Roberts Gorden TF-120 Vertical Venting, Unvented Operation Tube Termination, Length Requirements

TF-SERIES INSTALLATION, OPERATION AND SERVICE MANUAL

9.4 Vertical Venting

For 4" (10 cm), an approved vent cap (P/N 90502300) must be used.

For 6" (15 cm) common vent, an approved vent cap (P/N 90502302) must be used.

A vent shall not extend less than 2' (0.6m) above the highest point where it passes through a flat roof of a building.

9.5 Unvented Operation Tube Termination

Turndown type vent terminal with a screen must be installed at the exhaust end of the tube. Vent terminal design shall not incorporate backdraft flap.

FIGURE 22: Tube Termination

9.6 Length Requirements

The maximum vent length, where both tubes are

vented together is 45’ (13.7 m) of 6" (15 cm) diameter duct. The maximum vent length, where both tubes are vented individually is 45’ (13.7 m) of 4" (11 cm) diameter duct, or 22.5’ (7 m) on each tube.

The maximum outside air supply duct length allowed is 45’ (13.7 m) of either 4" (10 cm) or 5" (13 cm) diameter, however the maximum length depends on the venting arrangement used.

The total vent length, plus outside air duct length, plus any extensions to minimum heat exchanger lengths, cannot exceed 65' (19.8 m).

Vent length should be limited to less than 20' (6 m). If using vent lengths greater than 20' (6 m), condensation will form in the vent pipe. Insulation and additional sealing measures (high temperature silicone at all seams) are required. Optional heat exchanger lengths are considered as vent length for length determination.

Subtract 15' (4.6 m) of maximum allowed vent or duct length per vent elbow if more than two are used.

9.7 Horizontal Ventilation 4" (10 cm) Pipe

SIDE VIEW		Combustible or
		Non-Combustible
	Burner	Wall
		Flexible	Vent Terminal
		Boot
	Tube		Approved
		Single Wall	Wall
	Install with boot	Vent Pipe	Thimble
	extended

Description	Part Number
Flexible Boot	91412800
Boot Clamp	91901300
Vent Terminal (Comb. Wall)	90502100
Vent Terminal	02537801-1P
Vent Sleeve	09080000

4" (10 cm) Single Wall Pipe	Metalbestos
	Cap
Non-Combustible	18" (46 cm)
	Min.
Wall
4" (10 cm) Single Wall Pipe	Vent Terminal

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