Successful companies make investments that pay off. And judging by that standard, one long-time Rhode Island manufacturer has been making some very successful investments.

Taco Inc., the nearly century-old Cranston-based maker of heating and cooling systems, has seen its revenue grow from $30 million to $200 million in the last few decades, allowing it to maintain its workforce of 500, a trick not many companies have managed in the face of improving productivity and increased global competition.

One key to Taco’s success has been the time, energy and money it has spent on its employees, with its latest investment the recently opened Innovation & Development Center.

The $20 million, 24,000-square-foot addition to the company’s factory includes laboratories, a business center and classrooms. And it is the last piece that deserves special note.

Many companies invest in the latest technology or to develop product-line extensions. And Taco can count itself among that lot. But it has done more.

Company President John H. White Jr. notes that Taco began investing in employee education long before it was in vogue. He credits many of the productivity gains made by the company to its people, many of whom have been there for a long time.

For instance, Taco experiences 1 to 2 percent turnover per year, well less than the national average of 14.4 percent, according to the Bureau of National Affairs. The average length of service for a Taco employee is 17 years, a lifetime by today’s standards. And a sign that the company is doing something quite right. •