Power Vent vs Chimney Vent: Which Water Heater Does Your Home Need?

Short answer: If your water heater vents into a sound chimney that still works well, a chimney vent tank is the simplest, lowest-cost swap. If your chimney is gone, damaged, or now vents the water heater alone after a furnace upgrade, a power vent tank that exhausts through the wall is usually the better fit. Across the GTA and Southern Ontario, both start at $2,195 installed with Mr. Heating & Home.

How each one works

Chimney vent (also called conventional or natural draft): hot exhaust rises up a metal vent into your chimney on its own. No fan, no electricity.

Power vent: a small fan on top of the tank pushes exhaust through a plastic vent pipe and out a side wall of the house. It needs a standard electrical outlet nearby.

Side by side

The "orphaned" water heater problem

This is the most common reason homeowners across the GTA and Southern Ontario switch. In many older homes in Toronto, Mississauga, Oakville, Markham, Durham Region, Kitchener-Waterloo, Guelph and Peterborough, the furnace and water heater once shared one chimney. When the furnace is replaced with a high-efficiency model, which vents through the wall in plastic pipe, the water heater is left alone in a chimney built for two.

A chimney that's too large for one small appliance can draft poorly, especially in cold weather. That lets exhaust linger and moisture condense inside the chimney. The two usual fixes are:

• Line the chimney with a properly sized liner and keep a chimney vent tank, or
• Switch to a power vent tank and stop using the chimney for the water heater.

We check your venting before install day and recommend the safer, more cost-effective option for your home.

Signs your chimney vent setup needs attention

• Your furnace was upgraded and the water heater still vents into the chimney
• Rust, water stains or white residue around the vent or draft hood
• Crumbling brick or mortar where the chimney meets the roof
• A smell of exhaust near the water heater

If you smell gas or exhaust, leave the house and call your gas utility's emergency line right away.

Which should you choose?

Keep chimney vent if your current tank vents well into a sound chimney that's lined or correctly sized, and you want the simplest swap that works through a power outage.

Choose power vent if you've upgraded your furnace, your chimney needs repair, you're finishing the basement and want the tank somewhere else, or you'd rather not maintain a chimney at all.

Frequently asked questions

Is a power vent water heater better than a chimney vent?

Neither is better in every home. Power vent is more flexible and doesn't depend on a chimney. Chimney vent is simpler and works without electricity. The right choice depends on your chimney and your furnace.

Does a power vent water heater work in a power outage?

No. The fan needs electricity, so a power vent tank can't heat new water during an outage. The hot water already in the tank is still usable.

How much does it cost to switch from chimney vent to power vent?

Our power vent tanks start at $2,195 installed. Converting may also need new vent pipe run to an outside wall and an electrical outlet near the tank. We quote any extra work before we start.

Shop tank water heaters · See 2026 replacement costs · Call 905-418-2629