The visitors took an early lead when Matt Saunders volleyed in James Kaloczi’s cross and Saunders then doubled Hemel’s lead with a superb free kick from 35 yards.
James Potton looked to have wrapped up the win early in the second half with a delightful lob over Ross Fitzsimons before Chelmsford rattled off four goals in 15 minutes to turn the game on its head.
The introduction of Shaun Jeffers saw the striker tap in a Bagasan Graham cross before scoring against from the penalty spot after Aaron Hayden had handled in the area.
Then two goals in the space of a minute completed the turnaround. City’s equaliser came from a Robbie Willmott cross that was bundled over the line before Shamir Mullings burst through to slot past Jamie Butler.
Chris Bush was shown a red card for over celebrating the goal in front of the Hemel bench and in injury time Luke Daley brought down Sam Corcoran in the area, with Parkes levelling it up.
The draw maintains Chelmsford’s unbeaten run which extends to 10 games, but Rod Stringer was far from happy with what he saw as a lack of discipline from his players.
The visitors came to Melbourne Park off the back of a disappointing cup defeat in midweek to Taunton Town but they took a shock early lead through Matt Saunders.
In just the third minute of the game James Kaloczi picked out Saunders in the area, with the midfielder caressing the ball into the back of net on the volley to put the visitors in front.
Chelmsford were struggling to create anything of note and their afternoon went from bad to worse when Saunders grabbed his and Hemel’s second of the game from a free kick.
After Kaloczi was barged in the back Saunders ripped his free kick from 35-yards past Ross Fitzsimons to double the visitors lead.
Chelmsford failed to really get going but did go close from a corner when Robbie Willmott’s cross found the head of Shamir Mullings who sent the ball inches over the bar.
It was a frustrating half of football for the Clarets which was compounded by Mullings picking up his fifth booking of the season which means he’ll be suspended for next weekend’s trip to Concord Rangers.
Chelmsford came out in the second half looking for an early goal to get them back into the game and they almost were giving a helping hand when Tony Diagne almost beat his own goalkeeper with a header back.
The third goal of the game was always going to be crucial and it was the visitors who got it, all but killing the game off in the process.
A free kick from Butler was beautifully brought down by James Potton, and with his second touch he looped the ball over Fitzsimons with the outside of his boot to make it 3-0 to The Tudors.
Chelmsford had a mountain to climb if they were going to make it 10-games unbeaten in the league and they almost fell further behind when Kaloczi’s shot on the turn was tipped round the post by Fitzsimons.
City came very close to getting one back when Chris Bush muscled his way into the area picking out Josh Rees whose glancing header went inches wide.
But the Clarets did manage to get themselves back in the game when substitute Shaun Jeffers tapped home from close range after being found in the area by a low cross from Bagasan Graham.
The goal lit a fire in Chelmsford and they were thrust right back in with a chance of turning this around when Aaron Hayden handled in the area, giving away a penalty.
Jeffers, who had only been introduced about 10 minutes previously, stepped up and sent Butler the wrong way to put the Clarets within a goal of the visitors.
Chelmsford were now well and truly on the front foot and went within inches of equalising when Mullings barrelled his way through a couple of challenges sending his shot flying just over the crossbar.
Well in the ascendency Chelmsford completed the turn around by scoring two goals in the space of a minute to go from 3-0 down to 4-3 up.
City’s equaliser came when a free kick from Robbie Willmott was flicked on before being bundled over the line and less than a minute later the Clarets took the lead when Mullings ran clean through and slotted the ball beyond Butler.
In the celebrations Bush was shown a second yellow card having picked one up earlier in the half for over celebrating in front of the Hemel Hempstead bench meaning City had just over 10 minutes to hold on to their lead with 10-men.
It looked like the Clarets were going to get across the finish line but in added on time Luke Daley was adjudged to have brought down Sam Corcoran in the area with referee Elliot Kaye pointing to the spot.
Jordan Parkes stepped up confidently to send Fitzsimons the wrong way from the penalty spot to ensure that having been 3-0 up Hemel would at least not go home empty handed.
1. Ross Fitzsimons
2. Matt Young
3. Chris Bush
4. Josh Rees
5. Adam Bailey-Dennis
6. Phil Walsh
7. Robbie Willmott
8. Max Porter
9. Shamir Mullings
10. Billy Bricknell (C)
11. Bagasan Graham
12. Shaun Jeffers (On for Billy Bricknell 55’)
14. Anthony Church (On for Matt Young 55’)
15. Luke Daley (On for Josh Rees 82’)
16. Max Cornhill
18. Frankie Merrifield
Hemel Hempstead Town:
1. Jamie Butler
2. David King
3. Kyle Connolly (C)
4. Jordan Parkes
5. Tony Diagne
6. Aaron Hayden
7. James Kaloczi
8. Matt Saunders
9. Lewis Taaffe
10. James Potton
11. Arnaud Mendy
12. Sam Corcoran (On for David King 86’)
14. Kieran Bishop (On for James Potton 69’)
15. Jonathan McNamara
16. Mitchel Weiss
17. Ed Asafu-Adjaye
Chelmsford City: Shaun Jeffers 63’, (p)67’, Own Goal 77’, Shamir Mullings 78’
Hemel Hempstead Town: Matt Saunders 3’, 21’, James Potton 50’, Jordan Parkes (p)90+1’
Chelmsford City: Josh Rees (Foul - 29’), Shamir Mullings (Foul - 37’), Bagasan Graham (Time wasting - 90’)
Hemel Hempstead Town: Kyle Connolly (Dissent - 65'), Jordan Parkes (Foul – 88’)
Chelmsford City: Chris Bush (Second Yellow Card - 79’)
Hemel Hempstead Town: None
Referee: Elliot Kaye
Assistant Referees: Ashley List & Tom Nicholls
City Man of the Match: Shaun Jeffers