cast in-place vs steel liner: old farmhouse

[vap0rtranz]

What's the rational for adding a steel liner to a cast in-place one?

We're moving to an old farmhouse, so I had our chimney folks do an inspection of the brick chimney stack. They "recommend" a steel liner be _added_ to the cast in-place -- but they didn't find any issues with the chimney.

Are insurance companies pushing for steel? Are chimney guys pushing new liners just to get paid?

My chimney folks are highly recommended here and have every certification on the planet (CSIA, NCSG, HPBA, NFI). I'm just wondering what the rational is for this recommendation ... my chimney would have 2 liners despite no defects being found.

 

[SpaceBus]

Maybe the cast liner is 8+ inches and they are suggesting a six inch liner.

 

[EatenByLimestone]

Why not ask them? They are the only ones who will not be guessing why they recommended it at this point.

 

[vap0rtranz]

Their answer was:

"We do not do cast in place liners, nor do I know of anyone who does them anymore. Cast in place liners do not hold up well in WI with our harsh winters."

So I'm trying to justify the cost. Quote is $3,800 to install 6" stainless steel insulated liner ... seeing the price of the steel liners online, I'm assuming labor drove up the cost?

 

[MongoMongoson]

Where in Wisconsin? I recommend getting quotes from more than one installer. My second quote on a chimney installation was much more attractive than my first. Same thing happened with a friend of mine. His second quote was about 2/3 of the first.

Is this chimney external? That would be a good reason to install an insulated liner.

If they are adding an insulated 6" liner to the chimney that already has a cast in place liner, that implies that your chimney is oversized for the device you want to install.

What device are you planning to install?

 

[EatenByLimestone]

What is the roof pitch? How tall is the chimney, and how hard is it to get to the top of the chimney? Pics would help.

 

[coaly]

It depends on what appliance you're using the chimney flue for. (or open burning fireplace)
Is it venting a wood burning Insert?
If connecting an appliance such as an Insert or stove, what size is the appliance outlet, and what size is the existing flue?
The flue needs to be sized for the appliance.

It's doubtful in an older farmhouse that the chimney has the proper clearances to combustible framing materials unless the entire wall is brick or non-combustible. In that case it would require an insulated liner which you didn't mention.

 

[vap0rtranz]

Is this chimney external?

No, it's dead center of the house.

What is the roof pitch?

12 pitch, and metal. No installer will touch it until Spring, and even then my guess is the roof drove up the price.

How tall is the chimney

2 stories. I'll measure when back at the house but about 26' from stove pipe hole to cap.

Is it venting a wood burning Insert?

No, a woodstove. There's no fireplace. There's a T from the stove pipe hole to the chimney flue, then straight up to cap from there.

The flue needs to be sized for the appliance.

The cast in-place is 8" and my woodstove takes 6". I assume that's the big reason the installer wants to line the chimney.

In that case it would require an insulated liner which you didn't mention.

They're quoting insulated steel UL liner. Chimney cross section would be: brick + cast in-place + insulated steel liner after done.

When I look up kits for flex insulated, I'm getting around $1k. So this is $2800 in labor ...

 

[bholler]

No, it's dead center of the house.



12 pitch, and metal. No installer will touch it until Spring, and even then my guess is the roof drove up the price.



2 stories. I'll measure when back at the house but about 26' from stove pipe hole to cap.



No, a woodstove. There's no fireplace. There's a T from the stove pipe hole to the chimney flue, then straight up to cap from there.



The cast in-place is 8" and my woodstove takes 6". I assume that's the big reason the installer wants to line the chimney.



They're quoting insulated steel UL liner. Chimney cross section would be: brick + cast in-place + insulated steel liner after done.

When I look up kits for flex insulated, I'm getting around $1k. So this is $2800 in labor ...

My dealer cost on high quality liners and components is more than $1000. $3800 does sound a bit high but not crazy when you consider the access as well

 

[EatenByLimestone]

12/12 metal roof in the center of the house is going to raise the price. The installer might need a lift in order to get the liner up there and safely installed. It's not going to be light weight. Depending on the size needed, that can add a good bit to the cost.

 

[coaly]

The cast in-place is 8" and my woodstove takes 6". I assume that's the big reason the installer wants to line the chimney.

Yes, there are many reasons an insulated liner the correct size is needed, but we needed more information to know what they were looking at.
An insert would be an automatic liner required if it was installed in a fireplace using the existing flue. That's why I asked if it was an Insert or stove.

Some stove installation instructions specify the flue size required. If this is a UL Listed stove with that in the instructions, that is a legal reason for code compliance installing to manufacturers specs. The reason is tested appliances need to be installed "as tested" and the instructions become a part of the UL Listing.

Increasing from 6 to 8 allows the hot exhaust gasses to expand and cool. This 2 inch diameter increase cools them by almost 1/2. (the square inch area of 6 round (28.26) to 8 round (50.24) is almost double, 8 inch square is 64 square inches, more than double the 6 inch round) An example letting 500* exhaust gasses out of the stove (reading 250* on pipe surface thermometer) would drop to 250 expanding in the chimney, cooling even more as it rises. The object is keeping the flue gas temperature above 250* all the way to the top when smoke is present. This allows water vapor from combustion to condense in flue. Smoke particles then stick to flue walls forming creosote. Waste heat is needed up the chimney to prevent condensing. With a large stove, that is not a big problem, but cuts into efficiency. With a smaller stove, this uses so much heat up the stack you may not have enough to radiate into the area you're heating. So the square footage being heated and the stove size are contributing factors for a recommendation for safety preventing creosote, efficiency, or simply to make the stove heat the area you're heating. If you are heating the maximum area the stove is designed for, you need the most efficient chimney possible.