Wood stove fireplace inserts: are they worth it?

What a wood fireplace insert is

A wood insert is a wood stove built to fit inside the firebox of an existing masonry fireplace.¹ Its firebox sits inside an outer shell. Room air flows through the gap between the two, picks up heat and goes back into the room, so most of the heat reaches you instead of soaking into the brick behind it.¹ A decorative face plate closes the gap between the insert and the fireplace opening, and you still watch the fire through the glass door.

The EPA describes inserts as similar in function and performance to freestanding wood stoves.³ Their emissions are about the same as those of a stove of the same technology.²

Two close cousins:

• Hearth-mount stove: a regular wood stove set in front of or partly inside the fireplace and vented up its chimney. Only stoves whose certification label and instructions allow it can be used this way, and they need the same continuous stainless steel liner.¹
• Insert for a factory-built fireplace: metal prefab (zero-clearance) fireplaces are a separate case. Only an insert specifically designed and tested for your unit may go in, and few inserts are certified for that.³

Insert, open fireplace or freestanding stove

An open fireplace is built for watching a fire, not for heating. Tests have shown that a traditional fireplace can have negative energy efficiency: it pulls a large amount of warm air out of the house and gives little heat back, because it lacks gasketed doors, a designed combustion chamber and a heat exchanger.¹ Glass doors only cut air leaks when it is not in use. Of the upgrades for a masonry fireplace, only an insert or a hearth-mount stove is truly effective.¹

Efficiency and heat output

Certification is the big step. On average, advanced EPA-certified stoves are about one-third more efficient than conventional stoves and produce about 90% less smoke.¹ To compare models, the EPA's certified wood heater database lists each certified heater's emission rate and efficiency, and whether it meets the 2020 "Step 2" limit.⁴

Size by firebox, not looks. Firebox size is the best guide to heating capacity.¹ Too small and you run it flat out all winter. Too big and you turn it down too low, which makes smoky, polluting fires. An experienced wood heat retailer is usually your best source of sizing advice: bring a floor plan.¹

Location limits an insert. Wood heat works best from the main living area, with a chimney running straight up through the house interior, and an open-plan house is far easier to heat from one spot than one divided into small rooms.¹ An insert stays where the fireplace is. If that is a closed-off room or an outside wall, expect the heat to stay near that room.

What a wood insert costs

The insert is only part of the bill. Ask for each item as its own line on the quote:

1. The insert itself.
2. A full-height stainless steel liner sized to the insert's flue collar.¹
3. A thorough cleaning of the fireplace and chimney so no creosote remains, plus any masonry repairs the inspection turns up.¹
4. A hearth extension if the floor protection does not reach at least 450 mm (18 in.) in front of the insert. It must be permanently fixed: a hearth rug does not count.¹
5. The building permit and the final inspection.

We found no official Canadian price survey. As a rough US reference, a 2022 cost guide put the installation of a wood-burning insert at US$700 to US$6,500, and said a chimney liner adds about US$2,500 on average and up to US$7,000 in some communities.⁵ Prices in Canada, and since 2022, will differ. Get two or three itemized written quotes from certified installers.

Whether it pays off depends on the wood you burn and what it replaces. If you buy firewood, see how big a cord of wood is and use the face cord calculator to compare prices fairly.

Installation: the chimney liner is required

One rule applies to every fireplace insert: there must be a full stainless steel chimney liner from the insert's flue collar to the top of the chimney.¹ The liner:

• matches the flue to the size of the insert's collar;
• keeps flue gases away from the masonry so they stay hot and draw better;
• can be swept from the top, so the insert never has to be pulled out, which is costly and can damage the hearth.¹

In Canada, an insert must meet the ULC-S628 standard and a liner, rigid or flexible, must meet ULC-S635.⁶ After the liner work, you should receive a certificate of compliance for your insurer and your municipality.⁶

Have the chimney inspected first. An unlined masonry chimney can sometimes be upgraded with a certified stainless liner, but a bracket chimney (brick resting on wooden supports inside a wall, common in older rural houses) cannot be brought up to code and should be replaced.¹ Crumbling bricks or mortar near the top, or dark stains on the brickwork, call for an inspection right away.¹

Safety, codes and certification

Before you buy:

• The Canadian installation code for wood-burning appliances is CSA B365.¹
• Ask your municipal office about a building permit and tell your insurance agent your plan. Insurers vary widely, and most accept only safety-certified appliances.¹
• Choose an insert certified for emissions: Canadian jurisdictions treat the EPA standard and CSA B415.1 as equivalent.² Since 2020, new room heaters certified by the EPA must emit no more than 2.0 g/h of particles when tested with crib wood, or 2.5 g/h when tested with cordwood.⁸

In Quebec: every wood-burning appliance manufactured, sold, offered for sale or distributed in the province, fireplace inserts named, must meet CSA B415.1 or the EPA standard for particle emissions.⁹ It also forbids burning anything the manual or warranty does not allow.⁹ Cities can go further: Quebec City allows only the installation and use of certified appliances, and does not allow a new certified installation above 2.5 g/h unless it replaces an uncertified appliance.

Who a wood insert suits

An insert makes sense if:

• you have a sound masonry fireplace and chimney, ideally in the main living area of a fairly open house;
• you want to cut heating costs and still see the fire, which is why many Canadians choose them;¹
• you have, or can buy, a steady supply of dry firewood. Find local wood at firewood stands near you.

Look at a freestanding stove instead if:

• you have no masonry fireplace, or yours is in a poor spot for heating and a stove could sit centrally with its chimney inside the house;
• you want the most flexible and least expensive setup: a wood stove is the most common, flexible and inexpensive way to heat a space with wood.¹ See how to choose a wood stove.

Think twice if you only light a few fires a year for the mood: the insert and liner are a big outlay to recover. Check your city's rules too, as some, like Quebec City, now allow only certified appliances, with listed exceptions.¹⁰

Questions