I have a Counter Flow like this!

[Damien M]

Below is a briefish description of what I used and how I assembled my Counter Flow Chiller. Some plumbing skills are taken for granted but feel free to ask any and all questions you have.


Counter Flow Chiller.

Materials:
1.   Inner pipe : ½" copper Tube. It comes in 25 meter lengths coated in white plastic and coiled in approx.1 meter dia coils. Bought between 2 will reduce the cost
2.   Outer hose. 1" high temp hose bought by the meter. Not cheap but temperature capable!
3.   2, 1inch to 1/2 inch T brass fitting with BSP threaded 90 tee. PTFE to Hose connection
4.   ½" Tee for gauge and Wort out.
5.   Fitting to convert form ½" compression to quick connect for Wort in.
6.   Temperature gauge, somewhat optional but very helpful for correctly modulating both Wort and Cooling water flows. Valves are not shown as they will be part of your Pump set and the discharge of the Boil Kettle
7.   4 jubilee clips to compress flex hose on to brass fittings.
8.   2 threaded sockets to fit wort discharge end ½" tee.
9.   1 ½" to threaded socket fitting for Wort In end.

I bought most of the parts from Ted Johnsons in Naas but any good Plumbing suppliers should have all that is needed. All told it cost approx 120 euros so it is not the cheap option



Method:
1.   The 1/2 " copper comes in either 4 meter straight lengths or a 25 meter coil. So this means either make a 4 meter Counter Flow chiller (not big enough) or buy 25 meters and  share between 2 people. The 25 meter will need to be unwound as it will not corkscrew into the red flex hose for the entire 10 meters I tried too and I could only get 75% in before friction would not allow further progress. Leave the plastic coating on while being unwound and take your time unwinding so as not to cause kinks in the copper. Edit: Copper Work hardens so try and minimize the unbending and bending you do.
2.   Once the copper is unwound, remove the plastic coating and wrap copper cable (5-7 mm, with insulation) around the length of the 10 meters of copper in a tightsh wrap approx. 100 mm pitch. Secure at each end with heat shrink/small cable ties/solder or whatever will not increase the overall diameter of the inner pipe. The 5-7 mm increases the inner diameter to fit in the approx 1" inner diameter of the flex hose. The spiral wrap may or may not be necessary as the centrifugal forces probably cause sufficient mixing/turbulence of the cooling water, sobject to your own choice.
3.   Once spiral is secured add sufficient washing up liquid to flex hose to lubricate flex hose and feed copper into straight flex hose until you have fully inserted and have approx. 300 mm protruding each end. Ensure spiral copper finishes inside flex hose.
4.   The ½ copper and Flex can be progressively and slowly and carefully wrapped around a Calor Gas bottle or similar to get the diameter you want, be careful as the tighter you go the higher risk of kinks. Not shown in the picture but I used the other strand of the copper cable to hold the counter flow chiller together at 4 points using a cross over wrap.
5.   Flex hose and or Copper can then be cut to suit but ensure that ½" copper protrudes sufficiently (300 mm) to allow compression joint to seal to ½" copper and flex hose seal using jubilee clips.
6.   The cooling water will be connected to the 90 of the Tee and will depend on the fittings you use. Garden hose fittings in my case. Remember to rinse out the washing up liquid prior to use. 
7.   The Temperature probe and quick connect can be connected to sockets on the discharge end. The positioning will depend on the length of your temperature probe to ensure that it is in the Wort Flow.
Operation:
1.   Prior to each use during the mash or Boil I make up an Oxi wash and circulate through the inner core for 20 -30 minutes, rinsed and then starsaned for about the same time using the hoses that will be connected to the Boil Kettle.
2.   When ready to use connect the hoses to the Boil Kettle and circulate, remembering to connect and open the cooling water first, in the opposite direction (Counter Flow) to the Wort flow.
3.   Once complete I wash with Oxi and rinse with starsan (probably unnecessary) but always make sure to drain/Blow out water from inner core. Thorough cleaning prior to use ensures the post cleaning step is somewhat unnecessary as a very minimum rinse with water. 
4.     The Temperature probe is a dead leg so should be unscrewed to confirm no Hops trapped in dead leg section


Feel free to clarify or ask questions

Damien