Rinnai E110CP, E75CN, E110CN, E75CP Combustion air and vent piping lengths, Parallel system

6.7.6 Combustion air and vent piping lengths.

In the table below you find the maximum equivalent pipe length of the vent/air system based on 3" diameter. These lengths are for single pipe (room air), twin pipe, and concentric venting systems.

	Boiler type	3” Max Vent equivalent length	3” Max Air equivalent length
	E75	100 feet	100 feet
	E110	100 feet	100 feet
Equivalent vent length			table 9

Calculation of equivalent length vent system

Choose the vent type and fill out the corresponding table.

*When determining equivalent combustion air and vent length, add 6 feet for each 90° elbow, 3 feet for each 45° elbow, 5 feet for the concentric terminal in the Parallel System, and 2 feet for the concentric terminal in the Concentric System .

Parallel system

Length tube	Number of	Number of	Concentric	Total	Multiply with	Equivalent
	elbows 90°	elbows 45°	terminal		factor	length
	x 6*	x 3*	Add 5 ft.*
Combustion air
ft	ft	ft	ft	ft	0.5	ft
Vent

ft ft ft ft ft 0.5

Total equivalent length

Concentric system

ft ft

	Length concentric	Number of		Number of	Concentric		Total		Multiply with Total equivalent
	tube, boiler to roof	elbows 90°		elbows 45°	terminal					factor	length
	horizontal		x 6*	x 3*	Add 2 ft.*
	ft		ft	ft		ft		ft		1.0	ft
			Example of calculation:
			Twin tube (parallel) with terminal
				Combustion air length		: 24 ft	with elbow 3 x 90°
				Vent length		: 24 ft	with elbow 2 x 90°, elbow 2 x 45°
Installation & Servicing Instructions Rinnai E-Series			Calculation:
			Equivalent Air Length		: (24+3x6+2) x 0.5			=		23 ft
			Equivalent Vent Length		: (24+2x6+2x3+2) x 0.5			=		23 ft +Total =	46 ft.

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