Schwank duraSchwank - Steel STW-JZ - Manual (Page 31)

31
SPW-JZ, STW-JZ / IWP, IW
I&O Manual IM101229
RL: 12B- BA
RD: AUG 2013
11A. Combined System Length: Tube Heater + Vent + Combustion Air Duct :
MINIMUM VENT LENGTH: (Vented or Unvented)
 Minimum vent length of 3 ft (91 cm) is required (
NOTE: 200,000 LP: Minimum 8 ft (244 cm)
MAXIMUM SYSTEM LENGTH (includes:
Tube Heater length + combustion air duct + vent):
 Each 90° elbow in the system has an equivalent length of 5 ft.
 A maximum of 2 elbows are allowed in any portion (duct, tube heater, vent) with the ex-
ception of up to three 90° elbows in a vertical vent run through the roof
 The maximum length of combustion air duct to any heater is not to exceed 30 feet
 Exceeding the allowable lengths in the table below can create combustion and/or conden-
sation problems and will void CSA Design Certification and the heater warranty.
V ERTICAL VENT THROUGH THE ROOF :
It is the sole responsibility of the installer to
adhere to all current local codes and/or ANSI
Z223.1 / CSA.B149.1 latest editions for all
venting requirements, and practices.
 Use an approved ‘B-vent’ termination cap
as supplied by the manufacturer of the ap-
proved ‘B-vent’.
 When vent and combustion air are taken
through the roof, the exhaust vent should
always terminate higher than the combus-
tion air intake, to prevent recycling the
products of combustion back into the
heater
 At most a quantity of three 90° elbows can be installed in a vertical vent
Approved
Cap
A p p r o v e d
‘B’ Vent
24”
60 cm
12
9
If roof slope exceeds 9:12
consult NFPA-54 ANSI
Z223.1 or CSA-B149.1
FIGURE 22
Up
to
Input
(Btuh)
Max. Combined
System Length*
Do Not Exceed
Max. Vent
Length*
Max. Air Duct
Length*
45,000 60 ft Up to 30 ft Up to 20 ft
60,000 60 ft Up to 30 ft Up to 30 ft
80,000 80 ft Up to 40 ft Up to 30 ft
110,000 100 ft Up to 40 ft Up to 30 ft
130,000 100 ft Up to 40 ft Up to 30 ft
150,000 100 ft Up to 40 ft Up to 30 ft
175,000 120 ft Up to 50 ft Up to 30 ft
200,000 120 ft Up to 50 ft Up to 30 ft
* Do not exceed the Maximum Combined System Length regardless of the allowed maximum
length of individual vent or combustion air duct
Example
150,000 Btuh Heater:
Tube Heater Length 50 ft
1 x 90° elbow (vent) 5 ft
Straight vent 20 ft
1 x 90° elbow (duct) 5 ft
Air Duct 17 ft
Combined Length 97 ft
Max. Allowed 100 ft