Cauldron of Brewing - Heat and time

[JulesLetters]

I have been looking for ways to heat water to give to a large population. Many ideas, both absurd and practical have come about. One of the most curious I found was the Cauldron of Brewing. It has similar statistics to a cauldron, suggesting it holds 1 gallon of liquid.

The text states it is capable of heating any liquid placed inside anywhere from room temperature to hot enough to boil salt water.

How long does this take? Is it fast enough that any liquid entering the cauldron is heated? Does the change take place over a round?

I realize I'm poking at what might be an opinion question, but the item set me to thinking for quite a time, so I thought I would ask.

[Bob Bob Bob]

You're overthinking this. "Wall of fire can be made permanent with a permanency spell. A permanent wall of fire that is extinguished by cold damage becomes inactive for 10 minutes, then reforms at normal strength." Permanent wall of fire, infinite heating.

[JulesLetters]

I'm playing with only Society-legal material at the moment, so Permanency is not on the table as an option, sadly.

I attempted to skip right to the punch:
http://paizo.com/pathfinderRPG/prd/advanced/spells/geyser.html
Unfortunately I don't have any willing candidates for standing around holding concentration on a spell forever!

One of my more interesting and more math-heavy experiments was using a Stone Horse to generate energy to convert to heat. Punchline: 225 kW, which is enough to heat about 2 gallons a round from 65F to 140F. Work can be shown on request! I don't think the concept for cavitation heaters exist in the world I'm in, so I would have to Wish for something to convert rotational energy to heat, or do the conversion via friction with something like a giant bow drill.

(Reading what I wrote above, I think 'overthinking this' is a correct analysis.)

All that said, I am still interested on what interpretations there are for the Cauldron of Brewing, as the threads I saw for it all focused on its skill bonus rather than its other peculiar ability, which appears quite useful but is vaguely defined.

[Bob Bob Bob]

Honestly, it doesn't say it does it instantly. It only says it does it. With no given time I'd assume it heats liquids at the same rate as, say, putting it on a bonfire. From a rules point of view though? The answer is "ask your GM" or "@#$% if I know". It's not defined and there's really no good answer I can give that I haven't already.