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Prefab Chimney System
Characteristics
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Prefab chimney systems cannot be used the same
way as a masonry chimney system. What’s difficult about this is that the average
person doesn’t even know if they have a prefab or a masonry fireplace.
There are important issues that you as a homeowner need to know about
prefab systems:
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The firebox, where you make the fire, is built out of steel and
typically has four walls (two sides, a back, and a floor) of what we
call refractory panels inside the box. These panels are cast in molds
out of a refractory cement and stamped to look like bricks. Their
purpose is to reduce the heat to the firebox. In older systems, the
sidewalls and and/or backwall may be metal panels instead of the
refractory material.
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These refractory panels can easily crack and are extremely expensive to
replace. Cracks in the panels can also cause a potentially dangerous
situation since they have lost their insulating ability and may transfer
heat to combustible materials. Most of the fireplace manufacturers
recommend replacing a panel if you can fit the edge of a nickel inside the
crack. The main cause
for cracks developing is having too big or too hot of a fire. We highly
recommend that you should limit the size of your fires to either ONE
prefabricated log (i.e. Duraflame or Pine Mountain), or just 2 to 3
small pieces of wood at a time. Having large fires will guarantee that
you will prematurely crack the fragile panels.
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Unlike a masonry chimney, a prefab
chimney system carries a UL Listing, and is actually considered an
appliance. Prefabs cannot be modified in any way or it will void out the
UL Listing, and void the warranty. This means the homeowner can not go
back to the manufacturer for any liability should a problem arise.
Therefore it is essential for a homeowner to hire a professional who
"knows the rules" about prefab fireplace systems.
Please click on the
Prefab Refractory Wall Replacement
page to view pictures showing the replacement of the refractory panels
in a prefab fireplace. |
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In order to know what parts go with
your system, we first need to know the manufacturer and the model
number. A metal tag (generally about half the size of a credit card) can
be found either on the front of the firebox by the fire screen or inside
above one of the side panels with the necessary information. Once
we know the manufacturer and the model number, we can then contact the
manufacturer or distributor to get the exact part that matches your
system. Note: This
information can also be found in the owner's manual.
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information that we need from this tag is the name of the manufacturer,
the model number, and many times the manufacture date.
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are some chimney sweeps who will install the generic "universal
refractories". These are made by outside companies and are cut by the
installer to fit as replacement panels. While these universal
refractories can be less costly, this goes against the manufacturer’s
specifications and voids out the listing on the system. |
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One of the major repercussions of
this would be in the case of a house fire caused by something inside the
fireplace. If the insurance company were to determine that the system
had been modified against the manufacturer’s specifications, whether or
not this was the cause of the fire, it may mean that the insurance
wouldn’t pay the claim and you as the homeowner would be on the hook to
pay for the damage. For this reason, to protect you as the consumer, we
do NOT install universal refractories, and ONLY install manufacturer’s
specific parts!
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On
most prefab systems, there is a flat metal cover at the top that the
chimney cap attaches to called the chase cover. Sometimes rain can leak
inside the chase cover, and one sign for that would be if you hear water
dripping on metal inside the wall by the fireplace during or after it
rains. This must be addressed immediately so that the chase cover can be
replaced. If you wait too long, the water will rust out the system and
you’ll need to replace the entire system.
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Examples
of Potential Prefab Problems... |
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Replacing a chimney cap with a non-factory unlisted cap. The flue
pipe in a prefab system generally consists of an inner pipe, an air
space and an outer pipe. The air space in between the pipes is there to
cool the system, and the wrong cap can inhibit this cooling and allow
the system to overheat which could lead to a potential fire hazard. |
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2) Installing glass doors on a
prefab system that was not designed specifically for that fireplace
model could potentially overheat the system since the doors may
cover up the air vents inside the firebox that will normally draw in
cool air from the room. |
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Using a non-factory shroud or decorative surround around the
chimney cap at the top may restrict the chimney system’s ability to
vent properly.
In many cases these
modifications can even make it impossible to clean the top area of the
chimney when sweeping or be able to perform any kind of visual
inspection from the top.
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4) How a prefab system is
maintained can make a huge difference in how long the system will last
as well as how safe it is when used.
Rust can be a major problem
since the metal becomes thin and weak, and can even rust through.
Of course this problem seems to most often occur in areas of the system
that see the highest heat such as around the damper area, in the flue
pipe and chimney cap.
If damage exists such as what
is shown here, the system should no longer be used and replacement is
recommended.
We also see a lot of rust in
systems in parts of the county close to the ocean. This may
prematurely require replacing the entire system.
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5) Remember that you can be part of
the solution in maintaining your prefab chimney system. If
something looks a little strange, it would be strongly recommended to
have your chimney system checked out by a CSIA Certified Chimney
Professional to avoid any problems.
The pictures on the right show
systems without adequate noncombustible clearances. The top picture
shows no hearth area in front of the fireplace. It is also not
recommended to have your television mounted above the fireplace opening.
(Some electronics manufacturers may void out warranties if TV's are
located above the fireplace.)
The lower right picture shows the
wooden mantle pillars being dangerously close to the fireplace opening.
The examples below show systems
that were not installed properly. They can have smoking problems
as well as be a major fire hazard. |
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Most prefab systems only have a
life span of about 15-30 years (partly depending on how close it is to the
coast), whereas masonry chimneys built today could last upwards to one
hundred years or more. Many of the prefab systems that are in homes built in
the 1970's here in San Diego, CA are getting to the end of their life span.
This makes it that much more critical to have your system maintained by a
CSIA Certified Chimney Sweep to avoid as much risk as possible of a costly
fire.
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Click here to return to
Prefab Chimneys Main Page.
Click
here to go to the
Prefab Refractory Wall Replacement Page.
Click
here
to return to
Swede Chimney
Sweep Home Page. |