Post in 'The Hearth Room - Wood Stoves and Fireplaces' started by woodsie8, May 9, 2008.
Does a liner ever fail?
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Since it's not a topic you'll read much about on here I'd say no. The only time I'd ever replace a liner is if you had a bad chimney fire. Otherwise it will more than likely outlast the stove/insert.
Yes. But not often. Most liners will outlast the stove/insert. But we had to replace one just this week. It was good heavy duty 304 SS but corroded near the bottom - above the stove collar in the area above the smoke shelf. The chimney top had been leaking badly and no one was maintaining the system. We were called in too late. The liner was in there about 15 years.
If you keep your chimney and liner maintained properly the SS liner should last over 25 years. Many will go much longer. But they must be inspected periodically for corrosion. In this case we just had, we probably could have saved most of the liner if it had been caught earlier by splicing in a repair and repairing the chimney crown/cap. In short, do the maintenance and the liner will last. Keep it clean and dry.
Very possible when used with oil. Also in some very corrosive and humid environments....near the ocean, in and old chimney with lots of moisture and dust, etc.
But, in general, a properly installed liner with wood burning should last a while.
We have even replaced Metal Insulated chimneys, so anything is possible.
Ok, sweeping/cleaning is one (the main?) maintenance item. Linking this to advice I got on installing a 6" liner in an existing masonry fireplace that has a damper "throat" that is aproximately 5.75 inches by 28 inches. Some said just distort the liner to squeeze it through the 5.75" dimension. So, if one does that how well does a 6" round chimney brush work at getting through and cleaning the liner that is "crushed' a bit where it passes through the damper?
Since the liner is hidden away, in the chimney .......... then how the heck do I know if it is leaking and or corroding? When I clean it, will it be apparent and will that be too late? I know that one installer told me that the liners expand and contract so they need to leave a space at the top for that to happen, when I asked about how they sealed the top plate. One said there was vents on the top plate to let the heat escape. I thought I wanted the heat in the chimney to keep the liner hot so less creosote.
Hum, I think it is common practice to wrap or otherwise insulate the liner to help keep it hot when it is in an exterior chimney, as most are. If the chimney is internal to the house the insulation isn't needed, and that saves $$$. In any case, we need to keep the chimney hot even when the fire is low if we're to minimize creosote. I have never heard anything about putting vents in the top plate, sounds wrong to me.
First, "squeezing" the liner to fit through the damper is a bad idea. It will affect performance, and as you already guessed, it will make cleaning with a standard brush impossible. Special "Oval" pipes and adapters are made for this purpose. Another way to handle this is to cut or remove the damper frame (which, of course, damages the fireplace. But it can be repaired later if necessary). If using an Oval pipe section you will need at least two different brushes, an oval one and a round one.
Kim, this is the job of a chimney sweep. For lack of a chimney sweep you will get out your tools and gloves and remove the insert, the block off plate, and then visually inspect the liner. Us chimney sweeps have secrets that make this job a little easier. If you are really curious you can sign up for classes at CSIA.ORG and become a chimney sweep. We sure do need more qualified sweeps!
The guy who said the liner expands and contracts is right on point. The other guy who said there are vents for heat to escape is misinformed.
Fact is, you cannot control every bit of heat loss in your chimney. The re-line is not a sealed system and it cannot be a sealed system without causing more problems than it solves. If you were able to get a custom engineered sealed liner system for your house you would pay considerably more than the prices currently in play (and such system are possible but not generally available in the marketplace due to market factors). The system will shed water and allow the liner to expand and contract. It will not be sealed air tight. And trying to keep all the heat in the chimney is not practical or necessary. Let it go (he said, gently). You'll get plenty of heat from the stove and the stainless steel liner will draft plenty. Creosote will not be a problem. (If you do have creosote problems it will not be the fault of your liner).
I'm not to sure that a wrap around the liner is very common.When i went shopping for a wood stove i went to 3 places in my area and not one included a wrap in the estimate.It did not even come up in conversation.PS!they all knew i had a external chimney.
Well this may be worth a new thread, find out what the majority view is. This thread is the first place discussing chimney liners that the subject of no insulation has come up. Not putting on insulation will cut cost several hundred dollars for a two story chimney, in NJ its almost $1K, and that's a wrap, not a pour in mix.
For a 31' chimney I get labor at about $700 and chimney/insulation/top/connector at about $1,300. What numbers are you seeing without insulation? One of us may be getting bad advice. I can look up a thread I started a few weeks back asking about insulation, short of that, I can say none of the many responses suggested go without insulation.
Was this inspected? I'm wondering if they were just trying to come in with the lowest bid? How many places were asked for the best job possible?
Airspace clearances between the masonry chimney exterior and combustible
materials should be checked to verify whether the chimney is in
accordance with the clearance specifications contained in:
1. NFPA 211
2. Other recognized major building codes
3. These instructions
NFPA 211 states that the minimum airspace clearance between exterior
masonry chimneys (which have the chimney completely outside the exterior
wall of the building, excluding the soffit or cornice area) and combustible
material shall be at least 1”.
Wood And Coal Applications
There are three scenarios you may encounter when lining for wood and
coal that will affect your choice of insulation options.
In a case where a masonry chimney is found to have at least 1” clearance
to combustibles the minimum insulation requirements are one wrap of 1⁄4”
foil-face insulation or 1” of HomeSaver InsulationMix or TherMix insulation.
When less than 1” clearance exists between the exterior of the masonry and
the surrounding combustibles, the minimum insulation requirements are
one wrap of 1⁄2” foil-face insulation, two wraps of 1⁄4” foil-face insulation, or
1” of HomeSaver InsulationMix or TherMix insulation.
