Are insulated chimney liner and block-off plate essential?

[bonedoc]

Wood Stove Gurus:

I am about to have a FPX 33 Elite installed in an exterior masonry chimney.(not my first choice but the wife insisted; would have liked more radiant heat a'la Summit or Lopi Freedom.)

House is 2 stories so I estimate the chimney is at least 25-30' long.

My house is over 3000 sf with an open floor plan so the stove will be for supplemental heat. Still, I would like to get long burns and decent efficiency.

I have seen much talk about the importance of an "insulated" chimney liner, a block-off plate and even a damper.

My questions are:

1. How important are the insulation and block-off plate?

2. Are these customarily included in most professional installations or extra things that I MUST ask and pay extra for?

3. I am paying over $1000 for installation of a full-length chimney liner; should I assume this is insulated? Is there a particular brand to ask for?

Burned wood my entire childhood with an old Buck stove in the early 80s.....don't remember any of this.

Any and all info would be a big help as the insert is supposed to arrive tomorrow... Thanks.

 

[burntime]

If you want to get peak efficiency I am all for them. I paid for an install and they did not do it. I actually had a different issue... I had the internal masonary fireplace heating up...heating the block in the attic, the heat in the attic caused ice damning. I insulated and did a block off plate to combat the ice damning. The difference is amazing. It would be like driving a 5 speed on the freeway in 4th gear...not the most efficent. I can choke the stove down more to slow the burn, I have less accumulation in the chimney, and the heat stays in the home. Most important is the I think it is more safe with an added layer of chimney insulation. As for your buck stove...I had a slammer unit (cemi 2) that was the same way. You will appreciate it the first time you do your own chimney cleaning and do not have to remove the unit. 50 bucks for brush and poles and you can do it yourself in 5-10 minutes tops vs. spending 150 a year.

 

[edthedawg]

bonedoc,

I would recommend all 3, but you can't assume any of them will happen - esp at $1000 for the install, for both mat'l and labor.

Insulated Liner - If you haven't already talked w/ your installer specifically about an insulated liner, and they're supposed to install it tomorrow, you need to call them immediately. They may not have the insulated ones in stock, or the insulated kind may not fit into your chimney. If it's a straight shot bigger than 8" x 8", I'd expect it would fit, and you should go with it. It'll help immensely with reducing creosote condensation in that big, cold structure. IME, installers generally get the uninsulated type - cheaper to buy, more readily available, and easier to transport and install. At only $1000 I'd be very surprised if he was planning to go insulated.

Block off plate - definitely required - if your installer isn't putting one in, you really need to question him further. This is not an off-the-shelf item due to every fireplace being a little unique. Big piece of sheetmetal, custom-fit to your fireplace, with your liner run thru it, and preferably some extra insulation above it just for good measure (that is totally optional tho - better for inserts). I really hope you don't have to ask specifically for one - my town building inspector would have failed me without one. Cost is mostly labor - sheetmetal can be just about any flavor of steel. This should really already be included.

Damper - 25 to 30 feet of liner above the stove? I'd add one. It's the cheapest and easiest item on your list here. I think they cost about $15 ((broken link removed to http://www.northlineexpress.com/itemdesc.asp?ic=5CO-31320) - also available off the shelf at Home Depot or Aubuchons), assuming you have single-wall pipe off your stove. More if you're going w/ double-wall or something else fancy.

A note on dampers: If you don't need it, you just run wide open and forget it's there. If you do wind up needing it, it'll already be there and it's a happy day. If you do use it, be mindful of the flue-cooling you produce w/ it, and the extra creosote you may wind up condensing in the flue as a result. Just run it wide open (inferno mode) for 15-20 minutes once or twice a day and you'll burn out the nastiness.

And a note on liners: It is assumed that your liner will be capped at the top of the chimney flue, too - it shouldn't be loose fitting up there. You don't want the airspace between the liner and the masonry to be open and venting heated air up and out of the house. That wastes your energy and over-cools your liner... Just something to confirm during the install. Most commercially available liner kits include a cap of some sort - things tend to vary less up top vs. inside the firebox.

Good luck!

