Heating was being restored for some residents of Liaoyang in the northeastern province of Liaoning on Friday, a power supplier said.
Homes in the city were left with freezing temperatures when a boiler failed at a local power plant on Tuesday afternoon.
However, heating was not being restored immediately to all 70,000 households, Hongyang Thermal Power in Liaoyang said.
"The boiler has been repaired and began to heat up on Thursday, but it needs time because the area is so large," said an officer at the power company. She could not say when heating would resume at all households in the city.
Bei Dianqiu, a resident in the city's Hongwei district, said radiators in his home are still cold. "The weather report said the temperature will drop tomorrow. I can't imagine how I can stay in the cold."