This won't be easy. I'm a hydraulic systems designer but my math skills are limited to basic algebra which would make it a challenge for someone to give me a formula to do what I'm looking for. Here goes: I want to heat water to a specific temperature by pressurizing it and forcing it through a relief valve. The problem being the flow will vary but I need the final temperature to remain constant. I can proportionally regulate the relief setting (Delta-P) as the flow changes. So, I need to know what the relief setting needs to be at particular flows to maintain a particular temperature. Any takers?