Measured in API Gravity API = American Petroleum Institute Ranges from 0 to 99 degrees The lighter the oil, the higher the rating. 20 degrees = 7.77 pounds 40 degrees = 6.87 pounds These are measured with a hydrometer

1. 1
HVAC222 - Oil
Oil Characteristics
Oil Heat Calculations

2. 2
Fuel Oil Weight
• Measured in API Gravity
– API = American Petroleum Institute
– Ranges from 0 to 99 degrees
• The lighter the oil, the higher the rating.
– 20 degrees = 7.77 pounds
– 40 degrees = 6.87 pounds
• These are measured with a hydrometer

3. 3
Viscosity
• The resistance to flow (thickness of oil)
• Time required for an oil sample at a given temperature
to flow through a fixed restriction.
• Heavier oils have a higher restriction.
• As the temperature rises; viscosity goes down.

4. 4
Viscosity
• As the temperature drops, viscosity goes up.
– An outdoor oil tank needs to be protected from cold as the
viscosity can go so far up the oil will not flow through the
filter properly.

5. 5
Flash Point
• The temperature at which the oil will give off sufficient
vapor to support a flash fire (momentary, not
combustion).
• The lowest temperature vapors will ignite in the air
when exposed to flame.
• The maximum safe storage and handling temperature.

6. 6
Distillation Range
• Used as a measurement for lighter oils.
• It is the temperature at which oil will boil.

7. 7
Water and Sediment content
• Percentage of water and impurities in the oil.
• Heavier oils have more water and sediment.
• Water and sediment can cause:
– Interrupted flame
– Clogged burners

8. 8
Pour Point
• The lowest temperature at which oil can be poured.

9. 9
Types of oil
• #1 - Kerosene
• #2 - Home Heating Oil
• #4 - Industrial
• #6 - Bunker Oil

10. 10
#1 - Kerosene
• Characteristics
– BTU Rating: 132,900 to 137,000 BTU/Gal
– API Gravity: 38 to 45 degrees
– Weight: 6.95lbs / Gal
– Flash Point: 100 degrees
– Pour Point: 0 degrees
– Will vaporize at room temperature and can easily be ignited.

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#1 Kerosene
• Uses:
– Old style heating
– Space heaters
– Cleaning solvent
• Sometimes used in place of #2 oil or mixed into
outdoor tanks because of the lower pour point.
Flows better at low temperatures.

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#2 - Home Heating Oil
• Characteristics
– BTU Rating: 140,000 BTU/Gal
– API Gravity: 20 to 28 degrees
– Weight: 6.9 - 7.3 lbs / Gal
– Flash Point: 130 degrees
– Pour Point: 20 degrees
– Will not vaporize at room temperature and to ignite you must
add heat.

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#2 - Home Heating Oil
• Uses:
– Residential Home Heating
– Residential Hot Water
– Light Commercial Applications

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#4 - Industrial Oil
• Characteristics
– BTU Rating: 145,000 BTU/Gal
– API Gravity: 20 to 28 degrees
– Weight: 7.78 lbs / Gal
– Flash Point: 130 degrees
– Pour Point: 20 degrees
– Does not require pre-heating
– Industrial heat and power.

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#6 - Bunker Oil
• Characteristics
– BTU Rating: 153,000 BTU/Gal
– API Gravity: 8 to 15 degrees
– Weight: 8.44 lbs / Gal
– Flash Point: 50 degrees
– Pour Point: Can not pour

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Oil Heat Calculations
• BTU Output:
– The amount of heat being used to heat the space.
– Heating oil has a BTU content of 140,000 BTU’s per gallon.

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Oil Heat Calculations
• To determine how much heat a nozzle is capable of,
multiply the GPH of the nozzle times 140,000.
• Example:
– .75GPH Nozzle x 140,000 = 105,000 BTU
– .50GPH Nozzle x 140,000 = 70,000 BTU

18. 18
Oil Heat Calculations
• Examples
– 1.25GPH x 140,000 = 175,000 BTU
• These numbers are only accurate with a 100% efficient
furnace.
• These numbers only work if oil pressure is at 100 psi.

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Oil Heat Calculations
• Using the furnace efficiency percentage and accurate
BTU output can be calculated.
• Example:
– A furnace has a .50GPH nozzle and an efficiency of 80%.
– Knowing that 20% of the heat is going out the chimney the
70,000 btu’s will be lower.

20. 20
Oil Heat Calculations
• Example(cont)
– .50GPH x 140,000 = 70,000
– 70,000 x .80 = 56,000 btu/hr
– .50GPH x 140,000 x 20% = 56,000 btu/hr
– This means that 14,000 btu/hr are going up the chimney (20%
of 70,000).

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Calculating Air Flow
• The volume of air is defined as Cubic Feet Per Minute
(CFM)
• To calculate the CFM of a furnace the BTU’s must be
known.
• Q = The quantity of useable BTUS of a system.

22. 22
Calculating Air Flow
• Example: A furnace has a .50GPH nozzle and is 90%
efficient.
• Q = 140,000 x .50 x .90
• Q = 63,000
• Now take a supply duct temperature reading with the
burner and fan on.

23. 23
Calculating Air Flow
• Next take a return air temperature reading with the
burner and fan on.
• Subtract the return from the supply to get your Delta-T
(Temperature difference).
• Multiply this number by 1.08 (this is a constant).

24. 24
Calculating Air Flow
• The formula:
CFM = Q ÷ (∆T x 1.08)
CFM = 63,000 ÷ ((145-69)x 1.08)
CFM = 63,000 ÷ (76 x 1.08)
CFM = 63,000 ÷ 82.08
CFM = 767 CFM

25. 25
Calculating Air Flow
• This calculation can help the duct designer or
technician decide if the ductwork is undersized and can
also help determine if air conditioning can be added to
the ductwork.
• Air Conditioning requires 400CFM per Ton (12,000
BTU’s)