Crawley breezed into the FA Cup third round at the expense of Chelmsford.
Red midfielder Nicky Adams opened the scoring when his cross-shot crept in at the near post.
Blue Square Bet South side Chelmsford were reduced to 10 men when Donovan Simmonds picked up his second yellow, and Billy Clarke's volley made it 2-0 before half-time.
Gary Alexander's late penalty - awarded after Anthony Cook brought down Sergio Torres - put the result beyond doubt.
The visitors had keeper Stuart Searle to thank for keeping the score down, the former Crawley man saving well from Hope Akpan and Alexander in the second half.
VIEW FROM THE DRESSING ROOM
Crawley Town boss Richie Barker told BBC Sussex:
"I thought the players attitude was fantastic right from the first minute, they were excellent.
"The extra money in the next round would be great. Helping the football club with a big draw would make a difference to us.
"Over the last few years this club have had some decent ties, but we won't be getting too carried away yet."
Crawley Town 01 Jones 03 Sadler 04 Connolly 13 Hunt 28 Davis 06 Akpan (Bulman - 82' ) 07 Clarke (Akinde - 71' ) 08 Torres 11 Simpson 16 Adams (Jones - 80' ) 09 Alexander Substitutes 25 Kuipers 12 Walsh 19 Byrne 20 Wassmer 15 Bulman 21 Jones 17 Akinde Chelmsford 01 Searle 02 Brindley (Hamilton - 76' ) 03 Palmer 04 Miller 05 Hains 06 Cornhill 07 Cook Booked 08 Rainford 11 Welsh (Corcoran - 48' ) 09 Slabber (Edmans - 71' ) 10 Simmonds Dismissed after an earlier booking Substitutes 19 Wooton 12 Bender 18 Tann 15 Corcoran 16 Edmans 17 Hamilton 14 Calver