I take a keggle HLT full of cold water and light a burner under it. Previous to lighting, the keggle is bone dry underneath (the bowl that is over the flame, and the whole exterior). There are no leaks.

Minutes after lighting, I'll hear the sizzle and pop of water dripping onto a hot surface.

I look under hlt and see water dripping off of bottom of bowl shape onto burner and insta-vaporating.

This drove me NUTS the first few times I have run my system (it's really new). I was convinced I had a leak somewhere.

Anyway, doing my brewing science courses and listening to podcasts about propane I had a realization. I think that propane, with it's simple carbon and hydrogen make-up, when going through the oxidation reaction (burning), is putting off H2O vapor, which is condensing on the cold metal of the keggle bottom (cold water inside).

It's weird to think about flame making water, but I can't think of any other explanation. When I pump hot wort into a vessel and light it's burner, it doesn't happen because the wort is already over about 150F, maybe too hot for the vapor to condense on.

Perhaps you should RDWHAHB. In the BN Army we stress a firm "no pants brewing" rule! There are much more important things to stress about.

And you answered your own question. Combustion creates (in addition to all those greenhouse gases that are causing global warming - right, JP?) water vapor. Since the HLT has cold water in it, the vapor condenses on it.

It's also why your car pumps out all that "visible steam" in the winter time. That is, until the exhaust temp warms up and prevents the immediate condensation.


Mylo

yes, if you think back to your chemistry course, the by product of any combustion is H2O and some sort of carbon and oxygen mix (CO and CO2). but this amount of water would not condense over a certain temp. My bet is that at lower temps you have a large temp differential between the air and the kettle. this can cause condensation from the ambient air.

yeah, I wasn't great at chemistry in the past. Theoretical math was okay, but not chemistry.

I've been studying brewing chemistry as part of my ABG program and it makes a bit more sense to my older brain than it did to my 20-something year old brain.

I'm more relaxed in my garage brewing than anywhere else. I just get obsessed with little things and cannot get them out of my head until I understand them. It's probably a sign of mental illness, but it makes me good at my job and other detail-oriented things. I'd hang with the no-pants, but I'd rather not muck-up any of my kilts. Also... below freezing in garage some days. YIKES! On those hot carolina summer days I have seriously considerred it. 105F in the garage is brutal.