Pump Head Estimator

📈 Pipe Friction Loss

System Flow Rate (GPM)

Pipe Size (nominal)

Equivalent Pipe Length (ft) Include fittings as equivalent lengths (or use multiplier below)

Fittings Multiplier

🔌 System Components (ft H₂O)

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	—

📊 Total Dynamic Head

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Total Dynamic Head (ft H₂O)

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Pipe Friction (ft)

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Components (ft)

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Est. Pump BHP

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Pipe Velocity (ft/s)

📚 Typical System Head Reference

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

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About This Calculator

This pump head estimator builds up the total dynamic head (TDH) a hydronic pump must deliver. It computes pipe friction from your flow, pipe size, equivalent length, 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.

Formula & Method

Velocity	V (ft/s) = Q (GPM) ÷ 449 ÷ A A = π · d² ÷ 4 (ft)
Pipe friction	h_L = f · (L ÷ D) · V² ÷ (2 · g) × m_fittings
TDH	TDH = h_L,pipe + Σ h_equip + static lift
Brake HP	BHP = Q (GPM) × TDH (ft) ÷ 3960 ÷ η

Pipe friction uses Darcy–Weisbach with the Colebrook–White friction factor (steel roughness ε ≈ 0.00015 ft, water at 60°F), scaled by a fittings multiplier (≈1.3 typical). The constant 449 converts GPM to ft³/s; g = 32.174 ft/s². The pump power constant 3960 = 33,000 ft·lb/min per HP ÷ 8.34 lb/gal, and η is the assumed pump efficiency (70% here). Basis: ASHRAE Fundamentals and Cameron Hydraulic Data.

Frequently Asked Questions

What is total dynamic head (TDH)?

Total dynamic head is the total resistance a pump must overcome at design flow, in feet of water. For a hydronic loop it is the sum of pipe friction along the critical path plus the water-side head loss of equipment such as coils, chillers, control valves, and strainers, plus any open static lift. The pump is selected to deliver the design GPM at that head.

Why is there a fittings multiplier?

Elbows, tees, valves, and other fittings add friction beyond the straight pipe length. Rather than tabulating each fitting's equivalent length, this tool multiplies the straight-pipe friction by a factor of about 1.3 for typical distribution, up to 1.7 for runs with many fittings. It is a quick estimate; a detailed design totals equivalent lengths fitting by fitting.

How is the pump brake horsepower estimated?

Brake horsepower equals flow in GPM times total head in feet divided by 3960, then divided by the pump efficiency. This tool assumes 70 percent efficiency, so BHP equals GPM times head divided by 3960 divided by 0.70. The 3960 constant comes from the water horsepower formula for water at standard density.

Does a closed loop include static elevation?

In a closed loop the down-leg recovers the static lift of the up-leg, so building height does not add to pump head; you leave static elevation at zero. Static elevation only counts in open systems such as a cooling tower, where water must be lifted to the tower basin. Enter the open lift in the static elevation field for those cases.

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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.

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