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FlyGuy · 03-29-2007, 07:44 PM

Recent discussions of step mashing and decoctions got me thinking about ways to use my 10 gal Rubbermaid MLT (see myconstruction here) for multi-step mashes. A typical way to multi-step would be to heat the mash with a burner, but clearly that isn’t possible with a plastic cooler (one big drawback). Other options include raising the temperature of the mash using decoctions or additional infusions of boiling water, neither of which appealed to me.

So I thought I would try to design a steam infusion system based on the success of brewman !’s SIMS (thread 1, thread 2) and the info in this other article. Brewman! was kind enough to help me with design and testing of the system (thanks brewman!). Overall, this was an easy system to build, and I had fairly good success in a water-heating trial (details below).

Here is what I built:

FlyGuy · 03-29-2007, 07:44 PM

• pressure cooker ($19.99 for a 1.5 gal/5.5L cooker, the MINIMUM size I would recommend)
• 1/4" x 1/8" tube/MIP angle valve ($3.95 – Watts A-41)
• 2' @ 3/8" copper tubing for a manifold ($2.40)
• 1/4" copper T-junction ($0.49)
• 6' @ 1/4" ID x 7/16” OD crush-resistant, high temp. silicone tubing ($10.14 – McMaster Carr # 3184K1)
• hose clamp ($0.99; optional)

Total cost: $37.96 Canadian, or about $30 USD

FlyGuy · 03-29-2007, 07:45 PM

[Disclaimer: Although this worked for me, I do not recommend tampering or modifying a pressure cooker in any way. Modifying or removing safety devices on a pressure cooker can lead to explosion and possible injury. Blah, blah, blah...]

Pressure cooker: Pretty much any decent size pressure cooker (use AT LEAST a 1.5 gal unit) will work, although I wish I had gone with a much bigger unit (see below). If you are lucky, you might be able to unscrew one of the fittings on your pot, insert a tee junction, and run attach your valve to the pot this way (worked for brewman !; see here). The fittings on my pot were too small, so I tapped a 1/8” NPT thread into the lid, and screwed in my valve to control the flow of steam. Works perfectly. I also added a 3 inch piece of 1/4" copper tubing to the valve (it has a built in 1/4" compression fitting) to attach the tubing. A 3/8" inch hose clamp would be a good idea – mine held without it…. until I kinked the silicone tubing and it blew the hose right off the pot!

Steam manifold: I bent 3/8" tubing around a small pot to form a loop. I sweated a T junction to complete the loop. I then drilled about eight 1/16" holes in the tubing with a drill to allow the steam to escape. The silicone tubing can be stretched over the end of the T junction, and mine was snug enough that it did not require a hose clamp. A small thumb clamp can be added to the hose if you want to stop the flow of steam at the manifold end (useful to prevent backflow when the steam flow is stopped at the pot).

FlyGuy · 03-29-2007, 07:45 PM

To test the system, I heated 5 gallons of water from 122 degrees F to 152 F. Using only steam for heat, I was able to raise the temperature of the water in the cooler in about 15 minutes. I was a bit disappointed, since Brewman was able to heat water with his system at about twice that speed.

I did some trial and error with finer hose (1/8" silicone tubing), and a manifold made from smaller 1/4" copper tubing (see below). While the smaller diameter tubing and manifold increased the pressure of the steam injection, it did little to change the heating times (in fact it took longer).

I discussed this with Brewman across multiple, multiple PMs

and we decided that the bottleneck in my system was the heat source. Through some fancy calculations based on heat transfer in the cooler, Brewman calculated that I was delivering the equivalent of 2.4 kw of energy with this system, which is approximately the output of the burner on my stove. We also decided that a larger pot, which holds a greater volume of water, would be able to deliver more heat to the manifold because it has a greater capacity to store energy in the form of heat and pressure. I confirmed this with my system – I had an initial rise in temperature that was very fast for the first few minutes of steam injection, and then the heating dropped to a lower but consistent rate (apparently as the pressure in my pot dropped and the stored energy was transferred). Brewman’s system was presumably more efficient because he has a 4.5 gallon pressure cooker that can store 4 times the heat.

Bottom line: If you want faster heating, a larger pressure cooker and/or a hotter heat source (e.g., a gas burner??) is necessary. However, the heating time in my system seems reasonable for achieving a multi-step mash. I am going to try one tonight when I brew an AG hefe-weizen recipe, and I will report back with my success.

**bradsul** · 03-29-2007, 07:58 PM

This looks like an awesome project. I think I will put it on my to-do list.

Thanks for the write up!

**fifelee** · 03-29-2007, 08:06 PM

Nice. I will do this. Oh yes I will. It shall be done. Thanks for doing all the hardwork.

**kladue** · 03-29-2007, 08:29 PM

For those folks doing recirculating systems inject the steam into the wort and give up the stirring and get the same step times.

**Yuri_Rage** · 03-29-2007, 08:33 PM

Quote:

Originally Posted by kladue

For those folks doing recirculating systems inject the steam into the wort and give up the stirring and get the same step times.

That's exactly why I'm going to start steam mashing. Steam through a well built manifold should agitate the wort enough to avoid stirring. The parts are starting to arrive for a corny-sized steam vessel (see brewman's thread). My next brew will be steam powered!

**bradsul** · 03-29-2007, 08:38 PM

I was quite happy with my 52L cooler and shiny copper manifold but now it's just not good enough. I want to step mash now.

brewman ! · 03-29-2007, 08:44 PM

Good writeup, Flyguy !

Quote:

Brewman’s system was presumably more efficient because he has a 4.5 gallon pressure cooker that can store 4 times the heat.

My system isn't more efficient, my system just stores more heat until you open the valve.

Saturated water at 15PSI is 240F. When you open the valve the pressure drops and the water flashes to steam, down to 212F. The more liquid water you have at 240F, the more steam energy you have stored. In fact, a 20Q pressure canner at 240F has enough energy stored to raise a typical 5 gallon mash 30F all by itself. How fast that happens depends on how far you open the valve and how much bubbling, etc you want in your mash.

As I've mentioned before, due to viscosity reasons, mash heats easier than water. The steam bubbles in water tend to be big and they take a long time to collapse. The heat gets released when the bubbles collapse. Thus a mash tends to heat better with steam than does water. So Flyguy, heating your mash may work better than heating plain water.

I found I really had to keep the steam flow rate down when heating with water. If I turned it up too much, the bubbles wouldn't break until the surface and the steam energy was released to the headspace above the water. I haven't had any problem like that with steam heating the mash. I'll be very interested to hear how you make out heating your mash tonight !

Flyguy: were the holes in your manifold really 11/32 ? (Larger than 1/4" ?) Or might have they been say 11/64 ? Did steam come out of all the holes or just one ?

Aside: I calculated 2.4KW based on heating 5 gallons 30 degrees F in 10 minutes.

I can't wait to hear how your mash goes tonight. Don't forget to stir !