Combustion Air Duct - Schwank SET - SETU Owner's Manual

V
ERTICAL VENT THROUGH THE ROOF
It is the sole responsibility of the installer to ad-
here to all current local codes and/or ANSI
Z223.1 / CSA.B149.1 latest editions for all vent-
ing requirements, and practices.

Use an approved 'B-vent' termination cap as
supplied by the manufacturer of the approved
'B-vent'.

When vent and combustion air are taken
through the roof, the exhaust vent should al-
ways terminate higher than the combustion
air intake, to prevent recycling the products of
combustion back into the heater.
11A. Combined System Length: Tube Heater + Vent + Combustion Air Duct
MINIMUM VENT LENGTH: (Vented or Unvented)

Minimum vent length of 3 ft x 4" [91 cm x 100 mm] diameter is required
MAXIMUM SYSTEM LENGTH (includes:

Each 90° elbow in the system has an equivalent length of 5 ft (air duct, tube, or vent pipe).

A maximum of 2 elbows are allowed in any portion of air duct, tube heater, vent pipe, with
the exception of up to three 90° elbows in a vertical vent run through the roof

Vent pipe diameter shall be 4" [100 mm] for a single heater, or 6" [150 mm] combined vent
for two heaters - do not substitute any other vent diameter

The maximum length of combustion air duct to any heater is not to exceed 30 feet of 4 inch
[100 mm] diameter duct or 50 ft x 5" diameter duct

Exceeding the allowable lengths in the table below can create combustion and/or conden-
sation issues and will void CSA Design Certification and the heater warranty.
Do Not Exceed
Max. Combined
Input
System Length*
(Btuh)
4" Air Duct 5" Air Duct
80 / 60,000
80 ft
110 / 75,000
100 ft
130 / 90,000
100 ft
155 / 110,000
100 ft
175 / 125,000
120 ft
200 / 140,000
120 ft
* Regardless of the allowed maximum length of the individual vent or combustion air duct, do
not exceed the Maximum Combined System Length which includes the length of the tube
heater plus the air duct and the vent.
:
Tube Heater length + combustion air duct + vent
Max. Vent
Length*
Individual: 4" Ø
Combined: 6" Ø
100 ft Up to 40 ft
120 ft Up to 40 ft
120 ft Up to 40 ft
Up to 40 ft
120 ft
140 ft Up to 50 ft
140 ft Up to 50 ft
FIGURE 19
Approved
Cap
Approved
'B' Vent
Max. Air Duct
Length*
(by Duct Diameter)
4" Ø 5" Ø
30 ft 50 ft
30 ft 50 ft
30 ft 50 ft
30 ft 50 ft
30 ft 50 ft
30 ft 50 ft
25
24"
Up
9
60 cm
to
12
If roof slope exceeds 9:12
consult NFPA-54 ANSI
Z223.1 or CSA-B149.1
Example
155/110,000 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
SET(U)-F / ITT(U)-F Manual
RD: FEB 2014
:
):
50 ft
5 ft
20 ft
5 ft
17 ft
97 ft
100 ft
IM091221
RL: 8B