A contractor who hooked up homes in the suburbs north of Portland to natural gas has gone out of business, leaving an undetermined number of customers who had paid in advance to have their home heating systems converted without apparent recourse to recoup their investment, according to municipal and business officials.

Most of the customers affected by the sudden closure of Dave Ireland Builders LLC of Howland live in Cumberland. Some of the customers live in Falmouth and Yarmouth.

Cumberland Town Manager William Shane posted a message on the town’s website Sunday addressing “the sudden disappearance” of Dave Ireland Builders. Town officials learned about the company’s situation late last week.

Shane encouraged homeowners who paid in advance to have their home heating systems converted to natural gas to file complaints with Summit Gas and the Maine Attorney General’s Office.

Shane said he is also consulting with the town’s attorney, its police chief and the Cumberland County district attorney.

“This individual company has caused a lot of damage to potential future conversions and I am urging Summit to step up to help in some way,” Shane wrote. “I believe the more information that is shared the closer we can bring this to a better resolution for all.”

Dave Ireland did not respond to a message left Sunday night on his cellphone or to an email seeking comment. His website says Dave Ireland Builders has more than 19 years’ experience in the building industry, having completed projects all over New England, from Fort Kent to Rocky Hill, Connecticut.

“We are not only proud of our Better Business Bureau Accreditation, but we are pleased with a our A+ rating,” the company’s website says.

Summit Gas is an Augusta-based company that supplies natural gas to Maine homes and businesses. The company has already installed 238 miles of natural gas infrastructure in Kennebec and Cumberland counties, a market that holds the potential to serve more than 7,200 customers, according to Mike Minkos, the president of Summit Gas.

Minkos said Sunday night that he found out late last week that Ireland’s company had gone out of business. He said he is not sure if Summit Gas can help those customers left in the lurch. Minkos described Dave Ireland Builders as one of many contractors that are available to convert a home’s heating system to natural gas.

It is up to a homeowner to choose an installation contractor, not Summit Gas, according to Minkos.

“We are a utility company. We put the lines in the street,” Minkos said. “We remain hopeful that customers will go ahead with their conversions. Unfortunately, some customers may lose money, but we still want them as customers.”

Shane, the town manager, said in an email Sunday night that Ireland started out doing energy audits and air sealing in area homes – work that he expanded to include furnace installations and conversions to natural gas.

Jason Lamb, a Windham plumbing and heating contractor, became Ireland’s “partner or subcontractor for the conversion side,” Shane said.

Shane said Summit Gas obviously wanted to encourage conversions and was encouraged that Dave Ireland Builders charged about 15 percent to 20 percent less than most contractors in the area.

Shane said many people in his neighborhood in Cumberland used Ireland and were happy with the system that he and Lamb installed. Shane said Lamb did the installations and Ireland handled the financial side of the business. Ireland required upfront deposits ranging from $1,500 to $3,000 depending on the type of heating system, according to Shane.

Shane and Minkos could not specify how many homeowners may have paid Dave Ireland Builders in advance, but Lamb said Sunday night it could be as many as 200.

“We are all trying to play catch-up right now,” said Shane, who plans to update members of the Town Council on the situation Monday night. The meeting will start at 7 p.m. in Town Hall.

Lamb said he found out Tuesday that Ireland had gone out of business. Until last week, Lamb served as Ireland’s subcontractor, whose job was to visit prospective customers’ homes for pricing the cost of a natural gas conversion.

“(Ireland) told me that he had been talking to his lawyers about shutting it down,” Lamb said, referring to Dave Ireland Builders. “I don’t know what happened other than that there are a lot of angry people.”

Lamb said he had nothing to do with customer deposits. But he felt compelled to send a letter to Cumberland residents in which he told them that Ireland is no longer doing business. His letter was posted on the town website along with Shane’s letter.

“Dave Ireland Builders has abruptly closed its doors as of this week,” Lamb wrote. “So with no notice, myself, as well as my co-workers were left jobless. I no longer have any affiliation with his company or with Dave Ireland himself. … I certainly do not conduct business like my former employer and I apologize for those of you who have been affected by this.”

Lamb said that of the estimated 200 conversion contracts, only 35 jobs have been completed. He said nearly all those customers live in Cumberland, Falmouth or Yarmouth.

Shane said customers should not give up hope.

“I hope with all of us working together we can recover some or all of the monies invested by the families of Cumberland,” he wrote on the town’s website. “This is a lousy way to start (off) the holiday season, but I think we need to exhaust all legal avenues collectively as a group first.”