25
WinterWarm Fireplace Insert or System
2000941
Custom-made floor protectors may be used if they offer
the same protection as the approved floor protector
described in the preceding paragraph, which in testing
was found to have a standard K value of 0.84. Custom-
built floor protectors must have a K value equal to, or
less than, 0.84, meaning that heat will transfer at the
same rate or more slowly than the tested standard.
To calculate the thickness required for an alternate ma-
terial to result in a K value of 0.84, first determine the
alternate material’s K factor. This information should be
available from your local building supply yard. Then,
calculate the following formula:
Let’s use brick as an example, since it is a commonly
used hearth material. Its K factor is 5.0.
That is, when using brick for the hearth extension, the
brick must be a minimum of 2.6” (65 mm) thick.
Once you know the K factor of a given material, you
can use this same formula to calculate its required
thickness for approved hearth protection.
Flush with the Floor or Laid Over It?
Generally, it is easier to lay floor protectors over the fin-
ished floor in existing homes. In new construction, flush
installations are a popular alternative.
When placed over a finished floor, the floor protector
extends completely under the ventilated plinth. (Fig.
32) The cabinet is elevated by an amount equal to the
thickness of the floor protector so that the plinth and
cabinet are at the same level. This is necessary for a
proper fit between the WinterWarm front and the plinth.
If you raise the cabinet more than 1” (25 mm), a corre-
sponding increase in the height of the framed chase is
required to retain adequate clearance.
When the floor protector is installed flush, the Winter-
Warm cabinet rests on plywood shimming that brings it
level with the finished floor. (Fig. 33)
Whichever method you choose, the floor protector must
satisfy the requirements outlined above, and the 3” x
38” (76 x 965 mm) sheet metal spark protector strip
(included) must be laid under the junction of the cabinet
and the ventilated plinth.
Important Reminders:
1.
INSTALL ONLY AS ILLUSTRATED.
2. Elevating the cabinet requires a corresponding in-
crease in the height of the chase to retain adequate
clearances. Refer to the chase specifications on
Page 20 and double-check that all clearances will be
satisfied.
3. The air inlet through the ventilated plinth must not be
blocked.
4. A 3” x 38” (76 mm x 965 mm) strip of sheet metal
(included in your Fireplace System) must be placed
as a spark protector painted-side up underneath the
joint between the front of the cabinet and the venti-
lated plinth.
FP1109
WinterWarm
raised hearth
4/05/01 djt
Over-laid Floor
Protector
24ga. Galva-
nized Sheet
Metal
Finished
Floor
Sub-floor
Ventilated
Plinth
Spark
Protector
Strip
Cabinet
Base
Plywood Shim
FP1109
Fig. 32
The components of a raised hearth. The floor protec-
tor is placed over the finished floor and extends completely
under the ventilated plinth.
FP1110
WinterWarm
Flush hearth
4/05/01 djt
Inlaid Floor
Protector
24ga. Galva-
nized Sheet
Metal
Finished
Floor
Sub-floor
Ventilated
Plinth
Spark
Protector
Strip
Cabinet
Base
Plywood Shim
FP1110
Fig. 33
The components of a flush hearth. The floor protector
is inlaid flush with the finished floor.
(K factor
of alternate
material)
(K factor of
Wonderboard)
(Thickness of
Wonderboard
required)
(Required thickness
of alternate material)
X
=
(5.0)
(0.84)
X (7/16” [11 mm]) = 2.6” (65 mm)
