Specifications

14 63D4004

INSERT AND PIPE INSTALLATIONS

NOTES ON CHIMNEY AND INSERT PIPE INSTALLATIONS:

Maintaining a clean chimney is important. Chimneys should be inspected regularly for creosote buildup. A straight

chimney is easier to clean than one with 45 or 90 degree bends. A bend requires the pipe to be removed for cleaning. The

insert bafﬂ e must be removed when cleaning the chimney. Chimney sweepings will build up on top of bafﬂ e causing a

blocked ﬂ ue and/or a ﬁ re hazard.

Steel Chimney

Most factory made “Class A” steel chimneys have a layer of insulation around the inner ﬂ ue. This insulation keeps the

smoke warm and protects the surrounding structure from the high ﬂ ue temperatures. Because the insulation is less dense

than masonry, the inner steel liner warms up more quickly than masonry chimney; this makes the steel chimney support a

good draft more quickly than masonry does.

Indoor/Outdoor Location

Because the chimney’s function is to keep the smoke warm, it is best to locate it inside the house. This location uses the

house as insulation for the ﬂ ue and allows some radiant heat release form the ﬂ ue into the home. Since an interior chimney

doesn’t continuously lose its heat to the outdoors, less heat from the insert is required to get it warm and keep it warm.

Flue Sizing

The ﬂ ue size for a controlled-combustion appliance should be based on the cross-sectional volume of the insert ﬂ ue outlet.

In this case, more is deﬁ nitely not better. Hot gases lose heat through expansion; if a insert with a six-inch ﬂ ue collar (28

square inch area) is vented into a 10" x 10" ﬂ ue, the gases will expand to over three times their original volume. As gases

cool with expansion, draft strength decreases. If the oversized ﬂ ue is also outside the house, the heat it absorbs will be

conducted to the outdoor air and the ﬂ ue will remain relatively cool.

It is common for a masonry ﬂ ue to be oversized for the insert. Such a chimney can take quite a while to warm up, and

the insert performance will likely be disappointing. The best solution to an oversize ﬂ ue problem is the installation of an

insulated steel chimney liner of the same diameter as the appliance ﬂ ue outlet. The liner keeps the exhaust gas warm and

the result is a stronger draft. An uninsulated liner is a second choice—although the liner will keep the exhaust restricted to

its original volume, the air around the liner will require time and heat energy to warm up.

Check your local codes. You may be required to install a ﬂ ue liner in any oversize masonry ﬂ ue.

Masonry Chimney

Although masonry is the traditional material used for chimney construction, it can have distinct performance

disadvantages when used to vent a controlled combustion wood insert. Masonry forms an effective “heat sink”—that is, it

absorbs and holds heat for long periods of time.

The large mass however, may take a long time to become hot enough to sustain a strong draft. The larger the chimney (in

total mass) the longer it will take to warm up. Cold masonry will actually cool exhaust gases enough to diminish draft

strength. This problem is worse if the chimney is located outside the home or if the chimney ﬂ ue has a cross-sectional

volume much larger than the insert outlet.

Single Venting

Your insert requires a dedicated ﬂ ue. Do not connect the insert to a ﬂ ue used by any other appliance. Chimney draft is a

natural form of energy and follows the path of least resistance. If the insert is vented to a ﬂ ue that also serves open replace

or another appliance, the draft will also pull air through those avenues.

The additional airﬂ ow will lower the ﬂ ue temperatures, reduce draft strength and promote creosote development; overall

insert performance will suffer. The effect is similar to that of a vacuum cleaner with a hole in the hose. In some extreme

instances, the other appliances can even impose a negative draft and result in a dangerous draft reversal.