From: rcpt@rw9.urc.tue.nl (Piet Tutelaers)
Newsgroups: rec.crafts.brewing
Subject: Maischbottich design
Date: 30 Sep 92 23:27:03 GMT
Reply-To: rcpt@urc.tue.nl





	   Design considerations for making a `Maischbottich'.


When I made my beer some time ago I used a self-made maischbottich (a
german word for which I have no english equivalent, perhaps brew kettle
or something like that).  This brewing device consisted of an ordinary
plastic dustbin (30 liter) with a lid.  In the lid were made holes: one
for an electric immersion heater (marked by xxx) and two small holes for
the stirring-rods (marked by ooo) of a kitchen mixer.  The heater was
controlled by a thermostat build around the TDA1023 chip (see Philips
Technical information 25 `Design of time proportional temperature
controls using the TDA1023' from D.  de Ruiter, march 1977).  The sensor
(marked by a single *) consists of a resistor who's resistance is
temperature dependant.  See next pixture:


                ----- | ------ | -------
                 |    |        |      |
                 |    |        |      |
                 |    |        |      |
                 |    |        |      | 
                 |    |        |      |
                 |    |        |      |
                 |    |        |      |
                 |    |        |      |
                 |    |        |      |
                 |   xxx      ooo     |
                 |   xxx      ooo     |
                 |*  xxx              |
                 |   xxx              |
                 |                    |
                  --------------------

This equipment has the following disadvantages:
 a) the maische will partially burn 
    Because the heater has direct contact with the maische it will
    create burned grain parts which will cause inferior and possible
    unhealty beer. The mixer, introduced to propagate the heat througout
    the kettle, can not prevent this. The Bruheat boiler seems to have 
    the same problem. Commercial breweries avoid this problem by using 
    indirect heating with steam but that is very costly for amateurs to 
    imitate.

 b) equipment not suitable for filtering
    In order to filter the wort all goods must be transferred to a
    special sparge equipment (a grain bag made according to the drawings
    given by Dave Line in his book `The Big Book of Brewing').

Next improved equipment tries to cope with these shortcomings:


                ------------------------
                 |                    |
                 |                    |
                 |                    |
                 |                    |
                 |                    |
                 |                    |
                 |                    |
                 |*                   |
                 |- - - - - - - - - - |
                 |   xxx        xxx  ===\
                  --------------------  \


The heater is now covered by a plate (- - -) consisting of a lot of
small holes that enable sparging after mashing.  A tap (===) below this
plate controls the filtration process.  Before loading the maische the
kettle is filled with water so that the space below the plate is kept
free from grain particles to avoid burning.  The mixer can be omitted. 

Although this idea seems nice, on paper at least, I would like to get
some input on:
  i) how many holes are needed for optimal sparging
 ii) what form is needed to prevent burning? 

With a carefull design we can even save energy (by isolating the
kettle) and control the temperature during the sparging (78 degrees
Celsius) process.

Are there brewers around who can comment on above ideas?

Proost! (Dutch for `cheers')

--Piet
Newsgroups: rec.crafts.brewing