I've been thinking about a way to automate a whirlpool in my kettle for the purpose of more efficient immersion coil chilling.
Before I go on, let me just state for the record that I am not interested in counterflow and/or plate chillers. To me, there's just too much potential for clogging, and I don't like the idea of not being able to see if the inside is really clean or not. Nor am I interested in a debate over which is the best method.
Ok, so. With my immersion chiller, I have a couple choices. I can lid the kettle, turn the water on and walk away. If I'm lucky, I'll be down to pitching temp in an hour and a half. Or, I can sit there with my brew spoon stirrring, and have it done in 25 mins. Problem is, the lid has to be off to do it, and that's more cold side exposure than I'm comfortable with.
I know that Jamiel Z uses a march pump and recirculates wort in his kettle to accomplish his whirlpool chilling. Now I could do that, but I'm just a lowly extract brewer so I don't have a $130 pump, lying around.
I have seen DIY whirlpool designs that use smallish DC motors to run a paddle through the lid, so that may be doable, but I had another idea...
What if I tapped into the water pressure I'm already using through the chiller to spin an impeller shaft? Anybody here hydrodynamics savvy enough to tell me if this is stupid idea or not? Can I simply take a March pump replacement head and plumb a garden hose to it and get enough torque to spin a small paddle in the wort at low rpms? I'm on city water so I have decent PSI, I'm just not sure how that power translates mechanically.
The pump heads are fairly inexpensive. If it works, I think this could be done for well under $50 all in.