My heating contractor, Ralph Knowles, has converted me. I'm now a born-again believer that gas is the best way to heat the family home.

Our decision was based on several factors:

Natural gas in our area (near Boston) is, for now at least, more than 30 percent cheaper than oil, calculated on the cost per Btu.

[Natural gas prices in the Washington area and elsewhere could rise sharply as a result of President Reagan's plans to decontrol natural gas prices early, and heating bills for those who heat with gas could rise by as much as 50 to 100 percent, the Washington Gas Light Co. has said.]

The 40-year-old oil-fired boiler just removed from the house was inefficient by today's standards, even with a modern burner.

Gas was available on our street.

A new addition to the house, plus a modification of room use, required two new zones of heat.

We decided we couldn't afford not to decide for gas -- and for a new steam boiler.

How dramatic will the savings be?

Had we left the house at its former size, I calculate that the two changes -- the switch to gas and a new, efficient boiler -- would have saved up to 50 percent of our estimated annual fuel costs for 1980-81. That would be a saving of $650.

The savings might have been even higher, since we had the house fully insulated a year ago.

Heating a larger house now, I planned to save at least $325 a year, or 25 percent. Of course, the severity of the winter will be a factor, too.

My first gas bill, covering an abnormally cold month, indicated I am actually closer to the 50 percent savings figure. The insulation also has made a startling difference, apparently.

Such dramatic results require a sizable capital investment, varying in amount from one situation to another. But more modest efficiencies can be gained, also.

Meanwhile, we are saving national energy resources, as well.

The best-educated estimates about the trend of gas prices I have found add up to a set of related statements:

Gas prices already are going up steadily, but this is good in the sense that supplies also then go up.

Current gas supply in the United States is said to be quite adequate, according to both industry and federal government sources, even with the many new users.

The recent natural-gas scare in Boston looks more and more like an anomaly of unique proportions. The shortage reflected the coldest spell in more than a century (resulting in temporary laxity in conservation) and a sunken ship in an Algerian port. Also, two gas companies now are saying their request of years standing for a new pipeline into New England should be approved. State agencies now may reconsider past refusals in regard to more in-state gas storage facilities.

Present federal law would permit the cost of gas to catch up with the cost of oil by 1985, but the Reagan administration might try to accelerate the time factor.

Unless gas use goes up inordinately, no shortage seems to loom on the horizon. Geologists now are being quoted frequently as saying there is much gas still to be found in the United States. Higher prices spur increased exploration.

Many variables come into play in home heating:

Gas may or may not be available.

Some families have limited funds for new heating equipment and borrowing costs are high.

Some heat by hot air, some with steam and others with hot water -- or even combinations of the three.

Many conserve with wood or coal stoves or with solar systems. We added a fireplace insert that burns either wood or coal.

The amount of insulation and the efficiency of equipment in homes vary widely.

Some people are afraid of gas.

Heating experts often recommend that the first expenditure should be for adequate insulation, which can bring dramatic savings. The questions of fuels and more efficient equipment can be examined. Those who want to, or must, stay with oil can consider a better burner, a new boiler, an automatic flue damper or other changes that may be recommended by progressive heating contractors.

It also is possible to convert an oil boiler to gas without buying a new boiler. It is estimated that 1.5 million homes use gas for hot water but not for heating.

Most of them probably are only $700 to $900 away from gas heat, should they simply have a conversion burner put in their oil furnace.

Consumers, then, should first consider whether they have adequate insulation in their home. They can ask the utility company about an energy audit at little or no cost. Then they should decide whether they are using the fuel that is best for them and if it is possible to change fuels.

Finally, they need to consult local contractors about the efficiency of their present equipment and about how it can be upgraded or changed.

If they are interested in gas, they should talk to their gas company.

Automatic flue dampers and electronic igniters (for gas) are other energy-conserving innovations.

Both oil and gas boilers have undergone dramatic improvements in the last few years.

We learned that efficiency of equipment is a major factor in fuel savings.

Suppose someone bought a new oil boiler with an efficiency rating of 80 percent to replace an old oil unit with 60 percent efficiency.

(On May 19, 1980, a Federal Trade Commission rule took effect which requires all manufacturers of heating equipment to attach an "energy guide" label to their products. These labels give the efficiency rating of the equipment based on Department of Energy test procedures. The most efficient new boiler units use up to 85 percent of a fuel's Btu potential. Many old boilers are only 60 percent or less.)

This costumer with the new oil boilers wants to calculate his potential savings. He makes a fraction with 60 (the efficiency of the oil unit) as the numerator and 80 (the efficiency of the new boiler) the denominator.

This fraction can be reduced to 3/4. Then it is multiplied by fuel costs for the most recent year. An $800 real cost thus becomes an estimated fuel cost of $600 with the new equipment.