Predicted heat transfer, outlet temperatures, pressure drop and connection velocity. Counterflow, single pass.
Data used. Pressure drop is scaled from each model's rated test point (ΔP ∝ specific gravity × flow²); Cv 7.2 / 11.4 / 20.5 follows from those points. Rated points correspond to the suggested heat transfer at a 30 °F hot-side ΔT (HXM200 200,000, HXM400 400,000, HXM600 600,000 BTU/h). Heat transfer is predicted with the ε-NTU method using an estimated overall U of about 800 BTU/h·ft²·°F water-to-water at rated flow, scaled with flow (exponent 0.7) and reduced for glycol; this U is derived from published selections of comparable 5"×12" class brazed plate units, not from Rhella test data, so treat results as ±15% estimates. Port ratings (60 / 80 / 80–130 GPM) follow comparable 1-1/4", 1-1/2" and 2" units. Glycol properties are typical propylene glycol values. Design limits: 290 psi, −310 °F to 437 °F. Velocity guide (8 ft/s) is a general piping guideline. Confirm final selections with Rhella.