Oil Boilers

Reliable Heat When You Need It.

Oil boilers power hydronic systems in locations without natural gas service. By burning heating oil, these boilers provide consistent warmth for homes and businesses, from basic cast iron models to advanced high-efficiency condensing units.

What Are Oil Boilers?
Oil boilers are heating systems that combust fuel oil to heat water or steam for space heating. A burner atomizes fuel through a nozzle, ignited at a combustion chamber, transferring heat via a heat exchanger into the building’s piping network.

Advantages of Oil Boilers

• Fuel availability in rural or off-grid areas without gas lines.
• High heat output per gallon of fuel, offering powerful performance in cold climates.
• No reliance on electricity for fuel delivery during power outages when paired with gravity-fed tanks.
• Durable construction with cast iron or stainless heat exchangers for long service life.

Types of Oil Boilers

• Standard-efficiency cast iron boilers for straightforward hydronic installations.
• High-efficiency condensing oil boilers that reclaim heat from combustion gases.
• Combi oil boilers providing both space heating and domestic hot water.
• Vertical or horizontal configurations to accommodate mechanical room constraints.

Choosing the Right Size

• Perform a heat loss calculation to determine the building’s BTU requirement.
• Match boiler output to calculated load; oversizing leads to short cycling, undersizing leads to inadequate heat.
• Factor in system piping, radiation type, and distribution zones for accurate sizing.
• Consult manufacturer’s sizing guides to select the correct model and capacity.

Installation Tips

• Locate the boiler close to the oil tank and burner to minimize line lengths.
• Install an oil burner control system and safety valves, such as those in the Oil Burner Controls category.
• Ensure adequate combustion air supply, especially in sealed mechanical rooms.
• Use flue connectors and chimneys rated for the high temperatures of oil combustion.

Maintenance Best Practices

• Change oil filters annually to prevent fuel pump damage.
• Service burner assemblies each season, cleaning nozzles and checking combustion quality.
• Inspect and clean the boiler’s fire side and flue passages to maintain heat transfer.
• Test safety controls and purge valves to ensure safe boiler operation.

FAQs about Oil Boilers

What is AFUE and why does it matter?
AFUE (Annual Fuel Utilization Efficiency) measures how effectively a boiler converts fuel into heat. Higher AFUE reduces operating costs.

How often should oil boiler nozzles be replaced?
Nozzles wear from heat and fuel contaminants; replacement every 1,500–2,000 hours keeps combustion optimal.

Can an oil boiler provide domestic hot water?
Combi models include an integrated heat exchanger for hot water, or an indirect tank can be added for water heating.

What maintenance prevents boiler corrosion?
Regularly replacing the anode rod in indirect tanks and purging condensate traps on condensing boilers prevents corrosion.

Are condensing oil boilers worth the investment?
Condensing units recover latent heat and can reach up to 90% AFUE, delivering significant fuel savings over time.

What safety controls are essential for oil boilers?
Low-water cutoffs, pressure relief valves, and flame safeguards are critical to prevent unsafe operating conditions.

How to troubleshoot ignition issues?
Check nozzle spray pattern, combustion air supply, and perform a combustion analysis to verify correct fuel-air mix.