I recently had a new HVAC put in my house and had them leave me the 3/4" copper tubing going to the old outside unit. Looks like there is oil on the inside. would this Acid#5 work for that? Was thinking about making a wort chiller with this.
Are you thinking IC or CF? if IC then you don't really need to clean the inside but if you want to you can just run hot soapy water through it. or PBW. If a CF then you will need to clean it very well. I would think PBW would take care of it but if not white vinegar probably would, just rinse really well.