The hot liquor tank is constructed from a standard stainless steel cooking pot, At the bottom of the tank a hole is cut and a heating element screwed in, The heating element used is quite a low power one and is only 1kw. This is all that is really needed to brew on this scale and allows quite accurate heating control.
Incase you were wondering, Liquor is the term for water when used in brewing.The filling and emptying of the tank is all done through a 15mm stainless steel connection at the bottom of the tank. The method of creating this connection took a bit of trial and error but basically consists of cutting a hole in the bottom of a tank so a stainless steel coupling can be pulled through. This makes quite a tight fit but is not water tight, To make the connection water tight the coupler is soldered using silver solder to the stainless steel tank.
The level within the tank is measured by a standard fuel level gauge level transmitter, The level gauge has a float which floats on the top of the water and switches several magnetic read switches inside the level gauge. This allows the system to accurate turn on and off at particular water levels but doesn’t give a very high resolution level reading. The read switches are placed at what appears to be 10mm or so intervals within the level gauge.
As well as the level gauge transmitter I have also placed an extra simple floating level switch at the top of the tank, This is so the system can automatically stop the water supply if ever high level is reached within the tank.
As well as measuring temperature the tank has a temperature probe inside it to accurately measure the temperature of the hot liquor. The probe is made from sealed thin copper pipe with a one wire temperature device, A ds18b20 chip located within it. I also put a little heat sink compound within the tube to allow for more accurate and faster temperature readings.
Although I currently don’t have this tank insulated, I will probably try and insulate the tank shortly by some simple method. Perhaps part of a hot water cylinder jacket around it.