Tool · Running cost
What does the boiler cost to run each year?
Enter the boiler input rating, the hours it fires in a year, the current AFUE and a comparison AFUE — then your own fuel price. The tool shows annual fuel use and cost, the formula with your numbers substituted, and exactly which published conversions it used.
Annual running cost · inputs
Input, not output: the fuel side of the rating plate (MBH × 1,000).
The hours the burner actually fires in a year. The result scales directly with this number.
No default price is assumed. The dollar result appears only when you enter the price from your own bill or invoice.
Enter the four inputs
The calculation needs the boiler input rating, annual run hours and both AFUE figures. The fuel price is optional — without it the tool still shows fuel energy, just not dollars.
How this works
The formula, step by step
Four lines of arithmetic, each one checkable. No fuel price and no efficiency value is assumed — every figure comes from the user or from a published conversion.
01
Annual fuel input
BTU/year = input (BTU/h) × annual run hours
The input rating is the fuel side of the rating plate — an MBH figure multiplied by 1,000. Run hours are your estimate of burner-on time.
02
BTU to gigajoules
GJ = BTU ÷ 1,000,000 × 1.0551
The 1.0551 is the Canada Energy Regulator's published conversion: 1 million BTU = 1.0551 GJ. It is a unit conversion, not an efficiency assumption.
03
Fuel to dollars
cost = fuel units × your price per unit
Natural gas is billed in gigajoules on a FortisBC bill; propane is billed per litre, and the CER publishes 1 m³ of propane = 25.53 GJ (1 m³ = 1,000 L). The price is always yours — the tool assumes none.
04
Comparing two AFUE values
fuel₂ = fuel₁ × (AFUE₁ ÷ AFUE₂)
The comparison holds delivered heat constant: the higher-rated boiler burns less fuel to heat the same building. This is the standard reading of AFUE, not a savings guarantee.
What AFUE is, in the regulator's words
Natural Resources Canada defines AFUE as Annual Fuel Utilization Efficiency and sets the federal standard for household gas boilers at 90% or higher for hot-water systems and 82% for low-pressure steam, tested under CAN/CSA-P.2-13. The rating is a seasonal test figure, not a meter reading: a condensing boiler reaches its rated performance only when the system returns cool water, and a modulating boiler firing below rated input uses proportionally less fuel than the formula's full-rate assumption.
What the estimate is not
- Not a bill prediction — actual consumption depends on weather, the building, the controls and the boiler's modulation.
- Not a savings guarantee — it is an arithmetic comparison of two certified ratings at equal delivered heat.
- Not a sizing tool — boiler size comes from a heat-loss calculation, not from a running-cost estimate.
Sizing is covered in the heat-loss guide.
If a carbon-monoxide alarm sounds
- Leave the building immediately and get fresh air.
- Call 911. Do not go back inside until emergency services say it is safe.
- Have every fuel-burning appliance inspected before use.
Only after that, call ROMA about the boiler. Official guidance: Health Canada on carbon monoxide.
Sources and verification
- Natural Resources Canada — Gas boilers: household (AFUE definition and standard) · accessed September 9, 2026
- Canada Energy Regulator — Energy conversion tables · accessed September 9, 2026
- FortisBC — Gigajoules: how natural gas is measured · accessed September 9, 2026
Facts checked September 9, 2026. Last updated September 9, 2026. Technical reviewer: not yet assigned.
Want the running cost checked against your actual bills?
A consultation can compare the estimate with your real gas use and review the boiler's setup — the part of efficiency a calculator cannot see.
On-site service in Greater Vancouver, BC. ROMA lists “Open 7 days” on its site; call to confirm same-day availability.