Supporters mingled with players, some of whom were dripping wet after being soaked by fans in the stocks, including all the new summer arrivals - and had the first opportunity to buy the new black away kit.
Manager Brian Laws, assistant Russ Wilcox, chairman Steve Wharton and new signing Tommy Johnson all took part in a question and answer session with fans.
And Wharton played alongside club staff and supporters club members in a eight-a-side friendly game against the Iron Filings, United's official supporters side, which was refereed by the Scunny Bunny.
Elliott, who also braved the blistering heat to play in the match, told Iron-Bru.net: "It is fantastic to see so many people here on such a hot day, especially fans in the new kits.
"The players all look in great shape, and it's a great way to kick off the new season."
Supporters club chairman Andy Brown added: "I'd like to thank everyone at the club for helping us put on the day - especially Steve Wharton, Simon Elliott, Jason Oxenforth and Jamie Hammond for agreeing to play against the Filings.
"How many club chairman would be willing to play football with the fans? It shows that when it comes to football we're all on the same level.
"It's our first attempt at an open day, we have learned a lot from it and hope next year's will be bigger and better."