Quick answer
A typical Ontario home spends around $1,800 a year on gas heat, but almost all of it lands between December and March, so no single monthly figure is useful. Work out your own in about five minutes from your Enbridge bill: subtract a summer month's usage from a winter month's, then multiply by the per-cubic-metre rates printed on the bill.
The cost to run a gas furnace in Ontario is the cost of the gas it burns plus the electricity its blower uses, and both appear on bills already sitting in your inbox. Rather than quote an average that will not match your house, here is how to get your own number and what moves it up or down.
Work out your own monthly heating cost
- Find the cubic metres (m³) used on each Enbridge Gas bill for the past 12 months. It is in the usage section, not the dollar total.
- Take a summer month — July or August — as your baseline. That usage is hot water, cooking and the dryer, with no heating in it.
- Subtract the summer baseline from a winter month's usage. What is left is roughly the gas your furnace burned that month.
- Multiply by the per-cubic-metre charges printed on your bill: the gas supply rate plus delivery and transportation. The fixed monthly customer charge stays the same whether you heat or not.
- Add the electricity the system uses. The blower, inducer and controls run on your Burlington Hydro, Oakville Hydro or Alectra account at whatever time-of-use or tiered rate you are on.
Do that for December through March and you have your real heating season instead of an average of somebody else's house. Rates change at each regulatory adjustment, so always use the figures on your latest bill rather than one from last winter.
What drives your gas heating bill
- The building envelope, which swamps everything else. A pre-war brick house in Dundas with no wall insulation and a 2018 build in Binbrook of identical floor area are not in the same conversation.
- Efficiency. An older mid-efficiency furnace sends a large share of its heat up the chimney. For a typical home spending around $1,800 a year on gas heat, moving to a high-efficiency unit saves in the range of $360–$450 a year, which is $5,400–$6,750 across 15 years — our high-efficiency furnace guide shows the working.
- Thermostat behaviour, which is the lever you control daily. Is it cheaper to leave the heat on all day settles the argument that usually comes with it.
- Exposure. Wind matters as much as temperature. Homes above the escarpment in Waterdown and up on the Hamilton Mountain sit in a colder, windier band than the lakeshore strip through Bronte and south Burlington.
- Duct losses. Leaky ducts running through an unheated crawlspace or a garage ceiling throw away a meaningful share of what you paid to produce.
- Blower type. A furnace with an ECM blower draws considerably less electricity than an older PSC motor, and the gap widens if you run the fan continuously.
How gas compares with the alternatives
Natural gas remains the cheapest common way to make heat in this province per unit of energy delivered, which is why so much of the region runs on it. Electric resistance heat — baseboards, or the backup element in an air handler — is the most expensive. A heat pump sits between them, moving several units of heat for each unit of electricity, so it competes well in mild weather and gives ground as temperatures fall. Which one wins on your bill depends on your rates and your house; heat pump versus furnace in Ontario works the comparison through properly.
Cutting the running cost without buying equipment
- Change the filter on schedule. A restricted filter makes the blower work harder and can trip limits that waste a cycle's worth of gas.
- Book the annual tune-up. Burner adjustment, a clean flame sensor and a correct temperature rise keep a furnace at its rated efficiency rather than drifting below it.
- Seal accessible duct joints in the basement with mastic or foil tape, and insulate any duct running through unheated space.
- Use a setback schedule instead of one fixed temperature, and let a smart thermostat handle the recovery timing.
- Check the humidifier bypass damper twice a year. Left open through the summer it is a straight loss of conditioned air.
If the bill looks wrong for the house
A furnace past 15 that burns noticeably more gas each winter is telling you something, and so is a bill that jumped without a change in weather or rates. Weigh a replacement against what you already spend on repairs and against current programs — furnace-only upgrades typically see $500–$1,500 back, and our furnace rebate page lists what is open right now. We handle the paperwork either way.
ZK Mechanical will look at your actual gas usage alongside the furnace in your basement and tell you whether the answer is a tune-up, a duct repair or a replacement, with the price in writing before anything starts. Call (647) 801-1252, browse our heating services, or send us your question.