Desa DNV25NB, DNV40NB installation manual Providing Gas Piping to Furnace, Example

OWNER’S MANUAL

INSTALLATION

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Providing Gas Piping to Furnace

You must provide gas piping from gas source to furnace. The gas piping must be in a vertical position where it connects to the furnace. This prevents interference with front cover installation.

Consult your local gas company for proper routing of the gas lines.

Pipe size is determined by the length of pipe from the gas source to the furnace and the total

BTU load on the gas source.

Add the total BTUs required for all appliances connected to the gas source including this furnace.

Divide this number by 1030. This will give you the approximate cubic feet per hour needed.

Example:

40,000 BTU/Hr

+15,000 BTU/Hr for other gas appliances

55,000 BTU/Hr total

55,000 ÷ 1030 = 53.4

Locate 53.4 or higher on chart below.

According to the chart below, you should use 50 feet or less of 1/2" pipe, 200 feet or less of 3/4" pipe, etc...

MINIMUM
IRON PIPE
SIZE						LENGTH OF PIPE (FEET)
	10	20	30	40	50	60	70	80	90	100	125	150	175	200
3/8"	72	49	40	34	30	27	25	23	22	21	18	17	15	14
1/2"	132	92	73	63	56	50	46	43	40	38	34	31	28	26
3/4"	278	190	152	130	115	105	96	90	84	79	72	64	59	55
1"	520	350	285	245	215	195	180	170	160	150	130	120	110	100
11/4"	1050	730	590	500	440	400	370	350	320	305	275	250	225	210
11/2"	1600	1100	890	760	670	610	560	530	490	460	410	380	350	320
2"	3050	2100	1650	1450	1270	1150	1050	990	930	870	780	710	650	610
21/2"	4800	3300	2700	2300	2000	1850	1700	1600	1500	1400	1250	1130	1050	980
3"	8500	5900	4700	4100	3600	3250	3000	2800	2600	2500	2200	2000	1850	1700
4"	17500	12000	9700	8300	7400	6800	6200	5800	5400	5100	4500	4100	3800	3500

IMPORTANT: Check gas line pressure at gas meter before connecting furnace to gas line. Gas line pressure must be no less than 5 inches of water and no greater than 7 inches of water. Gas pressures and input to the burners must not exceed the rated input and pressure shown on the rating plate. For natural gas, manifold pressure should be 3.5 inches of water. For elevations above 2000 feet, reduce rating 4% for each 1000 feet above sea level (U.S.A. only).

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