 

[BrotherBart]

The long and short of it is that spending over three grand and not insulating the liner and putting in a block off plate just does not make a lot of sense. The insert will work but you will forever wonder if it would work better with them installed. You should get it installed with them to obtain the best performance possible. Someone suggested a pipe damper, not possible with the FPX 33.

And you can bet that the installers aren't planning on insulation and a block off plate if they haven't mentioned them. Even to the point that they will argue that the block off plate isn't needed. If they balk at doing them now ask if they will come back and install the insulation and block off plate for parts only with no labor charge if the unit does not perform up to your expectations.

 

[edthedawg]

Ah - didn't do my homework - BB is correct - no damper for thet thar insert. Unless you really wanted to do something super-crazy (and you don't...). Definitely would be recommended to insulate above the blockoff plate - get all that heat out into the room, not just sent up around the liner...

 

[mellow]

Trust me, you WANT a block off plate, and you WANT your liner to be insulated PERIOD. You have an external chimney, your pipe is going to get cold and gather more creosote and not draft as well.

Trust me, I put a liner in last season, no insulation and no block off plate and had alot of trouble with backdraft and creosote buildup. This year I pulled it all out and insulated it and reinstalled with a block off and it is like night and day, when it comes to an external chimney you REALLY need to insulate.

Get on the phone ASAP and make sure you tell them you want it insulated, no matter what they say (some installers are lazy)!

 

[Lanningjw]

I have a small cfm 1.3 cubic foot insert, and after reading all the positive comment form the forum, I decided to install some insulation that I purchased at my local wood stove shop. At this stove shop they do a soft (insulation only) block off. The sales guy thought what a great idea to install a sheet metal plate, but had never heard of this before?

I simply stuffed the damper with the insulation that I purchased at the stove shop and am really happy with the results. I have a middle of the house chimney, with a uninsulated 6 inch SS liner.

The results were amazing! The most over used word on TV.

The insert reaches higher temps, I think faster.
Seems to hold more heat in the brick of the fire place.
More heat in the house and not going up and out, just beacuse the liner is sealer at the top dont assume its air tight.
This forum has made burning wood alot more fun. Someday I will install a steel plate too and get into the big leagues of wood burning.

 

[jadm]

I agree with what others have already said here but have to add that with my install (also an insert) I couldn't add a block off plate at the bottom because bricks had to be taken out of the damper area so that the ss liner had a straight shot up the chimney. My block off plate had to be placed at the top of our chimney - not ideal but it works for us. (My chimney is interior and our climate is warmer than yours probably is.)

When you call to ask about insulated liner etc. you might check on how experienced the installer is if you can. My first install was botched and I didn't know it because I was new to all of this. ONly found our when I had a problem and someone from another company came out to check on things for me. My second install was done by my very experienced chimney sweep who is also a fireman of many years and who does not cut corners. A lot cheaper to get it right the first time. :-S

 

[bonedoc]

Does this mean insulation is actually stuffed around the 6" chimney liner for the entire length of the chimney?

About how much have others paid for this??


This install is gonna kill me....

 

[mellow]

I installed mine myself, so I can't comment on installers pricing.

Check out this video to see if it is something you can do on your own:

http://www.youtube.com/watch?v=RRauuzjI-H4

 

[DAKSY]

Hey, bonedoc...

Does this mean insulation is actually stuffed around the 6" chimney liner for the entire length of the chimney?

Absolutely not.
If you insulate around the top of the liner - under the cap plate & around the liner in the damper area, it's gonna create a standing column of "Dead Air" in your chimney...
This should work as well as insulating the entire length.

About how much have others paid for this??

About $600 for the liner (30') & insulation...Install is extra...

This install is gonna kill me....

No it's not! It's gonna WARM YA!

 

[savageactor7]

If your chimney along the outside of the house the insulated liner is a good idea. Block off plates allowed store heat to radiate out to your living space instead of going up the chimney. If you have any friends or neighbors with an insert they will help set you straight.

 

[bonedoc]

Just spoke to my installer who:

1. Does plan to install a metal block-off plate.

2. Does not insulate the liner in new chimney's unless it is damaged or full of creosote as it will cost "$300 extra and increase efficiency only minimally".

3. Does not put in a damper as the FPX 33 elite(Lopi Declaration, Avalon Perfect-fit) have a seperate air control on the stove that functions like a damper.

