OGUNQUIT — A time-share resort where guests were sickened by carbon monoxide during the weekend won’t be fined, but it is planning to install carbon monoxide detectors in all 77 of its rooms, Ogunquit’s fire chief said Monday.

Twenty-one people at the InnSeason Resorts – The Falls at Ogunquit suffered carbon monoxide poisoning Sunday, and seven of them were hospitalized. Fire Chief Mark O’Brien said the four-building complex on Route 1 did not have carbon monoxide detectors.

O’Brien said the resort will not face any sanctions for not having the detectors because a state law requiring them took effect long after the resort was built more than 20 years ago. State records show that its current owner was incorporated in 2000 and the law took effect in 2012.

A state panel that oversees heating system installers is investigating the incident to determine whether the propane furnace that malfunctioned was installed properly in 2006, and whether it was maintained adequately.

“At this time, it doesn’t look like they’re going to be fined or anything, but there might be some violations,” O’Brien said. “Everyone’s searching hard to determine who serviced this and when it was serviced.”

Although there is no set schedule for inspections of hotel furnaces, business owners are responsible for having their heating systems serviced regularly to ensure they are operating safely and efficiently, said Doug Dunbar, spokesman for the agency that includes the Maine Fuel Board.

O’Brien said the odorless, colorless monoxide leaked into the basement of one of the resort’s buildings after a joint between two pipes that vent exhaust from one of two propane furnaces separated. The gas then spread to the 12 rooms above. The other buildings were not affected.

Air tests showed levels of carbon monoxide at 300 parts per million. A level of 35 parts per million triggers carbon monoxide detectors.

The building was almost full, and 30 guests in all were affected. The seven who were hospitalized were treated with high concentrations of oxygen and released by 5 p.m. Sunday. Fourteen were treated with oxygen at the scene, and nine had already checked out and gone home, O’Brien said.

Officials contacted the guests who had left and informed them of the diagnosis, but all declined to seek medical attention, he said.

Fire officials praised the quick thinking of the reception desk clerk who called the Ogunquit Fire Department after guests in two separate rooms complained of nausea. “That was a good heads-up call that probably saved a lot of people from really serious injury or death,” said state Fire Marshal Joe Thomas.

The resort did not release the clerk’s name, and told a Portland Press Herald reporter and photographer to leave the property Monday. The resort issued a statement saying that the affected building will remain closed until heating systems can be evaluated and repaired. The resort’s other buildings were tested and found to have no elevated carbon monoxide levels, the statement said.

After the incident, the resort’s staff got an estimate for the cost of carbon monoxide detectors and the total came to $3,500 for detectors for 77 rooms, O’Brien said.

“They just need board approval to approve the cost,” he said.

DETECTOR LAW HARD TO PASS IN 2012

Bob Jones, a guest from Vermont, arrived at the resort Monday for a week’s vacation. He said he had not heard of the incident and, when told about it, said it made him a little uneasy.

The time-share resort is classified as a hotel, said Thomas. By law, hotels that have been built or remodeled since Aug. 1, 2012, are required to have carbon monoxide detectors. InnSeason Resorts – The Falls at Ogunquit has not had any significant renovations since that date, O’Brien said.

Former state Sen. Bill Diamond of Windham, the law’s principal sponsor, said it should have applied to all buildings, “but believe it or not, we had a very hard time getting this law passed.”

Diamond, who left the Legislature in 2012 because of term limits but plans to run for the Senate in November, said the Legislature’s Criminal Justice and Public Safety Committee faced fierce opposition from the construction, real estate and tourism industries because of the cost.

“We had to give in, to get something passed. It always seems to come down to that: money,” he said. “But when you measure that against peoples’ lives, it’s hard to justify. This (incident in Ogunquit) could have been a major disaster. Everyone should have a detector in their home.”

PUBLIC MORE AWARE OF RISKS

According to the National Conference of State Legislatures, 25 states have laws that require carbon monoxide detectors in certain residential buildings. Connecticut and Maryland require carbon monoxide detectors in schools. Texas requires carbon monoxide detectors in certain day care centers, group day care homes and family homes.

John Martell, a Portland firefighter and president of the Professional Fire Fighters of Maine, said the laws governing detectors vary widely from state to state.

His organization lobbied for a law in Maine that would have applied to all buildings, but he said the opposition was too strong. That might change in the next legislative session, he said, as public awareness of the dangers of carbon monoxide poisoning grows.

On Saturday night on Long Island in New York, one man died and 26 people were treated for carbon monoxide poisoning at a restaurant. Investigators found that a leak in a water heater flue pipe caused the gas leak.

In Ogunquit, “We were fortunate this time that no one died,” Martell said. “Unfortunately, it usually takes some type of tragic event to change things.”

The resort was researching its maintenance records Monday to determine the last time the heating system was serviced, but had not found them, O’Brien said. The problem could have been detected with regular maintenance, he said.

On Monday, he said, the fire department fielded calls from people planning vacations in the oceanfront town who wanted to know whether their hotels have carbon monoxide detectors. He suggested not leaving it to chance.

“If people aren’t comfortable and don’t know, buy and pack a battery-operated one, take it out of the luggage and throw it on the night stand,” he said.

Staff Writer Dennis Hoey contributed to this report.

David Hench can be contacted at 791-6327 or at: dhench@pressherald.com