Vermont Casting WinterWarm Fireplace Insert or System Flush with the Floor or Laid Over It?

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:

(K factor
of alternate		(Thickness of		(Required thickness
material)
	X	Wonderboard	=
				of alternate material)
(K factor of		required)
Wonderboard)

Let’s use brick as an example, since it is a commonly used hearth material. Its K factor is 5.0.

(5.0)	X (7/16” [11 mm]) = 2.6” (65 mm)
(0.84)

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.

WinterWarm Fireplace Insert or System

Over-laid Floor	Ventilated
Protector
	Plinth
24ga. Galva-
	Spark
nized Sheet
	Protector
Metal
	Strip
	Cabinet
Finished	Base
Floor
Sub-floor
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.

Inlaid Floor	Ventilated
Protector
	Plinth
24ga. Galva-
nized Sheet	Spark
Metal	Protector
	Strip
Finished	Cabinet
Floor
	Base
Sub-floor	FP1110
Plywood Shim

Fig. 33 The components of a flush hearth. The floor protector is inlaid flush with the finished floor.

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.

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