburned fuel oil from getting into the hot-air ducts for some unknown reason. I say ''unknown'' because it takes very little fuel oil or vapor to cause an odor problem.

And second, the barometric damper in the stack may need balancing and adjustment. Samuel H. Thut Madison, Wis.

If you have a question on designing, improving, or maintaining your home, send it to the real estate editor, The Christian Science Monitor, One Norway Street, Boston, Mass. 02115. Forrest M. Holly is a longtime California builder now living in southern Arizona.