Lennox Hearth RDI-42-H, HCI-42-H FTF8 VERTICAL ELEVATION CHART, Offset Calculations

12

The offset and return elbows may be attached together, or a section or sections of chimney may be used between, but do not exceed 20' in total length between elbows. If sections of pipe exceed 10' between elbows, a chimney stabi- lizer must be used at the midpoint (Figure 36 ). The stabilizer support straps must be attached under tension (in shear) to structural framing members above. When two sets of elbows are used, the maximum combined length of chim- ney used between elbows cannot exceed 20' (Figure 37 ). Example: If C1 = 10' then C2 cannot exceed 10'.

If an offset exceeds 6' in length, each chimney joint beyond the first 6' of offset to the return elbow, must be secured by a No. 8 x 1/2" sheet metal screw located at the underside of the joint (Figure 38 ).

A 1/8" diameter hole must be drilled in the chimney joint using a 1/8" diameter drill. Hole should be drilled in center of joint overlap (Figure 39 ). Be sure to drill only through the outer chimney casting. Do not puncture the inner flue.

Maximum offset of chimney system is 30° . Two offsets must not be assembled to form a 60° offset. However, two sets of offset and return elbows may be used on a single flue system, provided the total height of the system exceeds 25'.

Return elbow support straps must be securely attached under tension (in shear) to structural framing members above. Do not substitute a FTF8-30 offset elbow in place of a FTF8-E30 return elbow.

OFFSET CALCULATIONS

Step 1. Use Offset Chart to determine amount of horizontal offset (A) and height (B) for vari- ous chimney section assemblies.

Step 2. Use “Height of Chimney Only” column in The Vertical Elevation Chart to determine combinations of chimney used above return elbow to achieve desired heights. Reference Components Effective Height Chart in vertical elevation chart section.

Step 3. Use Elevation Chart as job estimator only. Add necessary firestop spacers and sta- bilizers as required. Firestop spacers must be used as shown in Figures 22 and 23 and stabilizers as shown in Figure 28.

