All Tools
Engineering & Steam Systems

Total Dynamic Head (TDH) Boiler Feed Pump Calculator

Size discharge pressure and pump head in feet to overcome boiler pressure, safety valve lift, control valve loss, and economizer friction.

System Presets:

Boiler & Operating Parameters

Design inputs for steam output, pressures & line drops
PSI
%
%
Discharge Piping & Pressure Drops
ft
Deaerator Suction & NPSH Parameters
ft
ft
ft
%
%

Pump Sizing Output & Hydraulic Head

Real-time ASME dynamic calculations & cavitation analysis
Feed Pump Flow Rate
26.2
GPM (99.2 L/min)
Total Dynamic Head (TDH)
514
Feet of Liquid (213 PSI)
Shaft Brake Horsepower
5.0
BHP (3.7 kW Hydraulic)
Recommended Motor
7.5 HP
NEMA Frame (5.5 kW IEC)
NPSH Cavitation Margin (NPSHA - NPSHR) Safe Margin
NPSHA is 16.5 ft vs NPSHR of 8.0 ft (Margin: +8.5 ft / 2.06x ratio). Suction static elevation is safe from boiling cavitation.
System Flow Schematic (P&ID) Live Hydraulics
Hydraulic Component Pressure (PSI) Head (Feet)
Boiler Design Safety Pressure (+3%) 154.5 PSI 372.9 ft
Feedwater Control Valve Drop 20.0 PSI 48.3 ft
Economizer Heat Recovery Coils 15.0 PSI 36.2 ft
Discharge Piping & Check Valve Loss 10.0 PSI 24.1 ft
Static Elevation Lift 6.2 PSI 15.0 ft
Total Feed Pump Discharge Target 205.7 PSI 514.0 ft

Calculating Total Dynamic Head for Boiler Feed Water

Total Dynamic Head (TDH) is the total equivalent height of liquid column the feed pump must generate. To reliably feed water into an operating steam boiler, the pump discharge pressure must significantly exceed the normal operating steam pressure. Key pressure drops include: (1) Boiler operating pressure plus a 3% safety valve setting margin; (2) Feedwater regulating control valve pressure drop (typically 15 to 30 PSI across the valve travel); (3) Economizer or feedwater heater friction drop (10 to 20 PSI); (4) Piping, check valves, and strainer losses (5 to 15 PSI); and (5) Static elevation lift between pump centerline and boiler drum water level. TDH in feet is computed as (Delta-P in PSI x 2.31) / Specific Gravity.

Master Boiler Feedwater Equations:
1. Base Evaporation: Mass_steam (lb/hr) = BHP x 34.5
2. Feed Mass Flow: Mass_feed (lb/hr) = Mass_steam / (1 - Blowdown_fraction) x Safety_Factor
3. Volumetric Flow: GPM = Mass_feed / (500 x Specific_Gravity)
4. Total Dynamic Head: TDH (ft) = [P_discharge (PSI) - P_suction (PSI)] x 2.31 / Specific_Gravity
5. Deaerator NPSHA: NPSHA (ft) = H_static (elevation above pump) - H_suction_friction (ft)
6. Pump Shaft Power: BHP_pump = (GPM x TDH x Specific_Gravity) / (3,960 x Pump_Efficiency)
ASME Section I Code Guidelines
Boilers with more than 500 sq ft of heating surface require at least two independent means of feeding water. Each feed source must supply sufficient water to maintain safe operating levels when firing at full burner capacity.
Deaerator Elevation Standards
Because water in the deaerator vessel is at saturated steam conditions, the storage tank must be physically elevated on structural steel to provide sufficient static liquid column (typically 12 to 24 feet) to prevent pump cavitation.
Minimum Flow Recirculation
Multistage centrifugal feed pumps generate rapid internal friction heat at low flow. An automatic minimum-flow bypass line back to the deaerator prevents liquid flashing and destructive thermal seizure when modulating valves throttle back.

Boiler Feedwater Calculators & Engineering Tools

Explore specialized calculators for flow rate conversion, TDH summation, deaerator sizing, and motor specifications.

Boiler Horsepower to GPM Calculator Convert Boiler Horsepower (BHP) to feedwater flow rate in GPM. Includes continuous blowdown all... Total Dynamic Head (TDH) Boiler Feed Pump Calculator Calculate Total Dynamic Head (TDH) in feet and PSI for boiler feed pumps. Accounts for drum pre... NPSH Boiler Feed Pump Calculator Determine Net Positive Suction Head Available (NPSHA) and cavitation margin for boiler feed pum... Boiler Feed Pump Motor Sizing Calculator Calculate hydraulic water horsepower (WHP), pump shaft brake horsepower (BHP), and recommended ... Boiler Feedwater Flow Rate Calculator Calculate total boiler feedwater mass flow (lb/hr, kg/hr) and volumetric flow rate (GPM, m3/hr)... Deaerator Height & NPSH Calculation Calculate minimum required deaerator storage tank elevation above boiler feed pump suction cent... Steam Boiler Feed Pump Discharge Pressure Calculator Calculate pump discharge pressure in PSIG and bar needed to inject water into high-pressure ste... Multistage Centrifugal Boiler Feed Pump Sizing Size multistage centrifugal pumps for high-pressure boiler feedwater service. Calculate impelle... Continuous vs Intermittent Boiler Feed Sizing Comparison Compare pump sizing for continuous modulating feedwater control vs intermittent on-off float sw... Boiler Blowdown Rate & Makeup Water Capacity Calculator Calculate required boiler blowdown percentage and makeup water flow rate based on feedwater TDS... Feedwater Control Valve Pressure Drop Calculator Calculate pressure drop (Delta-P) across modulating boiler feedwater control valves to ensure p... How to Calculate Boiler Feed Pump Capacity Complete engineering guide on sizing boiler feed pumps: step-by-step formulas for flow rate (GP...
Related Engineering & Industrial Calculation Tools
G-Code Speeds & Feeds Calculator Roof Rafter & Truss Calculator Cubic Yard & Concrete Calculator Pool Salt & Chemistry Calculator Recessed Lighting Layout Calculator All 24 Micro-Niche Tools