Fuel Oil Furnace and Boiler Sizes
Step 1: Using the map below, find your climate zone’s Required Heating Power, measured as BTUs per Square Foot.
Step 2: Using the Correction Factor table below, find your home’s Correction Factor.
Step 3: Multiply your home’s square feet by the Required Heating Power (from Step 1), and multiply that by the
Correction Factor (from Step 2) to find your recommended boiler size.
![Climates-Zone.jpeg](assets/blog/oil-central-heating/fuel-oil-furnace-and-boiler-sizes/Climates-Zone.jpg)
Correction Factor
For a building that you know has adequate insulation – No adjustment needed
For a building that has no insulation – Multiply BTU Requirements x 1.15
For a building in severe conditions only – Multiply BTU Requirements x 1.61
Other Considerations
- Air Infiltration: A drafty building is hard to heat. Make sure there are no gaps in the doors or windows of the building.
- House Floorplan: In general, it is harder to heat longer, narrower homes than shorter, squarer homes.
- Ceiling Height: If the ceiling is more than 14’ high, install ceiling fans to re-circulate the heat from the ceiling down onto the floor area.
- Heat Recovery: If the garage doors are left open a lot or opened and closed frequently you may need a more powerful heating unit. (Clean Burn)