Sizing Boiler Feed Units

Step 1 : Pump Flow Rate Sizing
Enter Load expressed as any of the following units in the drop-down list.	On/Off running pumps	Continuously running pumps
Boiler HP Sq. Feet EDR Lbs./Hour BTUs/Hour MBH Kilowatts (kW)	pump GPM	pump GPM
#1	#2
One or both of the results is LESS than 0.5 pump GPM. We advise you contact your Shipco representative. One or both of the results is GREATER than 500 pump GPM. We advise you contact your Shipco representative.
Step 2 : Boiler Feed Pump Receiver Size
Enter Total Load expressed as any of the following units in the drop-down list.	On/Off running pumps	Continuously running pumps
Boiler HP Sq. Feet EDR Lbs./Hour BTUs/Hour MBH Kilowatts (kW)	gross gallons	gross gallons
	#3	#3
Step 3 : Pump Discharge Pressure Sizing
Discharge Pressure of pumps based on the larger amount. This amount is either the Safety Relief Valve setting on boiler + 3% OR Boiler Operating Pressure + Valve Pressure Drops + Safety Margin.
1. Enter Vertical Lift.	Pumps running On/Off
feet of head	pump discharge psig
#4	#2, #7, #8
2. Enter Boiler Operating Pressure.	Pumps running Continuously (with stack economizer)
psi	pump discharge psig
	#5, #6, #7, #8
3. Enter Safety Relief Valve Setting on Boiler. (optional)	Pumps running Continuously (no stack economizer)
psi	pump discharge psig
#9	#5, #7, #8
Press "Reset All" to CLEAR ALL calculations and enter new values.

Notes

1. Each pump on a boiler feed unit is sized based on the total load of boilers fed by specific pump feeds at one time.
2. For boiler feed pumps running ON/OFF, the pumps are controlled by a boiler level controller.
3. The receiver size on boiler feed units is typically based on the total system load of all boilers fed by the boiler feed unit with 20 minutes GROSS storage. The size of boiler feed receivers are expressed in gross gallons. Make sure the inlet height is lower or equal to exisiting height on gravity return systems—water does not run uphill!
4. If boiler and boiler feed unit are on the same floor, enter a value of "0" for feet of head. If boiler is located on a floor above the boiler feed unit, enter vertical height (in feet) from the pump discharge of the boiler feed pump up to the inlet piping on the boiler.
5. Assumes pressure drop through modulating valve of 10 psig or less.
6. Assumes pressure drop through stack economizer of 20 psig or less.
7. Assumes proper discharge pipe size of a velocity of 10 ft/sec or less.
8. Pump discharge pressure MUST BE ABLE to overcome the boiler safety relief valve setting plus three percent of valve setting AND meet all state and local codes.
9. If the pressure differential between the boiler operating pressure and the setting of the safety relief valve on the boiler is greater than 20 psig, consider replacing the safety valve with one rated closer to the boiler operating pressure. Otherwise the motor horsepower of the boiler feed pumps will need to be oversized to provide a discharge pressure sufficient to overcome the rating of the safety relief valve on the boiler. The higher motor HP typically would require a more expensive pump and increases ongoing operating costs.

Additional Information

If condensate return temperature is 200°F or above (at sea level) check available NPSH to avoid potential cavitation problems.

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