Hello, I have electronic equipment that produces a lot of heat and is cooled by air. I'm thinking that it would be a good idea to use this heat in my water heating system (house is heated with water batteries and underfloor water heating, by oil burner and electricity - in summer it's cheaper to use oil, in winter electricity) I can quite easily and cheaply TIG weld aluminum tubing to the aluminum heatsinks, and circulate water through them. I'm not sure what my heater is made of, but probably copper because the plumbing is copper(?) Only the portion that is welded to the heatsink is required to be aluminum, the rest of the system can be PEX for example. My questions are: 1. Will it cause problem to connect this system if my houses uses copper plumbing? (galvanic compatibility?) 2. Will connecting PEX tubing to the aluminum heatsink/tube, and then feeding into the copper heater inlet solve the issue? 3. Is making system from aluminum and PEX that will circulate water/other liquid in a closed loop with a heat exchanger that is submerged inside the house water heater the only alternative in case making an open loop is not possible? (I guess I can switch all the heatsinks and copper and braze copper pipes to them, but that's both quite expensive and labor intensive) Many thanks to the helpers! PS. I would like to add that I live in Europe and use my own well water supply, which are quite soft, thinking of adding an RO system as well, for the entire house in the future. Also I'm not required to follow any building code.