Snow pleaded no contest to reckless homicide charges. He faces up to 20 years in prison when he's sentenced next month.
Snow dropped off the generator on March 22 during a cold snap and found the bodies of the 39-year-old woman and her three children the next morning.
He told The Associated Press on the day of his indictment that he didn't know the family planned to stay in the house overnight and he gave them the generator to warm the place up temporarily.
"All I was trying to do was to give them a better house and a better place," he said.
Snow's attorney, Scott Schwab, wouldn't discuss why Snow decided to change his plea. Schwab said there was no deal with prosecutors on a possible sentence.
Snow had known Tamara McDaniel for two decades and said he thought of her and the children as family.
McDaniel; Damien Reyes, 18; Domonique Reyes, 16; and Taralynn Wood, 10, were found on the first floor in the same room. It didn't appear as though they had been trying to escape, police said.
A coroner ruled all four died of carbon monoxide poisoning.
Each year, about 180 deaths in the U.S. are linked to carbon monoxide from appliances and small engines, like those in portable generators, running in enclosed spaces, according to the Consumer Product Safety Commission. The Centers for Disease Control and Prevention estimates several thousand more are treated for carbon monoxide fumes at emergency rooms.
Nearly half of all states now have laws requiring property owners to install detectors for the deadly gas.