Keeping house warm -- for less -- takes some figuring

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 B.t.u.

* 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, now indicates 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, which I will mention later on.

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 then also go up.

* Current gas supply in the US 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 legislation 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 US. Higher prices spur increased exploration.

Given no gas cartel, given what seems to be a high supply curve, and knowing that some 90 percent of New England's fuel oil comes from the Middle East, I prefer the gas wagon to the oil "cart-el."

Obviously, each family's situation in regard to home heating is individual.

The reason is that many variables come into play:

* 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. Each situation is individual.

* 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. Then 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 is also 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 are probably only $700 to $900 away from gas heat, should they simply have a conversion burner put in their oil furnace.

Consumers, then, should probably 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.

Oil dealers understandably are not happy to see so many people changing to gas. The pro-and-con debate is bitter and almost impossible for the consumer to figure out objectively. He needs to consult his specific needs, goals, and wishes.

Mr. Knowles, our heating contractor, recommended a Weil-McLain steam boiler for our home, which required two new zones of hot water.

Most boiler manufacturers have done a great deal of engineering to produce more efficient equipment. One change has been to reduce the volume of water that is used in order to shorten the heating time. More efficient heat-transfer systems in the boiler have been developed as well.

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

Both oil and gas boilers have undergone dramatic improvements in the last few years. Boiler manufacturers and heating contractors could do much more to inform the public about these changes.

Weil-McLain has provided contractors -- who do the actual installation independently -- with an information kit that explains how to calculate for a customer the pay-back potential of new equipment, including the savings of a switch to gas if that is done. This manufacturer sells both oil and gas equipment, although the latter is selling more rapidly at this point.

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 utilize up to 85 percent of a fuel's B.t.u. potential. Many old boilers are only 60 percent efficient or less.]

This customer with the new oil boiler 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 with new oil boilers.

But suppose a consumer, in addition to a more efficient boiler, changes to gas which, in his area, is 25 percent cheaper per B.t.u. than oil. The $600 figure now is reduced to $450 for our consumer.

Usually it is best to talk with several contractors and obtain a range of prices and options. Ask a lot of questions. Stay with the situation until you have a feel for the variety of possible solutions that could cut your fuel bill. No two contractors will suggest the same set of solutions, if our experience is the rule. So be prepared to make some decisions on your own, based on your own sense of what is best for your home.

A good contractor should be flexible as well as informed. He will respect the right kind of input by the customer.