willib;
Read and re-read this.
From a distiller's point of view.
First I distill Alky so heating levels are just a little bit lower but the idea is still <- No pun intended:-) the same.
In order for you to actually distill water and make it safe to drink, you'll need to get the water up to 212F this of course is around the boiling point.
At this point water begins turning to vapor, this vapor is what you want to capture and it's mostly pure. Would be better to go the route of a refulx type , but a simple is still good.
With the way you're wanting to do by using attic heat, cold be good to pre-heat the water. Means bringing water up from whatever temp you can heat transfer from the heated air and attic to 212F, may not be necessary though.
Another way , and with your building abilities probaly easier too. Make a solar heater using high-temp glass and copper tubing. Using a temp gauge, run the water in the bottom and let the water get hot enough to come out of the top either as steam of VERY hot water, this will go along way to getting the water distilled.
This way is done all over the world and if I could keep the temp down to a better control for Alky I would be doing it too.
So far, my crude attempts have always been way too high and I ended up with more water in the first run than my normal way of using solar assisited imerssion fish tank heater.
Come to think of it this may be another way for you to try.
Since you have that cool supper Cap 12V thingy , you could run a small 150watt inverter with a fish tank heater plugged into it ( the Wally world kind that cost ~$26.00) turn it up to 100C or as close as possible. let it get to the point of making water vapor and capture that using clear tubing make a dip in the middle of the tubing so no air backup into the line and let the water vapor condense into another water container. Once your super Caps begin to get low, start charging them back up. And continue.:-)
I currently use the HF panels to charge a pretty large bank of Sub-C battery packs the are connected to a small inverter to run my imerssion heater for just this type of making my first run of Alky, however my settings are much lower (48C) and is much easier to obtain that on a 20L run.
Hope this helps
Question, what type of softner are they using ?
Bruce S