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7.3.1 Standard Vented Heaters
(Models UHD[X] 75 - 125)
The vent must be fitted with a low resistance
terminal.
. Standard vented heaters do not allow
outdoor air intake for combustion air.
7.3.2 Separated Combustion Heaters
(Models UHD[X]S 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.
. 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.
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.
7.4 Horizontal Venting
Horizontally vented heaters must be individually
vented, no common venting.
Vent pipe must be sloped ¼" (.6 cm) downward for
every 1' (.3 m). For vent lengths greater than 10'
(3 m), condensation will form. Insulation is
recommended and condensation drains may be
desired. For vents pitched up towards the vent
terminal, place the condensation drain within 10'
(3.0 m) of the heater.
In noncombustible walls only, vent terminal
(P/N 02537801-1P) may be used.
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).
7.5 Vertical Venting
Vertically vented standard-vented heaters can be
common vented (up to four heaters).
For vent lengths greater than 10' (3.0 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) UHD[X][S]75 only. 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.
For 4'' (10 cm) common vent, 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,
A vent shall not extend less than 2' (.6 m) above the
highest point where it passes through a flat roof of a
building.
7.6 Length Requirements
If using vent lengths greater than 10' (3.0 m),
condensation will form in the vent pipe. Insulation
and additional sealing measures (high temperature
silicone at all seams) are required.
The entire vent should be insulated with foil faced
fiberglass insulation (1/2" thick, 1-1/2# density
minimum).
7.6.1 Maximum Vent Lengths Table
7.7 Vent Material
Vent material may be single wall 26 ga. (minimum)
galvanized steel or equal thickness stainless steel.
Completely seal all joints, refer to
If penetrating a combustible wall or roof, a listed
thimble with 2" (5 cm) clearance must be used.
Where local codes permit, a single section of type
B-1 vent material may be used at the roof or wall
penetration instead of a thimble. Ensure vent
manufacturer's clearance from vent material is
maintained. Seal annular space of the type B-1 vent
as well as all joints in the remaining vent.
7.8 Replacing an Existing Heater in a Venting
System
When replacing an existing heater in a venting
system, the venting system may not be properly
sized to vent the new heater. The following steps
must be followed with each piece of equipment
connected to the venting system placed in
Model UHD[X][S] 75 - 125
# of Elbows
30 ft (9.1 m)
1
25 ft (7.6 m)
2
20 ft (6.1 m)
3
15 ft (4.5 m)
4
10 ft (3.0 m)
5
