Wood insert and liner for a 35' chimney

[cliffdweller]

Hi, nice to meet you all on the hearth.com forums.

I'm in the process of buying my first wood stove, and would appreciate any input or advice from the experienced burners around here. This site has been a great resource for me already; thanks to all of you who have contributed.

This will be my first winter in a new home, and I'd like to install a wood insert in the basement's open fireplace. We have an oil furnace, but the basement is big, largely uninsulated, and has few HVAC vents. I'm hoping that a wood stove run regularly at a low level will make a nice supplement, and make the basement a more livable space. Plus, I just like wood fires. I'm in the southern part of New York state, borderline climate zone 4/5. The house is built into a steep hillside, so it's irregularly shaped and quite tall.

The basement itself is about 1000 ft^2, open plan, half of which is double-height which creates a sizable volume. Exterior walls are largely uninsulated masonry block, which I will insulate, but maybe not in time for this winter. The fireplace is also masonry, in an exterior wall. The length of the flue (measured from fireplace damper to flue top) is just over 35', straight up with no bends.

My local stove shop pointed me towards a Blaze King Sirocco 25, which they want to install with a 40' SS flexible uninsulated liner. I'm leaning towards taking their stove recommendation -- I like what I've read about the insert and think it could be a good fit as a constantly low-burning supplemental heat source. But the uninsulated liner gave me pause, since all of the BK people here on the forum take liner insulation as a given. When I asked, they said it would add $1000 to the cost of the already expensive, extra-long liner.

My question is: because my flue is so long, will having an insulated liner be more important, or less important? Do you think I could try uninsulated first and insulate it if there's an issue? Is there anything else I should make sure they're doing as part of the install?

Also do you think the Blaze King is a good fit? I'm not sure how the lower flue gas temps of a BK would affect the draw in such a long, potentially uninsulated, flue.

If there's any other relevant information please let me know; I'm happy to provide it. I'm new, and I really want to get this right. Thanks in advance.

 

[begreen]

Given the description, my first concern is draft. If the basement is a negative pressure zone, especially when the furnace is running, but also if a clothes dryer or exhaust fan is on upstairs, then this could be an issue. Was the fireplace inspected for safety when the house was purchased? Have you had any fires in the fireplace?

Given the height of the chimney, an insulated liner will help reduce creosote buildup, especially with a stove that has cooler flue temps to start with. It might also be a candidate for a 5" liner if BK permits this.

Uninsulated basements typically lose about a third of the heat through the walls. I suspect that the stove will not be running low and slow very much. For this reason, it's worth considering a non-cat with higher flue temps.

 

[cliffdweller]

Hi begreen, thanks for the reply. Yes we got a chimney inspection and they said it's in good shape.

I've had a few dozen fires in the fireplace. Draft hasn't been an issue there. But I have definitely noticed that the next day, the basement smells more like fireplace than I'd consider the normal. So it's likely I'm getting some kind of downdraft when the fireplace is cool.

There is definitely some negative pressure; cracking a window will get you a reliable inward breeze. The furnace and dryer are in the basement in a separated utility room. Definitely not air sealed though.

So is the concern that with a tall chimney, low flue temps, and negative basement pressure, that I could have trouble getting a draft going? I was thinking about it the other way -- once it get going the draft might be extreme. That's why I had ruled out some non-cats (VC Montpelier II in particular, as it has fewer air controls). But definitely let me know if my thinking on that wasn't right.

 

[begreen]

The concern is draft reversal when the fire and flue gases have cooled down. It could introduce CO into the room. This would apply to cat and non-cat inserts. It's not all that uncommon with basement installs in tall houses.

 

[cliffdweller]

That makes sense. I do think I've experienced that effect a little already through the open fireplace. If an insulated flue liner will help mitigate that, then it sounds like a no-brainer.

If there's anything else you can think of that I should consider when doing the basement stove install, I'd be all ears. Thanks a ton for your time. Definitely excited to enter the world of wood burning.