Complaints to 311 about heating problems soared as the temperature plunged below 20 degrees yesterday.

The city logged 2,110 calls by 5 p.m. as frigid temperatures made even sitting indoors unbearable for many.

That’s three times the number of calls the city got on New Year’s Day, when temperatures ranged from 33 to 46 degrees.

The figures do not represent the total number of homes without heat, as often, many tenants within the same building make calls.

Under city law, building owners are required to heat apartments to a minimum of 55 degrees when the weather outside dips below 40 degrees.