Hearth and Home Technologies BIR50 operating instructions Using Offsets and Returns, Offset Chart

North Star

EPA Certified Fireplace

1.Using Offsets and Returns

a.To bypass any overhead obstructions, the chimney may be offset using a 15° or a 30° offset/return. Perform the following steps to determine the correct chimney component combination for your particular installation.

b.An offset and return may be attached together or a chimney section(s) may be used between an offset and return.

1)Measure how far the chimney needs to be shifted to enable it to avoid the overhead obstacle. See Figure 11A, dimension “A” to determine chimney sections required to achieve the needed shift.

2)After determining the offset dimension, refer to Table 1 and find the “A” dimension closest to but not less than the distance of shift needed for your installation.

3)The “B” dimension that coincides with the “A” dimension represents the required vertical clearance that is needed to complete the offset and return.

4)Read across the chart and find the number of chimney sections required and the model number of those particular chimney parts.

5)Whenever the chimney penetrates a floor/ceiling, a firestop spacer must be installed.

6)The effective height of the fireplace assembly is measured from the base of fireplace to top of starter collar.

WARNING!

Do not combine offsets to create an offset greater than 30° from vertical.This may create a fire hazard since the natural draft may be restricted.

Table 1				Offset Chart*
		15°		30°	SL306	SL312	SL318	SL324	SL336	SL348
	A	B	A	B
	1-5/8”	13-3/8”	3-7/8”	14-1/2”	-	-	-	-	-	--
	2-7/8”	17-3/4”	6-1/4”	18-5/8”	1	-	-	-	-	--
	-	-	8-5/8”	22-3/4”	2	-	-	-	-	--
	4-1/2”	23-5/8”	9-1/4”	23-3/4”	-	1	-	-	-	--
	-	-	11-5/8”	27-7/8”	1	1	-	-	-	--
	6”	29-3/8”	12-1/4”	29”	-	-	1	-	-	--
	7-1/4”	34”	14-5/8”	33”	-	2	-	-	-	--
	-	-	15-1/4”	34-1/8”	-	-	2	1	-	--
	-	-	17-5/8”	38-1/4”	1	-	-	1	-	-
	-	-	20-5/8”	43-1/2”	-	-	-	-	-	--
	10-5/8”	46-3/4”	21-1/4”	44-5/8”	-	-	-	-	1	-
	11-7/8”	51-3/8”	23-5/8”	48-3/8”	1	-	-	-	1	-
	-	-	26-5/8”	53-7/8”	-	-	-	2	-	-
	13-3/4”	58-3/8”	27-1/4”	55-3/4”	-	-	-	-	-	-
	15”	63”	29-5/8”	59”	1	-	-	-	-	1
	16-1/2”	68-3/4”	32-5/8”	64-1/4”	-	1	-	-	-	1
	18”	74-5/8”	35-5/8”	69-1/2”	-	-	1	-	-	1
	-	-	38-5/8”	74-5/8”	-	-	-	1	-	1
	-	-	41”	78-3/4”	1	-	-	1	-	1
	22-3/4”	91-7/8”	44-5/8”	85”	-	-	-	-	1	1
	24”	96-1/2”	47”	89-1/8”	1	-	-	-	1	1
	25”	103-1/2”	50-5/8”	95-1/2”	-	-	-	-	-	2

A

B

1-1/4" OVERLAP

Figure 11A - Chimney Offset/

Return

Example: Your “A” dimension from Figure 11A is 14-1/2”. Using Table 1 the dimension closest to, but not less than 14-1/2” is 14-5//8” using a 30° offset/return. It is then deter- mined from the table that you would need 33” (Dimension “B”) between the offset and return. The chimney com- ponents that best fit your application are two SL312s.

*Proper assembly of air cooled chimney parts result in an overlap at chimney joints of 1-1/4”. Effective length is built into this chart.

4-03 11 480-1081