Many box mods come with no visible vent holes. Some vapers, including reviewers, seem to be concerned about that.
In most cases, that concern is unwarranted.
Contrary to popular belief, there is no need for air circulation around the batteries. Whatever cooling the batteries need during normal use, can be achieved by simply not building the mod from styrofoam or any other insulating material.
The various metals that mods are built from conduct heat well enough. Even 3D printed plastics do the job.
(Unless you’re vaping at 1.21 jiggawatts. If you’re vaping at 1.21 jiggawats, then all bets are off, and you will probably have needed liquid nitrogen cooling or something. But I digress.)
Vent holes exist to prevent one particular scenario, one that is indeed dangerous:
If something goes terribly wrong with a battery, for instance it shorts out, the internal temperature of the battery may reach more than 130 °C (265 °F).
When this happens, a chemical reaction sets off in the battery. Basically you can say that the battery catches fire, and it burns hot, fast, and releases lots of gasses.
In a hermetically sealed mod, the pressure builds up until the mod explodes.
In a vented mod, the gasses escape through the vent holes. The gasses will be searing hot, they might set something or someone on fire, and they are somewhat toxic. But at least the mod isn’t going to blow up in your face.
Picture a typical mechanical tube mod, made from strong and thick metal. You screw the equally rugged battery cap in, and it seals off the battery compartment completely.
Now picture the battery going thermal. As the pressure rises, the battery cap doesn’t go anywhere, until the pressure inside the mod is insane enough to rip out the threads and shoot the cap out with the force of a very hot bullet. Or the entire mod ruptures and sends shrapnel everywhere. In either case, it’s not a good situation.
This mod obviously needs vent holes, because vent holes are the only way that the gasses can escape in a controlled manner.
Contrast this with a typical box mod. Most box mods have a door that is held in place by a dinky little magnet which offer very little resistance. You can pluck the door off with your fingers.
A venting battery can easily blow it open without any additional drama. For all intents and purposes, the battery door is one humongous vent hole.
Of course there may be some box mods that have a tightly sealable battery compartment. If the battery door doesn’t come off under a moderate pressure, then the mod needs to have vent holes instead.
Being concerned about safety is a good thing. But when users worry, and reviewers carry on, about the lack of visible vent holes in box mods with big battery doors that can be opened with very little force, their concern is misplaced in my opinion.
Please take the time to think about why vent holes are a good thing. Also, when they are necessary, and when they aren’t. If you keep these things in mind, you might be able to catch less obvious things.
Like good or bad placement and sizing of any vent holes. Whether a battery door closing mechanism is well engineered or not, from a safety perspective. If a box mod that looks like swiss cheese needs to look that way, or if it’s just a bad (or good?) styling decision.
If you’re a reviewer, I promise your reviews will be better for it. If you’re not, I hope you found this interesting anyway.