Without any form of Heat damage on the Sentinel's weapon this mod does nothing.
The damage bonus is gradually applied as the weapon fires continuously for a certain period of time (its "overheat" duration). Once the weapon stops firing, the extra damage is then gradually removed during its "cooldown" duration, and the damage bonus is removed completely once the cooldown period expires, provided the weapon does not fire during that period of time. This makes this mod more effective on a sentinel weapon that overheats quickly and cools off slowly (see table below).
When viewing the Arsenal the stats always show the damage at full-heat.
The overheat and cooldown times for each sentinel weapon is as follows; note several weapons have no Overheat Time and so are instantly hot and do not cool-down (this may be an oversight).
Also, contrary to what you might expect, Fire Rate mods do not make weapons overheat any faster.
|Sentinel Weapon||Overheat Time (Seconds)||Cooldown Time (Seconds)|
|Burst Laser ( Prisma)||10||13|
|Deconstructor ( Prime)||Instant||None|
|Laser Rifle ( Prime)||4||20|
|Sweeper ( Prime)||10||7|