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Plumbing Demand & Hunter's Curve Simulator

IPC Hunter's Curve demand calculation (WSFU aggregation), cold/hot branch sizing, service pipe sizing (IPC 604.4), static pressure budget, elevation loss (0.433 psi/ft), and booster pump check. Build fixture counts floor-by-floor to see total demand and available pressure at the highest fixture.

Pressure Budget at Highest Fixture

Street / Utility Pressure+65 psi

Service Pipe Loss (80 ft)-4.5 psi

Elevation Loss (24 ft @ 0.433 psi/ft)-10.4 psi

Meter & Backflow Losses-5 psi (est)

Residual at Fixture45.2 psi

Minimum Required15 psi (standard)

✓ Adequate street pressure — no booster required

Fixture Schedule (WSFU per IPC 2021 Table 604.1)

Fixture Type	Qty	Cold WSFU ea	Hot WSFU ea	Total WSFU
	4	2.5	0	10.0
	4	0.5	0.5	4.0
	4	1	1	8.0
	2	1.5	1.5	6.0
	2	2.5	0	5.0
TOTALS		24.0	9.0	33.0

Total Demand

28.1 GPM

33.0 WSFU

Cold Branch

24.0 GPM

24.0 WSFU

Hot Branch

13.7 GPM

9.0 WSFU

Service Pipe Sizing (IPC 604.4 — max 8 fps)

Pipe	ID (in)	Velocity (fps)	Status
¾"	0.811	17.41	Too fast
1"	1.049	10.41	Too fast
1¼" ✓	1.38	6.01	OK
1½"	1.61	4.42	OK
2"	2.067	2.68	OK
2½"	2.469	1.88	OK
3"	3.068	1.22	OK
4"	4.026	0.71	OK

Building & Site Parameters

Street Pressure65 psi

Service Run Length80 ft

Pipe loss: 4.5 psi in 1¼"

Meter Elevation0 ft

Highest Fixture Elevation24 ft

Elevation loss: 10.4 psi

Recommendation

Service pipe: 1¼" at 6.01 fps

Min. residual: 15 psi required
45.2 psi available → ✓ Adequate

IPC 2021 Sec. 604.1 (Hunter's method), Table 604.1 WSFU values, Sec. 604.4 velocity limit (8 fps), Sec. 604.6 minimum pressure (15 psi residential, 25 psi flush valve).