SECTION 6: VENTING
Vents and air intakes must be adequately supported so that the heater does not bear the weight of the pipes.
For vent termination See Page 13, Figure 6 through Page 16, Figure 11.
6.3.1Standard Vented Heaters (Models UHD[X][R] 75 - 125)
The vent must be fitted with a low resistance terminal. See Page 13, Figure 6 through Page 13, Figure 7. Standard vented heaters do not allow outdoor air intake for combustion air.
6.3.2Separated Combustion Heaters (Models UHD[X]S[R] 75 - 125)
The heaters are designed to be installed as separated combustion heaters. The vent and air intake are run as separate pipes to the wall or roof terminals. See Page 15, Figure 9. As an option, the vent and air intake are run as separate pipes to a concentric vent box and a concentric vent/air intake pipe penetrates the wall or roof. See Page 15, Figure 10 and See Page 16, Figure 11.
For separated combustion installation, the vent and air intake must be fitted with an individual and correctly sized sealed system and the vent and air intake must terminate at approved wall and roof terminals.
Separated combustion units may not be common vented. See Page 10, Section 6.
6.4 Unvented Operation
WARNING
Carbon Monoxide Hazard
Heaters may be installed vented or unvented.
Vented heaters must be vented outdoors.
Unvented heaters must be installed in buildings with ventilation rates as per section 6.4.
Failure to follow these instructions can result in death or injury.
This heater is not approved to be installed in residential buildings.
For unvented operation in commercial installations, sufficient building ventilation must be provided in the amount of 4 cfm per 1000 Btu/h firing rate (United
States); 3 cfm per 1000 Btu/h firing rate (Canada).
WARNING: Combustion
6.5 Horizontal Venting
Horizontally vented heaters must be individually vented.
Vent pipe must be sloped ¼" (.6 cm) downward for every 1' (.3 m). For vent lengths greater than 5' (1.5 m), condensation will form. Insulation is recommended and condensation drains may be desired.
In noncombustible walls only, vent terminal (P/N
For 4'' (10 cm) vents in either combustible or noncombustible walls, use vent terminal (P/N 90502100) or equivalent insulated vent terminal. Follow the manufacturer's instructions for proper installation.
Instead of an insulated vent terminal, a listed thimble (with 2" (5 cm) air gap) may be used with a 4" (10 cm) vent cap (P/N 90502102).
6.6 Vertical Venting
For vent lengths greater than 5' (1.5 m), condensation will form. Insulation is recommended and condensation drains may be desired. Venting through the top of the heater cabinet is not recommended if vent lengths are longer than
10' (3 m). In this case, vent from the rear of the heater cabinet then run the vent vertically and use a condensate drain at the bottom of the vertical vent. Vent pipe must be sloped 1/4'' (.6 cm) for every
1' (.3 m).
For 4'' (10 cm), an approved vent cap (P/N 90502102) must be used.
For 6'' (15 cm) common vent, an approved vent cap (P/N 90502103) must be used.
For common vertical venting of more than two heaters, See Page 14, Figure 8.
A vent shall not extend less than 2' (.6m) above the highest point where it passes through a flat roof of a building.
6.7 Length Requirements
If using vent lengths greater than 5' (1.5 m), condensation will form in the vent pipe. Insulation
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