Installation Instructions

Installation | 23
6 720 805 218 (2016/02)SB625WS/SB745WS
5.5 Combustion gas exhaust
The flue gas exhaust and stack connection must be made in compliance
with applicable laws and standards, using heat resistant, condensate
resistant and stress resistant rigid pipe and sealed joints.
The stack must be fitted with a condensate trap and drain and the flue
gas exhaust pipe must be installed at a slope of at least 2° towards the
boiler. All condensate should be treated through a neutralization media
before being eliminated to the floor drain.
Fig. 22 Typical installation schematic
5.6 Venting Requirements
The SB Boiler is a category II or IV appliance and the exhaust vent
materials must be UL listed for use with a category IV appliance:
operating temperatures of up to 240 °F, positive pressure, condensing
flue gas service. Currently, UL Listed vents of AL29-4C or 316L stainless
steel must be used with the SB Boiler. Proper clearances to
combustibles must be maintained per UL and vent manufacturer
instructions.
The vent system should be designed to facilitate smooth travel for both
the intake and exhaust. Avoid the use of bullhead tees and back-to-back
90 degree elbows. The exhaust system must never be installed in a
downward fashion. Be sure to follow all instructions provided by the vent
manufacturer.
Keep the supply of combustion air free of corrosive substances (e.g.
halogenated hydrocarbons that contain chlorine or fluorine
compounds). This will help prevent corrosion. Never use or store
chlorinated cleaning agents or halogenated hydrocarbons (as contained
in spray cans, solvents or cleaning agents, paints and adhesives, for
example) in the boiler room.
UL, NFPA 54 & 211, ANSI Z223.1 (USA) and CGA-B.149.1 and 2
(Canada) guidelines are often the basis for state and local codes. Follow
the guidelines of these recognized agencies unless codes applicable to
the installation site are most stringent. The venting and combustion air
systems must meet all applicable code requirements. Where code
differs from the instructions provided with the equipment, code will take
precedence.
Constant pressure at the flue gas outlet is not required. Size the flue
system to limit pressure variations. The maximum allowable breech
pressure for design of the flue system is positive 0.2" W.C. for proper
combustion and light off.
A draft control system may be required to ensure proper draft when two
or more boilers are connected to a common stack. Consult the flue
material manufacturer for design calculations and recommendations.
H
ø i
6 720 805 218-26.1T
Description Symbol Unit SB625WS SB745WS
160 220 290 370 480 640 800 1050 1300 1550
Height of flue
gas outlet
H inch
[mm]
19 7/8
(505)
19 7/8
(505)
21 1/6
(535)
21 1/6
(535)
25
(635)
25
(635)
26 3/4
(680)
26 3/4
(680)
28 3/8
(720)
31 11/18
(805)
Diameter of flue
gas fitting
Ø i [mm] 200 200 250 250 300 300 350 350 400 450
Table 10 Combustion gas exhaust
WARNING: Risk of system damage or personal injury!
The vent system could fail, causing flue gas spillage,
resulting in severe personal injury or death.
▶ Use only an approved vent starter coupling and
approved vent pipe from the same manufacturer for
Buderus SB boilers.
▶ Do not mix components from different systems.
NOTICE: Risk of system damage!
▶ Connect an oil-fired unit to a vent having sufficient
draft at all times to ensure safe and proper operation
of the unit.
The specifying engineer should dictate flue venting as
appropriate to the installation.