Should I INSIST on the full-length insulation and pay $300 extra or is the benefit really negligible with the block-off plate and a new chimney?

What about just insulation around the plate to keep heat around the stove?

 

[mellow]

I have spoken of my experience with a 25ft exterior chimney. What you do with that info is up to you.

 

[DAKSY]

Should I INSIST on the full-length insulation and pay $300 extra or is the benefit really negligible with the block-off plate and a new chimney?

No, IMHO...

What about just insulation around the plate to keep heat around the stove?

Well, I'd have them insulate TOP & BOTTOM around the liner.
We've been installing liners this way for longer than I 've worked here.
We're in a VERY cold area & this works very well for keeping heat IN & cold OUT
We get NO installation complaints from our customers, in fact, we get lots of praise...

 

[bonedoc]

Should I INSIST on the full-length insulation and pay $300 extra or is the benefit really negligible with the block-off plate and a new chimney?

No, IMHO...

What about just insulation around the plate to keep heat around the stove?

Well, I'd have them insulate TOP & BOTTOM around the liner.
We've been installing liners this way for longer than I 've worked here.
We're in a VERY cold area & this works very well for keeping heat IN & cold OUT
We get NO installation complaints from our customers, in fact, we get lots of praise...

Thanks for you help, but....I'm a little confused.

My apologies...but are you saying NO, IMHO DON'T insist or NO, DO insist on the insulation full-length($300 extra).

 

[DAKSY]

My apologies...but are you saying NO, IMHO DON'T insist or NO, DO insist on the insulation full-length($300 extra)

My bad...DON'T insist on the full insulation...

 

[edthedawg]

I'm inclined to agree w/ DAKSY's experience in this regard - overall it sounds like you would be OK either way. If you wanted to insist on it, your installer has no problem doing it. If you don't want to spend the $300, just make sure it's packed well @ top and bottom and you'll likely not notice the difference... For the insert, I really like the idea of plentiful insulation packed in above the blockoff plate. Too many stories lately of "poor performing" inserts...

and because I'm curious... what do you have for wood lined up?

 

[bonedoc]

Thanks everyone.

That was a big help. I will probably pass on the full length insulation and make sure they insulate around the block of plate.

Is there a special type of insulation for this?

I have about 2 cords of Oak and Maple about 2 years seasoned....Just dying to be burned EFFICIENTLY for a change!!

 

[DAKSY]

You can use unfaced fiberglass insulation - WITHOUT PAPER - or
you can look for some rockwool or Kaowool...
Most people have fiberglass leftover from other projects,
& it can be used safely, as long as the paper's removed

 

[oconnor]

As far as installing your liner, let me ask one question - does your chimney meet code as it sits now?

To do that, you need 2 inches of airspace clearance all the way around it, with no combustibles inside that space. You have this on three sides, how is the forth?

If you do not, then your instructions for the liner will likely say that you require insulation to meet the specifics of the UL1777 listing that the liner is tested to.

If you don't follow the instructions that come with the liner, you can't meet code, (code rewuires following them) and you could have an insurability issue. Not as likely, as most inspectors/installer and insurers are quite unaware of the issue these days, but who knows when they will awaken to what code and instructions require.

As well, not insulating when you don't have the clearances to combustibles increases risk - you wouldn't do it around the stove itself, or around the smoke pipe, so don't do it around the liner.

As far as insulation goes, fiberglass and rockwool aren't spec'd or approved for use around a chimney (1200*F constant temp with 2100*F for up to an hour in a chimney fire), but KAOWOOL is (generically called ceramic wool blanket), so I'd stick to the stuff that is tested and sold for use around your liner. Lots of folks do lots of things that go well for them like rockwool/mineral wool and fiberglass, but with all respect to them, I prefer to recommend using approved techniques. Then, someone smarter than me has thought thru the scenarios that may not happen to an experienced user, but that if they did happen, could have adverse effects on a user that may have an overheat or chimney fire.

In my research so far, I haven't seen any manufacturer recommend mineral wool/rock wool or unfaced fiberglass around a liner. If it would pass testing, I'm sure some manufacturer would use it, as it is cheaper than the current approved alternatives.