Build up total dynamic head from piping, fittings, coils, valves, and elevation.
| Component | Typical Range | Your Value (ft) |
|---|---|---|
| Cooling coil / heating coil | 5–25 ft | |
| Control valve (2-way) | 5–20 ft | |
| Chiller / boiler | 10–35 ft | |
| Strainer (clean) | 2–5 ft | |
| Heat exchanger / HX | 5–15 ft | |
| Static elevation (ft) | 0–50 ft | |
| Other / misc | — |
| System Type | Typical TDH | Notes |
|---|---|---|
| Small residential / fan coil | 20–35 ft | Short runs, few fittings |
| Medium commercial CHW/HHW | 40–80 ft | Multi-floor, 2-way valves |
| Large building primary loop | 60–120 ft | Long mains, chiller + coils |
| Condenser water (cooling tower) | 50–80 ft | Tower static head + pipe |
| District energy distribution | 80–200 ft | Long runs, multiple buildings |
Doing this for a whole building? See this step inside a connected AIM Works project — loads, ventilation, equipment, and Design Review in one place.
Book a Demo →This pump head estimator builds up the total dynamic head (TDH) a hydronic pump must deliver. It computes pipe friction from your flow, Sch 40 pipe size, equivalent length, fluid and temperature, and a fittings multiplier, then adds the water-side head loss of coils, control valves, chillers, strainers, heat exchangers, and any open static elevation. The result is TDH in feet plus an estimated pump brake horsepower.
Use it to size a pump or sanity-check a selection before pulling published curves. Pipe friction is computed with the Darcy–Weisbach equation and the Colebrook–White friction factor; equipment losses come from manufacturer cut sheets entered as feet of head.
| Velocity | V (ft/s) = Q (GPM) ÷ 449 ÷ A A = π · d² ÷ 4 (ft) |
| Pipe friction | hL = f · (L ÷ D) · V² ÷ (2 · g) × mfittings |
| TDH | TDH = hL,pipe + Σ hequip + static lift |
| Brake HP | BHP = Q (GPM) × TDH (ft) × SG ÷ 3960 ÷ η |
Pipe friction uses Darcy–Weisbach with the Colebrook–White friction factor (f = 64 ÷ Re below Re 2,300; steel roughness ε ≈ 0.00015 ft), scaled by a fittings multiplier (≈1.3 typical). Fluid viscosity and density come from the same property data as the Hydronic Pipe Sizer (IAPWS water; Dow/ASHRAE glycol viscosity; MEGlobal and Melinder glycol density), evaluated at your temperature. The constant 449 converts GPM to ft³/s; g = 32.174 ft/s². Heads are in feet of the circulating fluid. The pump power constant 3960 = 33,000 ft·lb/min per HP ÷ 8.33 lb/gal, SG = ρ ÷ 62.4 corrects it for glycol, and η is the assumed pump efficiency (70% here; use the Pump Selector for your own pump and motor efficiencies). The multiplier is a rule of thumb; a detailed design totals fitting equivalent lengths. Basis: ASHRAE Fundamentals and Cameron Hydraulic Data.
AIM Works brings peak loads, ASHRAE 62.1 ventilation, equipment and plant sizing, compliance checks, Design Review, and engineering deliverables into one connected mechanical design workspace.
Duct and pipe distribution sizing is planned for V2 — at launch, keep using this calculator for that step.
Results are design estimates for preliminary sizing. Verify final designs against applicable codes and standards — engineering judgment and a licensed professional engineer’s review are required.