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When required GPM Is Too Slow for Rec. Flow Rate @pipe size
As HO, hydraulics seems to be one of the most perplexing aspects of HVAC. Our Turbomax--used only as indirect--stipulates 5 gpm for the dedicated circulator with our Peerless MI-03 50K net output boiler. Got about 18ft of 1.25" steel pipe plus elbows etc. Head is negligible. I recall that generally 2fps is a minimum for flow speed to keep air entrained in system. According to a table I have 5gpm in 1.25" pipe will run at 1.31fps. Our VR1816 circ is set to fixed speed mode, first notch up--which is equivalent to taco 006. No real complaints with hot water, but the system psi is running 5psi above the 15 setting and just want to see if a)slow flow speed might be causing higher pressure via released air and b) we are operating at best efficiency. Those pump curves are purely about gpm and head, I guess it's up to the installer to figure out pipe size/fps. If our speed setting is equiv to 006, then at 4ft head we get 5gpm.