This improvement in the design of insert installations has improved their performance to the extent that today’s best fireplace inserts can be almost as efficient as free-standing wood stoves. If you already have an insert installed in a masonry fireplace, the addition of a stainless steel chimney liner can improve performance and is mandatory per the fire code legislation.
In the 29 years since the Canadian code changed to mandate full liners for inserts and hearthmounts, they have become among the most trouble-free of all wood heating installations. This is because the liner runs almost straight up from the insert flue collar, which is the most desirable arrangement for reliable draft. Cleaning the flue is a simple matter of removing the cap and running a brush down to the insert.
The reliability of an insert installation depends on a perfect installation. If the liner connection at the insert flue collar is faulty causing the liner to fail, the results can be very messy. Knowing all the ins and outs and pitfalls of insert installations is a job for professionals. Don’t make the mistake of thinking that installing an insert is a simple matter of running a liner up the chimney. Contact the most experienced insert installer you can find. You won’t regret the small additional cost.
Words of caution regarding stainless steel liners
One thing of importance to note is that the stainless steel liner must meet the stove manufacturer’s recommendations for installation, clearance and proper venting. That being said, certain older hearthmounted stove manufacturers have long gone out of business and it may be quasi-impossible to find user manuals.
Also, a majority of these older hearthmounted stoves are most likely not certified by a recognized safety authority such as ULC or Warnock Hersey. If that’s the case, the best approach would be to upgrade the hearthmounted stove to a newer, certified model.
Lastly, older hearthmounted stoves, for the most part, had larger vent openings, i.e. 7” or 8” and current legislation (CSA B365) allows for a maximum 6” stainless steel liner. Again, if a larger liner, say 8”, meets the stove’s recommendations for installation, clearance and proper venting with adequate draft, then there is no issue even though this conflicts with B365. As there can be ambiguity between the manufacturer’s recommendation and the actual legislation, we strongly recommend that you seek the services of a professional installer to discuss your needs.