Munster failed to progress from their pool for only the second time in 17 seasons last year and they appeared determined to ensure that they avoided a repeat of that disappointment this year, as it took them just four minutes to open the scoring through BJ Botha.
The South African prop could have doubled his and his side's tally just minutes later when he crashed over again only to see his try ruled out after the referee consulted with TMO, and against the run of play the lead was wiped out after a quarter of an hour.
Ian Keatley kicked the hosts back into a narrow lead as both sides struggled to settle in the rain after the frantic opening and things remained evenly poised as the half-time whistle blew.
However, Munster seized the initiative in the second period and after Keatley added another penalty, captain CJ Stander bulldozed his way over to end a patient attack after another confirmation from TMO.
The Irish side finally found some breathing space with 12 minutes to go when they controlled the lineout after Keatley's kick to the corner, and Duncan Casey bundled over at the back of the driving maul to extend the advantage.
The hosts went searching for the fourth try which would hand them a valuable bonus point in their first pool match, and they were rewarded when Simon Zebo found space to crash over the line in the 75th minute, while Keatley added the conversion to secure the comfortable win.