Estimate target flow (GPM) and head (ft) for a hydronic circulator. Then pick a pump that meets the point on its curve.
If unsure, choose load + ΔT and we’ll compute GPM.
Use your boiler sizing result (space heat only) or a Manual-J value.
If you already know the needed loop flow, enter it here.
Used to compute GPM when basis = load. GPM ≈ BTU/h ÷ (500 × ΔT).
Single-loop adds boiler heat exchanger head to the calc.
Check the boiler manual for exact drop at your flow.
We’ll use typical inside diameters for the chosen material.
Supply out and return back to the boiler — longest loop.
We multiply straight length to estimate total equivalent length.
Target flow
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Computed from load & ΔT or entered GPM
Estimated head
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Hazen-Williams + fittings + boiler HX (if any)
Pipe velocity
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Goal ≈ 2–4 ft/s
Common pumps that often fit this point*
*Suggestions use approximate envelopes and speed scaling. Always verify your point on the manufacturer’s curve.
Disclaimer: Results are approximate and for preliminary selection only. Head loss is estimated using Hazen-Williams (typical C-values), equivalent length factors, and optional boiler heat-exchanger drop. Always confirm final selection using the manufacturer’s pump curves and project-specific details.