TULSA, Okla. (AP) — Rooftop air conditioner and heater maker Aaon Inc. plans a massive expansion that could eventually double its 1,000-employee work force.

 

President and CEO Norman Asbjornson said he cannot yet put a dollar figure on the cost of the expansion at the company's Tulsa headquarters, but Aaon has said it will spend $5 million on a new, 150,000-square-foot building for assembly, testing and unloading room and another $50 million on additional machinery.

 

Over the next 10 years, Aaon plans to add more than 600,000 square feet of manufacturing space and 1,000 employees. Eventually, the company hopes to triple its production lines from two to six and add 12 more sheet-metal fabricating machines for a total of 20.

 

''This is a long-term makeover,'' Asbjornson said. ''We'll do double and possibly triple in the volume of products made.''

 

Aaon has been growing steadily during its two decades under Asbjornson. Sales reached an all-time high of $262 million, 13 percent higher than 2006's record of $231 million, according to an earnings report released this week.

 

The biggest growth has been in its giant rooftop heating and cooling units and water chillers, mainly made in Tulsa. Coil and residential units are made in Longview, Texas, and some custom products are made in Canada.

 

The company is confident in continued growth in heating and cooling new industrial and commercial buildings, and it also wants to broaden its business in residential unit and parts markets.

 

''We're in a better position now than we've ever been to continue our growth,'' Asbjornson said. ''We'd better figure how to build on it.''

 

Aaon's leadership has been working on the expansion plans for two years, thinking of ways to be more efficient with production, engineering and testing and how to improve its administration.

 

The company still must figure out the logistics of shift changes with so many new employees and whether roads around its west Tulsa operations will need changes.

 

''We don't have answers for all of this,'' Asbjornson said.

 

What Aaon does know is how it will pay for the expansion.

 

''We're totally debt-free,'' company marketing manager Sam Neale said. ''The expansion will be paid for totally out of cash flow.''