4:07 p.m. CDT, July 21, 2011

Hotel workers on strike at the Park Hyatt were taken by surprise Thursday morning when 10 heat lamps hanging above their picket line flipped on and stayed on for nearly an hour.

"This is one of the hottest days of the summer," said Daniel Medina, 42, a bellman at the Park Hyatt for two years. "I work at that door every single day and only in winter time do those need to be turned on. Somebody did it on purpose. It's ridiculous."

Hyatt said in a statement that as soon as they were alerted to the fact that heat lamps were on under the awning of the hotel's Chicago Ave. entrance, they turned them off and handed out water.

Medina said the lights do not turn on automatically and that only bellhops, doormen and engineers access the room that controls the heat lamps. He said there was no way it could be inadvertent.

It was 83 degrees at 7 a.m. Thursday, according to the National Weather Service.

The hotel workers at the 800 N. Michigan Ave. hotel kicked off the day-long strike Thursday morning to protest the working conditions of housekeepers. The strike coincides with housekeeper protests at Hyatts in nine other cities in the U.S., said Unite Here Local 1, and 22 months of stalled contract negotiations with Hyatt in Chicago.

After Hyatt allegedly turned the heat on the strikers, Gabriel Carrasquillo, a server at the hotel's restaurant NoMI, began to chant, "You can't smoke us out," and extended the picket line beyond the heat lamps so that employees could get periodic breaks from the heat, he said.

In a statement, Hyatt called the strike "more of the same from Unite Here" and said the union "continues to put its energies toward unproductive street theatrics in the name of 'solidarity.' "

"In cities from Chicago to Waikiki and here at Park Hyatt, we have offered union leaders contract proposals that match wage and benefit packages identical to what Unite Here has accepted from other hotel companies," the company said. "Yet, union leaders have rejected every one of these proposals."

The Chicago-based hotel chain is the last holdout in the city. Hilton's unionized hotel workers approved a four-year contract in March and two months later, Chicago hotels owned by Starwood reached a settlement with the union, affecting 1,200 workers, bringing along an additional 16 other hotels representing 2,000 workers who piggybacked on the Starwood contracts.

The Hyatt negotiations have been the most contentious, punctuated by protests and religious leaders pledging to boycott the hotel chain. In its attempts to negotiate a deal, Hyatt even posted a video on YouTube urging employees to accept its contract offer.