Another option is to just wrap the top couple feet or so under the cap. This will keep a warm dead air space inside the chimney and cost much less than a full liner wrap.
We've been through this one a number of times, but the short and sweet is that the insulation is specified in certain instructions NOT because the chimney get's too cool or causes creosote, but rather because in these cases it is assumed that the chimney itself is too close to certain combustible or not lined at all (with terra cotta), and therefore this is what is required to bring the chimney up to snuff.
Not to say that insulation does not help in a lot of cases - it does.....in my opinion, the further north you are, the most case there is for insulation, especially on outside chimneys. Interior chimney are often older, unlined and don't have clearance to combustibles, so they are also candidates!
I do think that the majority of Fireplace shops will not quote insulation as a default, probably because of a number of reasons. The customer usually makes it clear that they are price-sensitive. We used to have people choke when they heard a chimney had to be lined at all...they just didn't assume it had to be!
Another factor is that shops tend to get stuck doing things a certain way....with the attitude of "it's worked up til now", as opposed to changing instantly when every new NFPA comes out. Remember that the stove manuals and listings usually differ greatly from NFPA in numerous ways. As an example, a modern insert may show a Direct Connect (5 feet up) in the manual as an allowed installation. So both the customer and dealer think (and are probably correct) that a full liner is steps above the "minimum".
Safety and longevity are always a matter of degree. I would say that a poured in place (bladder type) liner done right (with flue tiles busted out) is one of the best options out there, but I doubt many stores or sweeps suggest this either.
Now onto a bit of opinion and physics......it is REALLY hard for me to imagine any scenario where a flue tile lined chimney with 4" plus of masonry around it....even one a bit short in the CURRENT NFPA clearances (these have changed over the years).....with a 6" liner randomly dropped down it, could overheat that wood. Again, this is pure speculation, but with a round pipe - which only can touch the liner in a small area - that type of heat transfer seems impossible. I would like to speak with a technician at the labs sometime and see how the liner tests are conducted. I cannot imagine that they test various sized liners in various size chimneys. It would be educational to find out.
My speculation comes from the old books by Jay Shelton, where he showed that even stove clearances were pretty arbitrary, because physics would say that a round stove or one with a smaller side could be closer to a wall than a large plate. Back then, all stoves were 36". I suspect we see the same with liner - that it is not in the interest of the lab or maker to test various sizes in different flues, so the codes are "one size fits all".
Well, not sure where this leaves me, but it seem that I may not need the expense of insulation. I have a 1985 built fireplace wall that is free standing and is outside the exterior frame wall of the house. The 11x11 tile liner has, of course, vented without the benefit of any liner many fires in the fireplace and in an old-fashioned insert that just dumped into the fireplace smoke chamber, no up pipe at all. The tile line is surrounded by a brick exterior and interior, that faces the inside of the house. As for clearance to combustibles, I'd say there is a minimum of 6" of brick. So, if the insulation doesn't improve the performance: creosote management and/or draft, why must I spend the money for an insulation wrap? One bid I have specifically quotes $450 for insulation, or about 10% of the total cost of equipment plus installation. Seems like a real savings to not get insulation.
I can say my experience with tho old insert, I used it for 15 years, it managed to put a lot of heat into the house without the benefit of even a liner, never mind any insulation other than the masonry materials.
It comes down to this: If your masonry fireplace/chimney meets current codes the insulation is an OPTION. If it cannot be confirmed by visual inspection that your chimney passes the current codes the insulation is REQUIRED.
In my opinion, insulation should always be used when the masonry mass is exposed to the outside temperatures, even if it is not required. $400-$500 over the life of the appliance and liner system (20 years) is a small amount to pay for increased performance and easier maintenance. But, if you don't have the cash, and it's not required, you can skip it.
Thanks, that's helpful input.
It is unlikely I will live in this house for more than another 5 years, so pay back on the insulation isn't likely, but better efficiency is still a plus. This will not be a selling issue, or will it, given the price of oil an efficient insert may add at least the going cost of one in the selling price (faster sale at least). I have one price insulation for a 31' liner of $450, overall installation a separate item of $625. Another estimate is $346.25 for an insulation kit (must be right out of the "book" to include the 25 cents) and overall installation of $750. When the cost of the liner and connecting parts top and bottom are added one bid is: $2,000 and the other is $2025. They must be using the same play book with a different allocation of prices/costs. So the installation cost is not the determining factor, of course I don't have details on the materials other than flexible stainless steel liner (continuous or one piece), everything else is totally generic, e.g., Insulation, connector, collar plate, cap...
Well, in those cases where re-selling of the house is concerned it is always a tough call. First, the wood stove/insert may not help the re-sale cause at all. It's a crap shoot. Some people love the idea, some people hate it. But, assuming you sell to a person who loves wood stoves, I would suggest that investing in the insulation makes good sense. You can confidently say you did not skimp on the materials and installed it in the best way as suggested by the professionals.
For what it's worth, I would have asked for quite a bit more than what you are listing here. But I take the time to carefully explain the different possibilities and I ask my customers to pay a price commensurate with my professionalism. Many in my market are wiling to pay higher prices for a more detailed and valuable service than is offered through other sources. I do not appeal to those who only care about the lowest price. The trick is showing that we are worth the extra money. So, I disclose everything - how much it costs me to hire honest and responsible helpers, the exact materials we use, and why, and we offer to install alternate materials that cost less if the client asks us, as long as they agree that the less costly materials offer less value and higher risk.
If I were you, I would ask your dealer to show you the materials he/she is proposing to install and tell you why they feel they are the best choice for your situation. If you are satisfied that they are giving you good value you should pay their price.
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