LEWISTON, Maine — Six months after breaking ground on a $2 million expansion, Baxter Brewing Co. is moving into a newly remodeled corner of the Bates Mill and producing more beer than ever.

Since three new 8,000-gallon fermenters were installed this spring, production has increased from about 8,000 barrels per year to 15,000 barrels. The canning line has sped up to one can per second. And, in December, three more equally huge fermenters will be installed, effectively doubling production again.

Yet the 3-year-old beer company is still unable to keep up with demand, according to Luke Livingston, the company’s founder and president.

“In the old days, we’d maybe package 85 barrels,” Livingston said. “This week, we packaged 185 barrels of beer. We’re getting a little closer than we were, but our total orders for this week are still more than 600 barrels.

“It beats the alternative, but it’s still tedious,” he said.

The growth will help.

Livingston couldn’t help but smile when he walked through the plant Thursday, proudly talking about the 2 miles of rebar that reinforce the new fermenters’ concrete base and the new windows that were installed in his corner of the Bates Mill complex.

“Three years and $4 million later, I finally have an office with a window,” he said.

Livingston and his staff had worked for the company’s first years in a bricked-up area one floor below. Since construction began in January, work on the new upstairs offices unearthed decades of dust, which sprinkled down to the workers below, including Livingston and his wife, Chelsea, who serves as the company’s business manager.

By contrast, the new space resembles a modern office, with new interior walls and fixtures, furniture and carpeting. There are storage rooms, private meeting spaces, a conference room and an employee kitchen outfitted with all the usual amenities … plus two beer taps.

It’s also well lit, a particularly big feat considering that previous windows were bricked up at least 50 years ago. Workers carved out new casings and installed new panes with a view of those prize fermenters.

“They knew we’d appreciate the view,” Livingston said.

The brewery plans to host a four-hour open house beginning at noon Sunday. There will be tours, games, music and food. There will also be a chance to taste Baxter’s marquee brews as well as some experiments.

Several beers were being served in the tap room Thursday, including a concoction called “peachy-keen.”

“There’s a pretty constant stream of test brews here,” said Ben Low, Baxter’s director of brewing operations. “A lot of it is just to be fun and creative,” he said. “We have at least one new brew here per week”

Livingston hopes it will entice more people to visit the tap room.

Meanwhile, his focus is on production.

When the new fermenters are installed in December, production and processing will surge to a 24-hour schedule. Hiring will increase, too.

“We’ve hired six people this year,” Livingston said. “We have a staff of 16 now, and I expect we’re about halfway there.”

With them, he hopes to meet more orders coming from Maine and Massachusetts.

“I get calls on a weekly basis from distributors,” he said. “I have to tell them, ‘We can’t get to Montana before we get to New Hampshire.’”

Worse are the calls that come from a short walking distance away. He recently had to delay an order to Fish Bones American Grill, he said. When the call came, he didn’t have any stock of the requested Stowaway I.P.A.

“He’s right there and I can’t give him any,” he said. “That hurts.”