HERMS Questions

So I've been trying to build myself a HERMS setup for some time, with partial success, and want to put some questions to the group:

1) Originally, I only had 25 feet of 3/8 copper tubing for my heat exchange coil.  Worked for keeping things at a certain temperature, but I just couldn't get it to work for raising the temperature in any reasonable amount of time.  I tried, as an experiment, hooking up my pump (which I found out is one of the 1/50HP March pumps, not the 1/25HP) to the 50 feet of 3/8 I use for cooling, and I only got 1/2GPM.  Slow.  In peoples experience, is this rate too slow for use in  HERMS setup?  I'd really rather not have to buy any more copper if I don't have to.

2) If I do buy more copper, when people mention the 1/2 copper tubing, are they talking Type L (1/2 ID) or Refridgeration Type (1/2 OD, 3/8 ID).  And would I need to get 50, or could I get by with 30 if it had much more surface area?

Why copper?  Especially  why soft copper?

Pumps: Look at the LG 3MD HC  Much more robust, three times the flow, yadda yadda yadda.  In the LG pump head: ya gotta take the center ceramic shaft out and replace it with a teflon one ( it's 1/4" dia)  and clean the black moly lube out of the center bore.  Why'd they use a ceramic shaft and lube it with black moly? Because it's rated for HC (high corrosion) and Ceramic  is a sure thing.  But that meant it  absolutely needed a lube.
But after that you are golden

Here's an interesting take on HERMS
http://sdcollins.home.mindspring.com/HERMS.html

Which, if you think about is sort of,  kind of,  in an idiosyncratic  way  spot on given certain parameters.
1.) Your beer has it's personality cast in the first fifteen minutes of mashing irrespective of the temperature you get to later on.  That's just a function of mashing.
2.) Most HERMS and RIMS set ups are slow.  look at yours.  You are probably pushing wort through the copper tubing which is immersed in a tank of hot water.  It's slow. 
So he needs a slow march pump, a weak heater, and a slow exchanger.  That way his conclusions are spot on. 

You can get past much of this gobbldy gook by (1) using a more direct heat like an electric heater in the  RIMS recirculation tank, using a larger tank for heating the mash tun wort - say a 5 gallon tank with the heater in it which will bring the wort up to a temp faster and then let you infuse the mash with all that already hot-to-spec-fluid and  of course  a bigger pump to move it all around faster.

If you are absolutely dead set on doing it the way you are, consider getting rid of the Copper tubing and get yourself some SST thinwall half inch tubing.  The thermal transfer rate between Copper and thinwall  SST is not enough to matter. The diameter of the tubing will facilitate greater heat exchange and faster through-put. Larger diameter  = more surface area and more laminar flow.  Also think of a larger fluid volume around your heat exchanger. The larger volume will have greater thermal inertia which equals more heating power.

As an aside, an old school plastic injection molder's trick for extracting more heat from the molds thus increasing the speed  of cycles  is to turn down  (close it up a little) the OUT-PUT valve on the injection mold's water cooling manifold.  This caused two things to happen: (1) the water took a little longer to get out, and (2) water being a phase change material accepts heat input differently at different temperatures.  They old school molders found that if the water got a little warmer it'd draw off more heat faster from the mold.
So turning the valve on the out put end down a little  - though counter intuitive - works to cool the molds faster.

The same principles can work for heating any fluid with water as it's base.


I was going to go HERMS and ended up abandoning it entirely for a modified RIMS/Brutus approach.

We simply used a counter flow wort chiller to accomplish this. The chiller was hooked up to the hot liquor tank with 185 degree water running through. The wort was then pumped counter flow and back into the mash. of course this requires 2 pumps and a "spare" counterflow chiller. All valves wide open on both sides to prevent any unneeded exposure to the high heat. Wasn't supper fast but would raise the heat from 150 -168 for mash out in about 20 minutes for 18 gallon batches.