CRANSTON –– There are eight men crammed into Jimmy Cavanaugh’s tiny basement, and two of the biggest guys are now at the center of attention. They’re maneuvering a dolly holding a new steam boiler, a blue metal boxy device the size of a small freezer, which needs to go into the corner beneath an assembly of 2-inch heating pipes.

“Got a water line to your left,” one of them calls, as some of the men try to help. The others scramble to get out of the way.

Cavanaugh, 75, sits to the side and watches in amazement. “What an operation,” he declares.

Before the end of the day, plumbers will have it all connected and wired, ready to heat Cavanaugh’s two-story house as soon as the weather turns cold.

There was nothing wrong with Cavanaugh’s old steam boiler, which he had installed just eight years ago. But there’s a big difference between the two: the old one ran on oil, the new one burns natural gas.

Cavanaugh, a retired news-paper pressman and a former high school baseball coach, sums up why he was willing to spend $5,000 and have these men crowd his basement this summer morning.

“I just got sick of paying the damned oil bill.”

The prospect of $4-a-gallon heating oil this coming winter has spurred many Rhode Islanders to seek cheaper alternatives, and one of them is natural gas.

For years, the retail cost of heating oil was cheaper than gas, which helped make the fuel popular, especially in the Northeast. Of the 8 million households in the United States that use oil for heat, 6.2 million, about 78 percent, are in New England and the Central Atlantic states, according to the U.S. Department of Energy. In Rhode Island, about 42 percent of all households, or about 172,000, heat with oil, according to the 2000 U.S. Census Bureau. About 46 percent use natural gas.

But in 2006, the price of heating oil began a steady ascent that pushed it higher than natural gas. And last year, the price of heating oil rose dramatically, when global demand pushed up the price of petroleum-based fuels. Heating oil reached a high of $4.75 a gallon last month, 41 percent higher than it was a year earlier.

Over the past few weeks, the average price has subsided, falling to $3.93 a gallon yesterday, according to a weekly survey by the state Office of Energy Resources. Still, the price remains substantially higher than the equivalent amount of natural gas. At National Grid’s current rates, heating oil would have to cost $2.43 a gallon to equal an equivalent amount of natural gas, according to calculations by The Journal.

Even though gas is cheaper, the decision to switch may not be simple. Not everyone can convert because natural gas is only available in some communities, along some streets.

Then there are the conversion costs, which can run anywhere from $2,600 to $14,000, depending on the type of equipment needed and a heating unit’s efficiency rating.

“The higher the efficiency, the more it’s going to cost you, but the more you’re going to save,” said Tony Freitas, owner of JKL Engineering, a Providence heating and plumbing company. (Freitas was the FBI witness who helped convict former mayor Buddy Cianci and others of corruption charges resulting from Operation Plunder Dome.)

If there is not a gas line already running to the house, there are additional costs to pay National Grid to install one. That could add $800 or more to the total cost.

Those costs include rebates of up to $1,500 on equipment offered by National Grid. The current promotions have been extended until Oct. 15, according to a company spokesman.

At current prices of gas and heating oil, it could take years to recoup the cost of new heating equipment. For example, a typical gas customer uses 922 therms to heat a home over the course of a year at a cost of $1,615, according to National Grid. An oil customer who uses the same amount of energy would burn 666 gallons of heating oil and would pay $2,679 over the course of a year, according to calculations by The Journal. With annual savings of $1,064, it would take a little under five years to recoup conversion costs of $5,000.

Of course, that assumes that heating oil will remain more expensive than natural gas, which no one can predict with certainty. Heating oil prices could continue to drop, as they have over the past two weeks, and natural gas rates could rise, making the conversion less economically favorable.

The Public Utilities Commission is now considering a proposal by National Grid to boost distribution rates so the company can accelerate the replacement of unprotected steel pipes and cast-iron mains. The proposal would raise gas rates by about 5.1 percent.

Even National Grid is staying away from promoting conversions based on economics. Instead, its full-page newspaper ads and direct mailings to customers have highlighted the environmental benefits of switching, saying that heating with natural gas emits less pollution than the use of heating oil. (That claim is disputed by oil heat dealers.)

“To tell the customer that you should convert for price would not be fair if we find that price of natural gas goes up,” said David Graves, a spokesman for National Grid. “It may be close, at some point, to the price of oil.”

Nevertheless, more and more people are making inquiries and making the switch. Between January and June, there were 2,850 residential customers who called National Grid and expressed “serious interest” in converting their heating equipment to gas, Graves said.

During the same period, about 1,000 customers actually made the switch, he said.

About 30,000 households are in a better position than others to switch to gas. Those are National Grid’s “non-heating” customers –– those who already have gas piped to their homes and use it for cooking, clothes drying and other uses besides heating. They represent about an eighth of National Grid’s 245,000 customers.

A non-heating customer who decides to switch to gas for heat wouldn’t have to pay the utility company any additional cost to add service because a gas line already runs to the house.

“There’s an enormous amount of interest from people wanting to change from oil to gas,” said Jack Restivo, president of Restivo’s Heating & Air Conditioning, based in Johnston.

“The payback is definitely there,” he said. “Anybody that has age on their system and it’s just a matter of time to change it out anyway, those are the ones really benefiting by doing something now.”

That was John Vellucci’s thinking when he saw National Grid’s promotions. The Cranston resident said it was time to replace his old, inefficient oil-fired boiler, so he decided it was a good time to switch to natural gas.

Vellucci said he had heated with oil for years, and had grown very comfortable with his oil dealer, who provided reliable service.

But when his last oil bill arrived –– for $519 –– Vellucci decided it was time to switch. He spoke last week in his kitchen while plumbers from Phillips Plumbing installed a gas boiler in the basement.

“I needed a new boiler anyway,” said Vellucci, who owns a floor-covering company. “A lot of heat was just going up the chimney.”

A new boiler and hot water heater cost him about $5,500, he said. The boiler he chose is about 85 percent efficient. Some boilers are as high as 96 percent efficient, but cost substantially more.

Vellucci said his house already had natural gas service, which he and his wife use for cooking, so he was able to avoid installation charges for a gas line.

Cavanaugh, the retired pressman, said he’s not convinced he’ll save money with gas. But he wanted to switch because he thinks that the supply of natural gas will be more reliable than the source of heating oil. The majority of natural gas comes from North America, while most heating oil is made from crude oil imported from politically volatile regions of the world.

“I didn’t want to risk not being able to get it,” he said. “I trust the availability of gas more than I do oil.”

He said he didn’t like the smell of oil that would sometimes blow back into his basement from the chimney during windy days. He breathes with the help of an oxygen tank because of a respiratory condition.

The men in his basement were from two companies: JKL Engineering, the company owned by Freitas; and Boiler Busters, an East Providence firm that specializes in removing oil boilers and oil tanks.

Boiler Busters removed Cavanaugh’s oil boiler without trouble. But they couldn’t remove his oil tank because Cavanaugh had built shelves around it that held Christmas decorations.

The company workers will have to come back later after he’s torn down the shelves.