Police alerted the owners of Border Heating and Cooling about the incident on Thursday after learning that the woman had moved to Wodonga from Melbourne.

She failed to alert the company that she had moved from Werribee before two technicians undertook work on her heater.

The incident forced the business to close for several days and cancel upcoming jobs as 10 staff members and some of their family members isolated and awaited coronavirus test results.

Owner Karen Pitteri said all tests had so far been negative, but said she was "really, really angry" at the situation.

"We've got screening questions but she didn't disclose it," she said.

"We've had to stop work immediately and have lost income.

"We've had a whole weekend spent sitting at home and jobs have been cancelled, just because someone did the wrong thing."

Some staff will return to work on Monday but some are yet to receive their results.

Ms Pitteri said about 20 jobs had been cancelled.

"Her actions are selfish and ignorant," she said.

"We were just trying to do our job and she had no regard for the impact it would have.

"We've all tested negative and we've maintained good practice throughout, but this is just disgraceful."

The woman and workers hadn't shown any symptoms.

A Werribee school was forced to close late last week after a student tested positive and others in the region have tested positive.