Cottage Generator Sizing Guide for Ontario: Portable vs Standby, Watts, and Fuel
A cottage without power in a Georgian Bay winter is a cottage with a very expensive countdown timer. If you're sizing a generator for a property in Collingwood, Blue Mountains, or anywhere on the escarpment, here's the practical version — not the brochure version.
Why a Generator at All
Hydro outages in southern Georgian Bay are routine in winter — ice storms, wind events off the bay, and tree falls on rural lines take out power for hours or days. For an occupied cottage that's an inconvenience. For a vacant one, it's how pipes burst.
Without heat, a cottage interior can drop below freezing in 6–12 hours in a January cold snap. A furnace blower draws a few hundred watts; without that blower, even a propane or oil system can't distribute heat. A generator solves that problem for under $10k installed.
Sizing: The Math That Matters
Generator sizing has two numbers per device: running watts (steady-state draw) and starting watts (surge when a motor kicks on). Your generator must handle the sum of all running watts plus the largest single starting surge at the same time.
| Load | Running watts | Starting watts |
|---|---|---|
| Furnace blower (gas/propane) | 300–600 | 1,200–1,500 |
| Well pump, 1/2 HP | 1,000 | 2,500–3,000 |
| Well pump, 3/4 HP | 1,500 | 3,500–4,000 |
| Fridge (full-size) | 150–200 | 800–1,200 |
| Electric hot water (40-gal tank) | 4,500 | 4,500 |
| Sump pump | 800 | 1,300–2,200 |
| LED lights, outlets (estimated) | 500 | 500 |
| Central AC (3-ton) | 3,500 | 7,000–9,000 |
A practical winter-survival cottage (furnace + well + fridge + lights + sump) adds up to about 2,000 running watts with a peak surge of about 5,500 watts when the well pump starts while everything else is running. A 7,500-watt generator covers this comfortably.
If you want to run the whole property in summer including AC and electric hot water, you're in 12,000–14,000-watt territory — which is standby generator territory, not portable.
Portable vs Standby: The Real Tradeoff
Portable
$1,000–$3,000 for a 5,500–7,500-watt unit. You store it, roll it out during an outage, run an extension cord to the furnace / fridge, or plug it into a transfer switch.
Works when:
- You're physically at the cottage
- You can get there in under 6 hours
- Short outages in occupied summer months
Fails when:
- Power cuts at 2am in January, nobody there
- Gasoline has gone stale from sitting
- Extension cords don't reach hard-wired loads
Standby (automatic)
$6,000–$15,000 installed. Runs on propane or natural gas, wired to an automatic transfer switch. Detects the outage in seconds and fires itself up — no human required.
Works when:
- The cottage is empty and the power cuts
- Long outages (self-runs for days on propane)
- Freeze risk is real — furnace stays on automatically
Downsides:
- Higher upfront cost
- Needs propane/NG supply + ESA inspection
- Annual service and battery replacement required
For a cottage empty Monday through Thursday in winter, a portable generator in the shed does nothing. Standby is the right answer unless the property is full-time occupied.
Fuel Choice
Propane (most cottages)
A 420-gallon tank runs a 10 kW standby generator about 5–7 days continuously. No tank staling, no carburetor gumming. Our pick for 90% of Ontario cottages.
Natural gas (if line available)
Cheapest fuel, infinite supply while the NG grid is up. Most cottage properties don't have a line. If yours does, this is the obvious choice.
Gasoline (portables only)
Add stabilizer and run the generator once a month. Stale gas is the #1 reason portables fail when you need them.
Diesel
Common on older installs. Cold-weather gelling below -15°C is a real problem on the escarpment. Only consider if the infrastructure is already there.
Placement and Code Rules
Ontario standby generator installs require an ESA inspection plus an electrical permit, and the unit must meet CSA placement standards:
- At least 3 feet from any window, door, or air intake.
- At least 5 feet from combustibles (wood siding, fences, sheds).
- Municipal setback from property line varies — commonly 1 metre in Collingwood, Blue Mountains, and Meaford. Check your local zoning bylaw.
- Concrete pad or manufacturer-approved stand, level and drained.
Never run a portable generator inside a garage, under a deck, or in any enclosed space. Carbon monoxide kills a handful of Ontario cottage owners every winter — at least one is always someone who thought "cracking the garage door" was enough. It is not.
Ongoing Maintenance
A generator you don't maintain is a generator that won't start when you need it. The basics:
- Monthly exercise cycle (most standby units do this automatically, but confirm it's enabled).
- Annual oil + filter change and battery load test — $200–$400 from a qualified tech.
- 5-year battery replacement (standby units). Dead battery = unit won't start the engine.
- Clear snow from air intakes after heavy storms — a drifted-over generator can starve for air and fail to start.
Generator at your cottage but nobody there when it's needed?
Our ChaletGuard monitoring includes power-outage alerts with 3-day battery backup. You'll know the moment hydro drops, whether the generator fires, and whether the furnace starts running on backup. If something goes wrong, we coordinate a local contractor on your behalf.