A solution to a vexing air conditioning problem at Miller-Driscoll School will be tested next spring and then should be fully installed over next summer.

Chris Burney, the town’s facilities director, explained to the Miller-Driscoll Building Committee on Nov. 9 that “after an inordinate amount of time in meetings and on conference calls” — some 100 hours — he, the design team, HVAC system manufacturer, contractor, and Turner Construction finally figured out why humidity levels were a problem in classrooms. In June, Burney said, teachers had complained about rooms feeling “stuffy.”

Essentially, he said, the cooling equipment operates efficiently, but when carbon dioxide levels rise with children in the classrooms, fresh air flows in from outside. On certain days, the air can be quite humid and the air conditioning, at set temperature levels, cannot adequately respond.

The solution, he said, is to install reheat coils for each classroom. Then, the air can be cooled for a longer period of time to negate any humidity and then be heated back up to a comfortable level. He said this is a standard practice and there is money in the contingency budget to pay for it.

“The problem does not happen in the area of new construction,” he said, “it’s in the renovated area.”

Forty-seven reheat coil units would be needed, one for each affected classroom.

“We don’t have a hard cost yet,” he said. “Dealing on instinct and experience we think it will be in the $300,000 to $400,000 range.”

Project manager Mike Douyard of Turner Construction said he would have hard numbers for the committee at its next meeting on Dec. 14.

The plan is to retrofit one pod — eight classrooms — over the April break and then the rest of the classrooms over the summer.

Several committee members asked why this was not addressed in the original design.

Burney cited a number of reasons, one of which was sensitivity to budget. Another system that was considered was a rooftop unit which would have meant lowering classroom ceilings to make space.

Complaints were made the first two weeks of June and Douyard said the problem was not solved over the summer because it was hard to mimic the conditions without children in the classrooms.

As to why this was not discovered in the design, architect Randall Luther said that when the system was originally presented “one of the cons was it didn’t have good humidity control but [the vendors] were surprised it would be as bad as it was.

“These coils are not a normal part of this system. That’s why we are where we are.”

In response to a question about whether the reheat coils would nullify any warranties he said, “the manufacturer of these units has to buy in 100% to this solution and we got confirmation they are on board.”

Douyard said that when students were out of school on Monday, Nov. 6, the HVAC foreman went to every classroom and looked above the ceiling to assure the units could be installed.

“The HVAC supplier won’t put any profit on the materials,” he said, adding if the units had been part of the original bid “you would pay about the same.”

Committee member John Kalamarides asked if there is recourse to go back to the vendor.

“Not really,” Luther said. “Their units meet the design criteria that’s in the specifications. … But when [the contractor] wrote our specifications for what it had to achieve, it achieved all those things. Maybe that spec is not as tight as we would like it to be, but we don’t think there’s any recourse with the vendor or the contractor.”

Burney said he presented this issue to the Board of Selectmen at its meeting on Monday and said he would find out if the town intends to hire a third-party engineer to review the problem.

Both Burney and Douyard said they were confident this solution would work. Douyard said they tried many software solutions over the summer but none of them worked, which led to looking at “a traditional fix.”

“If it works [in the pod] it will work everywhere,” he said in response to another committee member’s question. “This is a traditional way to solve this issue.”

Despite the expense for the reheat coils, Douyard said the estimated total project cost remains $36,574,755 after state reimbursement. The project completion date is Dec. 31.