Hot weather, heavy use of energy and one more shutdown of a large coal-fired power plant contributed to thousands of Xcel Energy customers losing control of their thermostats for a short time at the end of August.

The third unit of the Comanche coal plant in Pueblo lost power due to a leaking tube on Aug. 30, Xcel Energy-Colorado spokeswoman Michelle Aguayo said in an email. Comanche 3 was repaired and began operating again Sept. 2.

Built in 2010, Comanche 3 was out of commission for most of 2020 and for several months earlier this year. The serially troubled coal-powered unit averaged 91.5 days per year of outages over a decade, according to a 2021 report by the Colorado Public Utilities Commission.

The latest outage resulted in Xcel AC Rewards customers losing control over their smart thermostats on Aug. 30 when temperatures were above 90 degrees. The program’s voluntary participants allow the utility to control their thermostats when hot weather drives up demand for electricity.

Customers can usually regain control of their thermostats at any time, according to Xcel. Company officials called the recent lockout a unique circumstance.

More than 22,000 Xcel AC Rewards customers were locked out of their smart thermostats for several hours, Denver7 reported. Xcel customers took to social media to complain about their hot houses.

Aguayo said the breakdown at Comanche 3 coupled with the hot weather, high energy use and the limited ability to buy more energy on the spot market due to a heat wave in the West is why Xcel activated the AC Rewards program.

Xcel Energy, Colorado’s largest electric utility, plans to close Comanche 3 by Jan. 1, 2031. Environmental and community activists have argued for an earlier closure because of the financial and environmental costs.

Xcel Energy originally planned to run the coal unit until 2070.

Denver Post reporter Kieran Nicholson contributed to this report.