Chase Area Minimum; Recessed Ledge Detail - ORTAL 40 Series Installation And Operation Manual

Chase Area Minimum

To ensure the convective heat within the chase passively moves to the heat release at an optimal rate, all parts of the interior of the
chase must at least the same size as the fireplace heat release (see "Heat Release" section to determine your model's required heat
release size) at size at any given point. To determine if your chase meets this requirement, use the following equation at the narrowest
part of the chase.
Chase Area = (Chase Length x Chase Depth) – (Area of the Pipe)
Area of the Pipe:
4"x6" venting = 28.27 in
2
5"x8" venting = 50.27 in 2
3"x5" venting* = 19.63 in
*Used for Power Venting only
If the heat release is split into 25/75 portions due to an oversized ledge, the
chase only needs to be the size of 75% of the heat release because 25% of the
heat is already being released at the ledge (see "Ledge Detail" section below
for details).

Recessed Ledge Detail

A ledge over the top of a fireplace that is less than 24 inches (48 inches for Traditional series) from the top of the fireplace
viewing area must maintain a minimum of 12 inches from the top of the viewing area to the bottom of the building material.
Entire structure must be non-combustible (framing and finish).
If ledge surface area exceeds the values shown in the chart below, the heat release must be divided between the ledge and
the chase ceiling: 25% at the ledge and 75% at the chase ceiling. This is referred to as an oversized ledge (see diagram below).
Fireplace Series
75*
90-130**
150-170
200
250
*Includes 75x65 Curve/Curve TN
**Includes Island
Oversized Ledge
Oversized Recessed Ledge Detail
2
Maximum Ledge
Surface Area
A x B ≤ 220 sq. in.
A x B ≤ 340 sq. in.
A x B ≤ 410 sq. in.
A x B ≤ 520 sq. in.
A x B ≤ 580 sq. in.
Fireplace Chase (Top View)
A = ledge depth, B= ledge width (Top View)
NOTES:
Chase area minimum requirements must

be met throughout the entire fireplace
chase. See "Chase Area Minimum"
section above for details.
A Space Creator is shown in the diagrams

in this section for illustration purposes
only. These requirements apply to all
models in this installation manual.
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