FTF8 VERTICAL ELEVATION CHART

	Height Of				Number Of FTF8					Height Of				Number Of FTF8
Chimney Only					Chimney Lengths					Chimney Only				Chimney Lengths
Inches		Feet/Inches			12"	18"	36"	48"	Inches		Feet/Inches			12"	18"	36"	48"
11		0	11		1	0	0	0	386	¹⁄₂	32	2	¹⁄₂	0	1	0	8
17		1	5		0	1	0	0	390	³⁄₄	32	6	³⁄₄	2	0	0	8
21	¹⁄₄	1	9	¹⁄₄	2	0	0	0	396	³⁄₄	33	0	³⁄₄	1	1	0	8
27	¹⁄₄	2	3	¹⁄₄	1	1	0	0	404	¹⁄₂	33	8	¹⁄₂	0	0	1	8
35		2	11		0	0	1	0	414	³⁄₄	34	6	³⁄₄	1	0	1	8
47		3	11		0	0	0	1	416	¹⁄₂	34	8	¹⁄₂	0	0	0	9
51	¹⁄₄	4	3	¹⁄₄	0	1	1	0	420	³⁄₄	35	0	³⁄₄	0	1	1	8
57	¹⁄₄	4	9	¹⁄₄	1	0	0	1	426	³⁄₄	35	6	³⁄₄	1	0	0	9
63	¹⁄₄	5	3	¹⁄₄	0	1	0	1	432	³⁄₄	36	0	³⁄₄	0	1	0	9
67	¹⁄₄	5	7	¹⁄₄	2	0	0	1	437		36	5		2	0	0	9
73	¹⁄₄	6	1	¹⁄₄	1	1	0	1	443		36	11		1	1	0	9
81	¹⁄₄	6	9	¹⁄₄	0	0	1	1	450	³⁄₄	37	6	³⁄₄	0	0	1	9
93	¹⁄₄	7	9	¹⁄₄	0	0	0	2	461		38	5		1	0	1	9
97	¹⁄₄	8	1	¹⁄₄	0	1	1	1	462	³⁄₄	38	6	³⁄₄	0	0	0	10
102	¹⁄₂	8	6	¹⁄₂	1	0	0	2	466	³⁄₄	38	10	³⁄₄	0	1	1	9
109	¹⁄₄	9	1	¹⁄₄	0	1	0	2	472		³⁄₄	39	4³⁄₄	1	0	0	10
113	¹⁄₂	9	5	¹⁄₂	2	0	0	2	478	³⁄₄	39	10	³⁄₄	0	1	0	10
119	¹⁄₂	9	11	¹⁄₂	1	1	0	2	483		40	3		2	0	0	10
127	¹⁄₄	10	7	¹⁄₄	0	0	1	2	489		40	9		1	1	0	10
137	¹⁄₂	11	5	¹⁄₂	1	0	1	2	496	³⁄₄	41	4	³⁄₄	0	0	1	10
139	¹⁄₄	11	7	¹⁄₄	0	0	0	3	507		42	3		1	0	1	10
143	¹⁄₂	11	11	¹⁄₂	0	1	1	2	508	³⁄₄	42	4	³⁄₄	0	0	0	11
149	¹⁄₂	12	5	¹⁄₂	1	0	0	3	513		42	9		0	1	1	10
155	¹⁄₂	12	11	¹⁄₂	0	1	0	3	519		43	3		1	0	0	11
159	³⁄₄	13	3	³⁄₄	2	0	0	3	525		43	9		0	1	0	11
165	³⁄₄	13	9	³⁄₄	1	1	0	3	529	¹⁄₄	44	1	¹⁄₄	2	0	0	11
173	¹⁄₂	14	5	¹⁄₂	0	0	1	3	535	¹⁄₄	44	7	¹⁄₄	1	1	0	11
183	³⁄₄	15	3	³⁄₄	1	0	1	3	543		45	3		0	0	1	11
185	¹⁄₂	15	5	¹⁄₂	0	0	0	4	553	¹⁄₄	46	1	¹⁄₄	1	0	1	11
189	³⁄₄	15	9	³⁄₄	0	1	1	3	555		46	3		0	0	0	12
195	³⁄₄	16	3	³⁄₄	1	0	0	4	559	¹⁄₄	46	7	¹⁄₄	0	1	1	11
201	³⁄₄	16	9	³⁄₄	0	1	0	4	565	¹⁄₄	47	1	¹⁄₄	1	0	0	12
206		17	2		2	0	0	4	571	¹⁄₄	47	5	¹⁄₄	0	1	0	12
212		17	8		1	1	0	4	575	¹⁄₂	47	11	¹⁄₂	2	0	0	12
219	³⁄₄	18	3	³⁄₄	0	0	1	4	581	¹⁄₂	48	5	¹⁄₂	1	1	0	12
230		19	2		1	0	1	4	589	¹⁄₄	49	1	¹⁄₄	0	0	1	12
231	³⁄₄	19	3	³⁄₄	0	0	0	5	599	¹⁄₂	49	11	¹⁄₂	1	0	1	12
236		19	8		0	1	1	4	601	¹⁄₄	50	1	¹⁄₄	0	0	0	13
242		20	2		1	0	0	5	605	¹⁄₂	50	5	¹⁄₂	0	1	1	12
248		20	8		0	1	0	5	611	¹⁄₂	51	11	¹⁄₂	1	0	0	13
252		21	0		2	0	0	5	617	¹⁄₂	51	5	¹⁄₂	0	1	0	13
258		21	6		1	1	0	5	621	¹⁄₂	51	9	¹⁄₂	2	0	0	13
266		22	2		0	0	1	5	627	¹⁄₂	52	3	¹⁄₂	1	1	0	13
276		23	0		1	0	1	5	635	¹⁄₂	52	11	¹⁄₂	0	0	1	13
278		23	2		0	0	0	6	645	¹⁄₂	53	9	¹⁄₂	1	0	1	13
282		23	6		0	1	1	5	647	¹⁄₂	53	11	¹⁄₂	0	0	0	14
288		24	0		1	0	0	6	651	¹⁄₂	54	3	¹⁄₂	0	1	1	13
294	³⁄₄	24	6	³⁄₄	0	1	0	6	657	¹⁄₂	54	9	¹⁄₂	1	0	0	14
298	¹⁄₄	24	10	¹⁄₄	2	0	0	6	663	¹⁄₂	55	3	¹⁄₂	0	1	0	14
304	¹⁄₄	25	4	¹⁄₄	1	1	0	6	667	³⁄₄	55	7	³⁄₄	2	0	0	14
312		26	0		0	0	1	6	673	³⁄₄	56	1	³⁄₄	1	1	0	14
322	¹⁄₄	26	10	¹⁄₄	1	0	1	6	681	¹⁄₂	56	9	¹⁄₂	0	0	1	14
324		27	0		0	0	0	7	691	³⁄₄	57	7	³⁄₄	1	0	1	14
328	¹⁄₄	27	4	¹⁄₄	0	1	1	6	693	¹⁄₂	57	9	¹⁄₂	0	0	0	15
334	¹⁄₄	27	10	¹⁄₄	1	0	0	7	697	³⁄₄	58	1	³⁄₄	0	1	1	14
340	¹⁄₄	28	4	¹⁄₄	0	1	0	7	703	³⁄₄	58	7	³⁄₄	1	0	0	15
344	¹⁄₂	28	8	¹⁄₂	2	0	0	7	709	³⁄₄	59	1	³⁄₄	0	1	0	15
350	¹⁄₂	29	2	¹⁄₂	1	1	0	7	714		59	6		2	0	0	15
358	¹⁄₄	29	10	¹⁄₄	0	0	1	7	720		60	0		1	1	0	15
368	¹⁄₂	30	8	¹⁄₂	1	0	1	7	727	³⁄₄	60	7	³⁄₄	0	0	1	15
370	¹⁄₄	30	10	¹⁄₄	0	0	0	8	738		61	6		1	0	1	15
374	¹⁄₂	31	2	¹⁄₂	0	1	1	7	739	³⁄₄	61	7	³⁄₄	0	0	0	16
380	¹⁄₂	31	8	¹⁄₂	1	0	0	8	744		62	0		0	1	1	15