Tagging along with this one as well since my first RO had very poor performance and I was looking for ways to heat the input. I know the industrial RO unit at the local Exxon/Mobil plant uses steam to pre-heat their lines and the performance is supposedly much better the hotter it is. I was going to use a heat tape (used to keep pipes from freezing) and wire in my own thermostat but looking at my electric bill decided against it
