Torquay United lost their place in the Football League after a 1-1 draw against Peterborough at Plainmoor.
The Gulls will play in the Conference
Torquay had to win to have a hope of staying up, and they took the lead on half-time when winger Kevin Hill dived to head home from 10 yards.
But it was Andrews who conceded a penalty with a clumsy challenge on Jamie Day and Craig Mackail-Smith made no mistake from the spot.
Torquay pushed for a winner but Chris McPhee was denied by Mark Tyler.
The Gulls are nine points behind 22nd-placed Wrexham and 23rd-placed Boston with three games remaining.
However, Wrexham and Boston play each other on the final day of the season - ensuring that at least one of them is guaranteed to reach at least 43 points and ensure that Torquay cannot finish above 23rd.
Torquay: Rayner, Andrews (Angus 82), Woods, Robertson, Robinson, McPhee, Hockley, Mansell, Hill, Reid (Thorpe 69), Graham (Cooke 69).
Subs Not Used: Horsell, Dickson.
Goals: Hill 45.
Peterborough: Tyler, White, Futcher (Morgan 62), Blackett, Newton, Day, Strachan (Butcher 72), Gain, Boyd, Crow, Mackail-Smith.
Subs Not Used: Jalal, Blanchett, Smith.
Goals: Mackail-Smith 71 pen.
Ref: P Armstrong (Berkshire).