I'm really interested in installing a steam system to heat my mash and keep the sparge tank warm (both are plastic coolers). I think this will be my next project after I finish the fridge & fermentation cooler box thingy that's going in under the stairs (to keep my kegs cool and out of the way - I'll have to post about this in another thread if I ever get it done and it actually works). Anyhow, here's what I've found on steam:
Here are two sites about steam and homebrewing:
this one was posted above, by Wild:
http://brewery.org/brewery/library/SteInjCS1295.html
and this one is also good:
http://www.brewingtechniques.com/library/backissues/issue2.4/jones.html
Here's an interesting site that's aimed primarily at industrial use of steam and steam heater systems (I assume they're used to heat large buildings but since I live in FL I really don't know much about how the north stays warm in the winter). It's focused on the "water hammer" phenomena that has some of you concerned..
http://www.bellgossett.com/Press/good.htm
Here's my attempt at a summary:
1. You can superheat the steam by running it through a coil placed in a fire (i.e. the propane burner under the kettle or sparge tank). I think this is getting fancier than necessary but hey, if you want to go all out then I'd like to see how it works.
2. Water hammer occurs when the steam condenses on it's way into the mash tun, sparge tank, or wherever it exits. The steam will carry the condensed water along with it as it moves rapidly through the pipe and will ram the water "slug" into any elbows, turns, or restrictions in the flow line. It can be very destructive. Obviously, the way to deal with this (if you think it'll even be an issue) is to place a drain on the pipe before it goes up hill and before it reaches any bends or restrictions. Leave the drain valve (i.e. ball valve) open a touch or maybe open it slightly when or if you experience water hammer. Remember not to have a long section of horizontal or down hill pipe after the drain valve as this provides another spot for the steam to condense and form another water slug. The drain should be located down hill of the flow of steam so that the condensate will naturally flow out by way of gravity. An even easier solution, the way I see it at least, is to avoid any horizontal sections of pipe.. keep it as vertical as possible at all times so that any condensate can just flow back into the pressure cooker. For this reason I think the cooker should be below the mash or sparge tank
but remember, some section of the steam pipe must be above the mash/sparge or the liquid from the cooler will flow down into the pressure cooker. Basically, the line needs to go up the side of the cooler and then take a quick and short (to avoid hammer) downward turn into the mash where it vents.
3. Larger diameter pipe should (I think) reduce the velocity of any given volume of steam and will consequently reduce the velocity of any water slugs. Bigger pipe is better and hard pipe seems, to me, to be sturdier than soft pipe. I think copper will work fine.
4. The exit of the steam should consist of a section of pipe (a coil if you want to get fancy) with holes drilled in it placed
under that which you want to heat.
5. Shutting off the heat to the pressure cooker will cause the steam inside to cool and condense thereby creating a vacuum. This vacuum could easily suck the contents of you mash down into the cooker and create a heck of a mess. If you shut it off then make sure you can vent it somehow so that it can suck air in (or water from the sparge tank) rather than your mash.
6. I think a good design would incorporate a y and a valve that would allow you to redirect the steam to either the mash or the HLT. It would allow you shut the steam off to the mash instantly rather than shutting off the heat to the cooker and waiting for it to cool.. plus, you wouldn't have to worry about your mash getting sucked into the cooker when you shut it off, it'd suck the sparge water in instead and would be an easy way to refill the thing if it got empty (no need to wait for it to get cool enough to take the lid off).
7. Don't tamper with the safety valve. Obviously this just doesn't sound like a good idea. Drill a hole in the lid and tap it and thread a fitting on it, don't use the fitting to attach the steam pipe, the safety valve is there for a reason.
Disclaimer: I am not an engineer and haven't tried any of this myself (yet). Please don't burn yourself but if you do then please get on here and tell us about it so we can have a good laugh at your expense.
