ebay a 30a temperature controller
http://www.ebay.co.uk/sch/i.html?_from=R40&_trksid=p2050601.m570.l1313.TR0.TRC0.H0.X30a+temperature+controller.TRS0&_nkw=30a+temperature+controller&_sacat=0
similar in size and shape to the popular stc1000 fridge controller but with only 1 x 30a relay fitted rather than 2 x 10a so will heat Or cool and will handle elements which draw more that 10a without burning out..
to box use a big enough container (��ãshop snap lock sandwich boxes are cheap n chearful
and use a suitable 15a lego brick connector
In addition to the 'lego brick', a box, and the controller, you will need
3 x grommets 1 for power in 1 for the boiler/element lead, and 1 for the sensor. 3 x lengths of 1.5mm sq flex wire (2 x brown n 1 x blue would be good)
to wire up , screw the live, neutral, and earth leads from the power input lead into a separate terminals in the lego brick.
from the live and neutral terminals use 2x lengths of wire to connect the control box power in terminals (CLEARLY MARKED POWER IN) polarity isnt an issue..
Then take the 3rd bit of wire and connect live from the lego brick to one side of the controller relay terminals.(again clearly marked on the controller.
Then connect the out leads neutral and earth wires to Neutral and earth at the terminal block and connect the live wire from the output side to the other relay terminal on the controller. - DONE..
a pid and ssr/heatsink could also be used but imho a pid is overkill
and while the temp may overshoot by a fraction of a degree with a simple on/off controller a litre jug of cold tap water is an easy adjuster if needed which i doubt..
ps remember to give the hlt a good stir to normalise the temp throughout before drawing as if left any length of time at target temp the liquor can layer out into cooler below and warmer above the probe point. resulting in a cooler than expected draw from the hlt if not stirred up.