Thanks for getting back to me Kal. I thought that the 1 gal per minute rate was for during whirlpooling only. I think that I read on a paper that was included with the packaging.
It's any flow through the Hop Stopper. The Hop Stopper can't know if you're returning the wort to the kettle for another pass, or dumping into a fermenter. I'll make sure the manufacturer makes this clear.
Link Posted: Thu Aug 08, 2019 6:49 pm Post subject:
Dennis Collins here from Innovative Homebrew Solutions, manufacturer of the Hop Stopper 2.0 line of products. I hope everyone is enjoying the completely redesigned Hop Stopper 2.0. I put a lot of thought and effort into the design but there has been a good amount of discussion on the issue of recirculation/whirlpooling. I thought it might be a good idea to clear some things up.
High flow rates do pose a problem for the Hop Stopper. High flow rates pull all of the debris to the screen and compact it onto the surface. Lower flow rates, while still drawing debris to the screen still allow flow through the debris and into the screen cavity. The higher the flow, the more compaction takes place and the more flow is restricted. The other issue is negative pressure. With a pump, it is possible to flow wort through the screen much faster than the wort can flow naturally. This can cause a negative pressure inside the screen cavity. If the flow rate on the pump is high enough, the negative pressure can actually collapse the screen. For any system, the recommendation on flow rate through the screen is 1 GPM or less. When draining by gravity, this should not be a problems since a typical gravity flow rate is much less than this. However, when using a pump, it is very easy to exceed 1 gallons per minute (GPM). For this reason, any time you use a pump, meter the flow to achieve 1 GPM or less. Keep in mind that 1 GPM is a fast flow rate, faster than most brewers would use when draining so keeping your flow rate below 1 GPM will not affect your chill time. For example, at 1 GPM a 10 gallon batch would be drained from the kettle in 10 minutes.
In general, I discourage recirculation in all forms. There are basically 3 reasons to recirculate and I'll address them one at a time.
1) Recirculation to Sanitize.
This is a pretty popular practice. I personally don't do this and rely on chemical sanitizers for all my downstream equipment. I would recommend chemical sanitizers instead of hot wort recirculation for a couple of reasons. First, I think it's easier since you don't have to rig lines and do the actual pumping step. Second, I think chemical sanitizers are more reliable. However, I realize that there are other considerations and for brewers who like to do this process, I won't fuss too much about it.
My recommendation if you decide to use recirculation for sanitizing is to go very slow. You are only concerned about heat and flow does not really play into it. As long as the equipment gets hot and stays hot for the prescribed period of time, that is all the matters. Keeping the flow rate very slow assures that we avoid the issues of compaction and negative pressure.
2) Recirculation for Whirlpooling and Hop Stands.
This process does two things but does them both simultaneously so I'll lump them together but address them separately.
Whirpooling in general is something big breweries do and we as homebrewers have copied them when we really don't have to. We have the benefit of our small batches to take advantage of some things that the big boys just can't do. Whirlpooling is used to collect hops and trub in a pile in the center of the kettle so we can siphon clear wort from the sides. That's what the big breweries do. However, since we are using the Hop Stopper, we don't need to do this at all. The screen takes care of the debris so worrying about forming a trub pile is moot. Let the screen do the work. Turn off the burner and drain away.
Hop Stands are built into some modern recipes like NEIPA where you have massive late addition hops. A whirlpool is often used in conjunction with late addition hops. In the experience at Innovative Homebrew Solutions and The Electric Brewery, hop extraction is a function of contact time with hot wort rather than wort movement. The hops are already allowed to float freely in the boil and the natural convection currents after the boil is over. The addition of the whirlpool does not help hop oil extraction on a homebrew scale. In addition, any perceived increase in hop character due to wort movement is actually achieved when the hot wort flows through the hops that collect on the screen surface during the draining step - much like an old fashioned hop back. My recommendation is to rely on a hop steep rather than a whirlpool.
3) Recirculation for Chilling.
This is a very popular practice as well. There are a two scenarios and I'll address them separately.
For immersion chilling, recirculation provides wort movement which definitely speeds the chilling process. It is the movement of wort relative to the chiller that accomplishes this effect. You can do the same thing by gently moving the chiller itself. Modern immersion chillers have become very efficient (but not as efficient as in-line chillers, sorry) and it takes a very short time moving the chiller to chill the wort. However, you do generate cold break in the kettle when you use an immersion chiller. Cold break forms a film on the Hop Stopper screen that can impede wort flow and recirculation only compounds the problem.
For in-line chillers, the recirculation allows chilling with higher ground water temperatures first, then the final chill can be done with a pre-chiller on the high temperature ground water. Since we are homebrewers, we aren't chilling that much wort. A well designed in-line chiller should be able to chill within 5 degrees of your chill water with a flow rate of 2-3 minutes per gallon. A pre-chiller only has to bring your ground water to 60 F or so. My recommendation is to make a single pass with the help of some ice on the pre-chiller. This will save time and effort. In the late fall, winter, and early spring in most of the country, the ground water temps are in a range to allow chilling without a pre-chiller. _________________ Innovative Homebrew Solutions
Home of the Hop Stopper 2.0!
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