Re: Why do soda cans explode in a controlled environment?

Sounds like a dangerous situation and I would highly recommend moving your Coke storage elsewhere as soon as possible to avoid injury (not to mention the annoying clean-up afterwards). Here is what I think is happening:

First, your boiler is not always on - it cycles as needed, according to the temperature in the rest of the house. When it is on, the temperature of the air immediately surrounding the boiler increases quite rapidly and can become quite high. As the temperature increases inside the cans, the pressure also increases because the CO2 gas inside is expanding. Soda cans are only designed to withstand a certain amount of internal pressure (depending on their thickness and overall design) and it sounds like you are really pushing those limits.

Second, the cola is exploding and the seltzer isn't because the Coke has a higher carbonation level. Therefore, more pressure is created inside those cans.

Lastly, repeated heating and cooling can't be good for the cans or the soda either. Think of it as a freeze/thaw effect - odds are that the longer they stay near the boiler, the more failures (explosions) you will experience. Your soda won't taste all that good either. Heat accelerates the oxidation of the cola flavor and it will probably taste a little strange as it gets closer to the end of its shelf-life.

If you'd like to try a quick experiment, blow up a balloon with air (not too full) and leave it in the same spot as your Coke cans are right now. About 10 minutes after you hear the boiler kick on, go take a look at the balloon again. The difference in size will give you an idea of the pressure change happening in those cans - only they can't expand like the balloon...

But first, I'd move those cans to a cooler part of your basement. ;)

Kieran