Concord took the lead midway through the first half as Dion Sembie-Ferris latched onto a through ball before curling a left-footed shot into the top right corner.
Josh Rees levelled before the break with an overhead kick before two goals in two minutes from Shaun Jeffers put the hosts in the ascendancy.
Steve Cawley revived chances of a comeback with his lobbed effort on 70 minutes but the Clarets restored their two-goal lead through Michael Spillane with ten minutes left.
Lyle Della-Verde scored the third goal for Concord after Rod Stringer and Anthony Church were both dismissed for the home side.
Bailey Vose’s terrific save on 20 minutes denied the hosts taking an early lead. The breezy conditions in Essex proved difficult for either side, with numerous passes ending off-target. However, Robbie Willmott spotted a free Elliott Buchanan who directed a powerful header downwards, although the Rangers shot-stopper managed to get a hand to deny the former Bishop’s Stortford striker.
The save proved incredibly important as minutes later the visitors took the lead. An inch-perfect pass from Taylor Miles met Sembie-Ferris’ run down the left wing, with the Colchester United loanee taking a touch before curling a shot beyond Ross Fitzsimons.
The wind continued to be influential but the Clarets managed to combat nature as Rees levelled the scores. Determination from Buchanan on the near-side won the hosts a throw-in, Chris Bush’s long throw picked out Rees turned the ball over the line with an acrobatic over-head kick.
The visitors had a perfect chance to take the lead in the second half when substitute Chris Dickson fouled a Concord defender. Miles flicked in the consequential free-kick and Cawley was on-hand but was only able to direct his shot past the post.
Adam Flanagan’s side was left to rue their miss as Robbie Willmott burst down the right wing. The winger teed up Shaun Jeffers who twisted and turned before rifling his shot beyond Vose.
The Clarets were then awarded a clear-cut penalty as Jeffers was wiped to the floor. Jeffers stepped up and calmly fired his second goal of the afternoon.
But the second half continued in quick fashion as the visitors went straight up the other end and scored. A poor back pass allowed Cawley to dart through before lobbing Ross Fitzsimons.
And a dramatic few minutes saw the Clarets reduced to ten-men, as well as seeing City boss Rod Stringer sent off. A soft challenge from Anthony Church saw the City skipper booked, which Stringer contested only for Whistler Aji Ajibola to dismiss him. Then, two minutes later, a late challenge from Church resulted in himself receiving his second yellow.
Nerves increased further when an 88th-minute goal from Lyle Della-Verde found the back-of-the-net with an effort from the edge-of-the-box.
The Clarets held on, however, to record an important win to propel themselves into the playoffs. Chelmsford are back in League action on Tuesday 28th February as they travel to Margate.
1. Ross Fitzsimons
2. Josh Hill
3. Bagasan Graham
4. Max Porter
5. Chris Bush
6. Michael Spillane
7. Robbie Willmott
8. Anthony Church ©
9. Shaun Jeffers (83’, off for Liam Enver-Marum)
10. Elliott Buchanan (56’, off for Chris Dickson)
11. Josh Rees
12. Chris Dickson
14. Mark Haines
15. Max Cornhill
16. Kane Haysman
18. Liam Enver-Marum
1. Bailey Vose
2. Robert Girdlestone
3. Ben Wyatt
4. Amos Nasha
5. Steve King
6. Taylor McKenzie
7. Dion Sembie-Ferris
8. James White ©
9. Taylor Miles (79’, off for Jordan Chiedozie).
10. Steve Cawley
11. Lyle Della-Verde
12. Sam Collins
14. Audrius Laucys
15. Jordan Chiedozie
16. Tony Stokes
17. Andrew Young
Chelmsford City: None.
Concord Rangers: Chris Bush (52’), Chris Dickson (62’), Anthony Church (83’).
Chelmsford City: Rod Stringer (84’), Anthony Church (85’).
Concord Rangers: None.
Chelmsford City: Josh Rees (40’), Shaun Jeffers (62’, 65’), Michael Spillane (81’).
Concord Rangers: Dion Sembie-Ferris (25’).
Half Time Score: Chelmsford City 1-1 Concord Rangers
City Man of the Match: Shaun Jeffers
Referee: Aji Ajibola.