A Hull man suffered third-degree burns over 35 percent of his body in a fire he said was sparked in a space heater shortly after midnight Sunday, according to a fire official. The man was taken by MedFlight to Brigham and Women’s Hospital. Efforts to extinguish the blaze took more than five hours as water from the firefighters’ hoses froze as soon as it hit the house, the fire official said. Firefighters were met with “heavy fire” when they arrived at the single-family house on Nantasket Ave., where the 62-year-old resident lived alone, at 12:05 a.m., said Captain Kevin Breen. The fire reached two alarms, summoning help from local departments. Firefighters had to break the waterfront home’s storm shutters to access the interior. One firefighter was taken to South Shore Hospital with a knee injury after he slipped on ice.