Dump the Pump: Newton, Pascal, Bernoulli, and Homebrewing

Gravity brewing 001.JPG

Physics is your friend, and can save you money on homebrewing equipment.  I'm no enemy of Chugger or March, but let's face it: most brewers don't need a pump if they can employ some basic brew system design advice to let physics do the work for them!  And here's the thing: principles of physics will never break down on you.  They won't burn out.  They don't (really) need to be primed.  And they're free.  So let's drink a toast to Sir Isaac Newton, Blaise Pascal, and Daniel Bernoulli and talk about how gravity, pressure, and suction can eliminate the need for pumps in your brewing (without requiring you to brew from atop an A-frame ladder).

When building out my new system, I wanted something simple (shocking, I know) and convenient.  Therefore, I wanted to build it more or less horizontally for ease of access and operation, and as a result came to the conclusion that pumping was my only real option.  But a funny thing happened on the way to the brewery: it turns out I couldn't stand the added steps, equipment, cost, and cleaning that the pump required, and went back to the drawing board.  Not for the first time in my brewing life, I thought, "well, why don't I just try the simplest thing and see if it works?"

With the minimum possible drop, could I transfer using nothing but gravity, hydrostatic pressure, and siphoning, and still work from counter height to the carboy without the need for a pump?  The answer was yes, and I now have a never ending source of transferring energy to go from my mash tun to my kettle, through my plate chiller, and out into my carboy.  Simple.

But let's talk numbers.

My mash tun sits on the countertop, a standard 36" from the floor, with a drain and ball valve roughly one inch above that.  Draining from the mash tun to the kettle, I have a ZERO inch drop from the ball valve outlet to the lip of the kettle, and a drop inside the kettle (once the beer clears the lip) of 10".  The hydrostatic pressure of the liquid in the mash tun is sufficient to get things flowing over the lip despite the lack of an actual drop, and once started, Bernoulli's Law takes over and keeps pulling liquid until the mash tun empties.  Nice and easy.

Now, once in the kettle, I boil as usual, and the time comes to chill things down.  I have a weldless fitting on my kettle, and I drain from it using the same principles as the mash tun's transfer.  Open the valve and let gravity/pressure do their job.  How big a drop?  Well, it's a whopping 4.5" from the barb to the "Wort In" side of the plate chiller...but here's the thing.  The easiest way to use my Shirron chiller (see the photo) is to lay it flat and clamp it to the counter that the kettle sits on, which means that to get OUT of the chiller, the fluid is now running UPHILL!  Before I let logic overcome reality, though, I just opened it up and observed what happened - no problem.  Once the flow gets going, we're home free again, thanks to Monsieur Pascal and Signor Bernoulli.  

Upon exiting the chiller, there is a 2.5" drop from the lip of the chiller output to the lip of the carboy, and then about a 6" drop into the carboy.  In case you're curious, it flows at a nice, healthy rate, too: 4.5 gallons of beer takes me nine minutes to drain/pull through the chiller, for a rate of about two minutes per gallon.  Even using a pump, you wouldn't want to (or be able to) go faster, chilling with cold tap water, so there's no real time loss.

And that's it: pump-free transfer.  I've literally never had a stuck lauter/sparge or transfer out/through the chiller.  Physics is some reliable stuff.

Obviously you'll need to do some tweaking to make this fit your system, but the gist is a simple one: you don't need big drops in height to make a gravity-fed system work, because gravity's not doing it all on its own.  Pressure is the real lead dog on this one, and so long as you have enough to get things moving, the rest is simple.  

Most three-tier stands on the market have about 24-30" of total drop, and most still make use of a pump to get the finished wort into the fermenter.  

My total drop, mash tun to carboy, with no pumps employed?  17 inches.

Keep it simple.