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TABLE 4 COMBINED SYSTEM LENGTH: TUBE + AIR DUCT + VENT
Do Not Exceed
Maximum Combined
Modulating
System Length
Maximum
With 4"
Input (Btuh)
Air Duct
80,000
70 ft
115,000
80 ft
155,000
90 ft
205,000
Use 5"Ø
250,000
Use 5"Ø
HEATER EXPANSION AND VENT CONFIGURATION
A radiant tube heater will expand and contract as it heats and cools. Configuration of the vent must
allow for heater expansion.
VERTICAL VENT: Orientation of the vent at 90° to heater will allow for heater expansion and
contraction.
HORIZONTAL VENT: (See FIG. 7)
Wall Thimble or flashing at wall
◼
that allows movement of the vent
through the opening. Do not seal
the vent to the thimble or flashing
with caulking
OR
Offset vent with two x 90° elbows.
◼
Install minimum 12 inch [305 mm]
length of straight vent between
elbows. Vent can be sealed with
caulking at non-combustible wall.
Other means of slip fit installation
◼
of the vent are acceptable provid-
ing there is adequate allowance
for free expansion and contraction
of the system, and free flow of
vent gases.
COMMON VENTING
For vertical vent only, two heaters can be commonly vented using 4"x 6"x 4" Vent Tee 902000008.
Both heaters must be operated using one common thermostat. Common vent is 6 inch [150 mm] di-
ameter.
Category III (horizontal vent) heaters cannot be common vented.
HE+ Series Modulating Supplemental Manual
Max. Air Duct
Length
(by Duct Diameter)
With 5"
4" Ø
Air Duct
80 ft
20 ft
90 ft
20 ft
100 ft
20 ft
Use 5"Ø
110 ft
120 ft
Use 5"Ø
FIGURE 7: ALLOW FOR HEATER EXPANSION
14
Max. Vent
Length
Individual: 4"Ø
OR
5" Ø
Combined: 6"Ø
30 ft
30 ft
30 ft
30 ft
30 ft
30 ft
30 ft
30 ft
30 ft
30 ft
- HORIZONTAL VENT - TOP VIEW
Example
155,000 Btuh Heater:
Tube Heater Length
1 x 90° elbow (vent)
Straight vent
1 x 90° elbow (duct)
Air Duct: 4" Ø
Combined Length
Max. Allowed
Additional 10' for 5" Ø Air Duct
50 ft
5 ft
15 ft
5 ft
15 ft
90 ft
90 ft
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