Windowizards resumed operations Monday, with the Bucks County replacement-window sales and installation firm blaming delayed shipments from a supplier for its abrupt shutdown Thursday.

"That situation has now been resolved," Harvey Goodman, chairman of the 50-year-old Levittown company, said in a statement posted at www.windowizards.com.

"There are absolutely no plans to close our business," Goodman, 70, said. "We intend to honor all commitments to our customers, installers, and employees," who were urged to call the company at 1-800-220-8707.

Efforts to contact Windowizards by phone for further comment were met with busy signals throughout the day.

The supplier was not identified by Windowizards, which deals with several of them.

In the last three months, there has been enormous demand for energy-efficient replacement windows among homeowners hoping for a federal tax credit of 30 percent of their cost, up to $1,500. (The credit is part of the government's 2009 American Recovery and Reinvestment Act.)

Vic Spear, vice president of Simonton Windows, said the Parkersburg, W. Va., manufacturer had had strong "pull-ahead" orders during the fourth quarter of 2010.

"We believe some people who were originally planning to purchase replacement windows during the first part of 2011 are ordering them now to take advantage of the final days of the federal tax credit," Spear said, adding that his company had been able to keep up with the demand.

Simonton does not appear on the list of Windowizards' suppliers.

For homeowners to qualify for the tax credit on their 2010 returns, replacement windows must "placed in service" by Dec. 31. The Internal Revenue Service defines that as "not when you purchase the product, but the day the installation is complete, and you are able to use it."

Last week, the law covering tax credits for energy-efficient retrofits was extended through 2011 but was limited to $200 for windows.

On Friday, the Bucks County Consumer Protection Office received complaints from several dozen Windowizards customers who had placed deposits for work.

The head of the office, Mike Bannon, said that Goodman had assured him customers' contracts would be honored, and that Windowizards had a good reputation.

Monday's statement from Goodman said that the company would begin contacting its customers "over the next 24 hours," and that it planned "to ensure that all work scheduled for completion is accomplished in a timely manner."

"We deeply regret any anxiety, discomfort, or concern that our company has caused regarding this matter," Goodman said in his statement.

Contact real estate writer Alan J. Heavens at 215-854-2472, aheavens@phillynews.com, or Twitter: @alheavens.