Some useful numbers to help get you from here to there:
Multiply  By  To Obtain  
Atmosphere  29.92  Inches of mercury  
Atmosphere  33.92  Feet of water  
Atmosphere  14.7  Pounds per sqare inch  
Atmosphere  1.058  Tons per square foot  
Barrels (oil)  42  Gallons  
Boiler Horsepower  33,474  Btu per hour  
Boiler Horsepower  34.5  Pounds water evaporated from and at 212F  
BTU  778  FootPounds  
BTU  0.000393  Hoursepowerhours  
BTU  0.000293  Kilowattshours  
BTU  0.0010307  Pounds water evaporated from and at 212F  
BTU per 24 hr  0.00000347  Tons of referigeration  
BTU per hour  0.00002986  Boiler horsepower  
BTU per hour  0.000393  Horsepower  
BTU per hour  0.000293  Kilowatts  
BTU per inch per sq. ft. per hour per F  0.0833  Btu per foot per sq. ft. per hour per F  
Cubic feet  1,728  Cubic Inches  
Cubic feet  7.48052  Gallons  
Cubic feet of water  62.37  Pounds at (at 60F)  
Cubic feet per minute  0.1247  Gallons per second  
Feet of water  0.881  Inches of mercury (at 32F)  
Feet of water  62.37  Pounds per square foot  
Feet of water  0.4335  Pounds per square inch  
Feet of water  0.0295  Atmospheres  
Feet per minute  0.01136  Miles per hour  
Feet per minute  0.01667  Feet per second  
Footpounds  0.001286  Btu  
Gallons (U.S.)  0.1337  Cubic feet  
Gallons (U.S.)  231  Cubic inches  
Gallons of water  8.3453  Pounds of water (at 60F)  
Horsepower  550  Foot pounds per sec  
Horsepower  33,000  Footpounds per min  
Horsepower  2,546  BTU per hour  
Horsepower  42.42  BTU per minute  
Horsepower  0.7457  Kilowatts  
Horsepower (boiler)  33,475  BTU per hour  
Inches of mercury (at 62F)  13.57  In. of water (at 62F)  
Inches of mercury (at 62F)  1.131  Ft. of water (at 62F)  
Inches of mercury (at 62F)  0.4912  Pounds per sq in.  
Inches of mercury (at 62F)  70.73  Pounds per sq ft.  
Inches of water (at 62F)  0.07355  Inches of mercury  
Inches of water (at 62F)  0.03613  Pounds per sq in.  
Inches of water (at 62F)  5.202  Pounds per sq ft.  
Inches of water (at 62F)  0.002458  Atmospheres  
Kilowatts  56.92  BTU per minute  
Kilowatts  1.341  Horsepower  
Kilowattshours  3,415  BTU  
Latent heat of ice  143.33  BTU per pound  
Pounds  7,000  Grains  
Pounds of water at 60F  0.01602  Cubic Feet  
Pounds of water at 60F  27.68  Cubic Inches  
Pounds of water at 60F  0.1198  Gallons  
Pounds of water evaporated from and at 212F  0.284  Kilowatthours  
Pounds of water evaporated from and at 212F  0.381  Horsepowerhours  
Pounds of water evaporated from and at 212F  970.4  BTU  
Pounds per square inch  2.309  Ft. of water (at 62F)  
Pounds per square inch  2.0416  In. of mercury (at 62F)  
Tons of refrigeration  12,000  BTU per hour  
Tons of refrigeration  200  BTU per minute  
Tons (Long)  2,240  Pounds  
Tons (Short)  2,000  Pounds  
Watts  44.26  Ft. pounds per min  
Watts  0.7378  Ft. pounds per sec  
Watts  0.05692  BTU per minute  
Watthours  3.415  BTU  
Watthours  2,656  Ft. pounds 
. 

EDR to Pounds of condensate per hour (Divide EDR by 4) • EDR to GPM (Multiply EDR by 0.0005) EDR to BTUH at 1 psig steam pressure (Mulitply EDR by 240) • EDR to boiler horsepower (Divide EDR by 140) EDR to Grate Area in Square Feet (Divide EDR by 196) • BTUH to EDR (Divide BTUH by 240) BTUH to Boiler Horsepower (Divide BTUH by 33,475) • PSIG to Feet of Water (Multiply PSIG by 2.31) Boiler Horsepower to Pounds of Condensate per hour (Multiply BHP by 34.5) • Boiler steaming rate (regardless of type or manufacturer) = 1/2 GPM per 1,000 sq. ft. EDR 

Fuel Values:  Maximum copper tubbing flow rates and BTUH loads (at 20° Δ T)  
No. 1 fuel oil = 135,000 BTU per gallon  1/2" = 11/2 GPM = 15,000 BTUH  
No. 2 fuel oil = 140,000 BTU per gallon  3/4" = 4 GPM = 40,000 BTUH  
No. 4 fuel oil = 155,000 BTU per gallon  1" = 8 GPM = 80,000 BTUH  
No. 5 fuel oil = 150,000 BTU per gallon  11/4" 14 GPM = 140,000 BTUH  
No. 6 fuel oil = 153,000 BTU per gallon  11/2" = 22 GPM = 220,000 BTUH  
Natural gas = 1,000 BTU per cubic foot  2" = 45 GPM = 450,000 BTUH  
Natural gas = 100,000 BTU per Therm  
Manufactured gas = 550 BTU per cubic foot  
Propane = 2,250 BTU per cubic foot  Fahrenheit to Celsius = (°F  32°) / 1.8 Celsius to Fahrenheit = °C x 1.8 + 32° 

Propane = 92,000 BTU per gallon  
Electricity = 3,415 BTU per kWh  
Anthracite coal = 13,700 BTU per pound  Stream Fan Coil loads in Pounds of Steam per hour =  
Bituminous coal = 12,500 BTU per pound  CFM X ΔT of air (in °F) / 800  
Wood = 14,000,000 BTU per mixed cord  


EDR FOR HOT WATER RADIATORS:  
Average water temp °F  Output in BTUH per sq ft. EDR  
150  110  
155  120  
160  130  
165  140  
170  150  
175  160  
180  170  
185  180  
190  190  
195  200  
200  210  
205  220  
210  230  
215*  240  
220  250  
*(also for 1 psi steam)  
Pump Head Rule of Thumb:  
Measure longest run in feet. Allow 6 feet of pump head per 100 feet (this includes an allowance for the fittings and the boiler)  