Hydronics and pump calculators
Water-side calculations for boilers, chillers and hydronic heating: heat carried by a flow, pump power and pipe velocity.
GPM to BTU Calculator (Hydronic Heat Transfer)
Convert water flow and temperature difference to heat (BTU/h and tons), or find the flow a load needs, with the hydronic 500 × GPM × ΔT equation.
Answers: How many BTU/h does my water flow carry, or what GPM do I need?
Pump Horsepower and Power Calculator
Calculate a pump’s water horsepower, brake horsepower and electrical input from flow, head and efficiencies — and its yearly energy cost.
Answers: How much power does my pump use?
Pipe Flow Velocity Calculator
Find water velocity in a pipe from flow and inside diameter, or the flow at a target velocity.
Answers: How fast is water moving in my pipe?
Pipe Pressure Drop Calculator (Water)
Friction head loss and pressure drop for water flowing in a pipe, with the Darcy–Weisbach equation, the Swamee–Jain friction factor and water properties at the actual temperature.
Answers: How much pressure (head) does my pipe lose at this flow?
Water-side basics
Hydronic systems move heat with water (or a glycol mixture). Three quantities tie everything together: the flow in gallons per minute, the temperature difference between supply and return, and the heat carried, 500 × GPM × ΔT for water. Pump power follows from flow and head, and pipe velocity from flow and the actual inside diameter. Fluid properties, pipe dimensions and velocity limits come from the manufacturers of your fluid, pipe and pump — no tables are reproduced here.