LP-719 Rev. 000 Rel. 000 Date 6.25.20
41
2. Venting Through an Existing System
This boiler may be vented through an existing unused vent system.
The inner diameter of the existing vent system is utilized for the
combustion air source. Two methods have been approved for such
venting: Concentric Venting Through an Existing System and Venting
as a Chase.
Table 17 - Minimum Existing Vent / Chase Sizing
DANGER
!
Do not install the boiler into a common existing vent with any other
appliance. This will cause flue gas spillage or boiler malfunction,
resulting in substantial property damage, serious personal injury,
or death.
SEAL
SEALED
EXISTING
EXHAUST
CAP
(w/SCREEN)
SEAL
AIR INTAKE
SEAL
LP-325-LL
03/15/12
Exhaust
In
take
Concentric Venting through an Existing System
1
12" MIN.
LP-325-MM
03/15/12
EXHAUST
SEAL
w/SCREEN
EXISTING
AIR INTAKE
SEALED CAP
COMBUSTION AIR
COMBUSTION
AIR
SEAL
Concentric Venting through an Existing System
2
In
take
Exhaust
Exhaust
In
take
24"
LP-700-B
03/27/19
AIR INLET
EXHAUST
EXISTING
VENT
SEAL
CAP
SEAL
Chase Venting Through an Existing System
3
Figure 42 - 1, 2 - Concentric Venting Through an Existing System, 3, Chase Venting Through an Existing System
NOTE:
These drawings are meant to demonstrate system venting only. The installer is responsible for all equipment and detailing required
by local codes.
Contractors must check state and local codes before installing
through an existing vent opening. State and local codes always take
precedence over manufacturer’s instructions. Failure to check state
and local codes before installing through an existing opening could
result in property damage and add significantly to installation costs.
CAUTION
If an existing venting system is converted for use with this boiler,
the installer must ensure that the existing venting system is clean
and free from particulate contamination that could damage the
boiler. Failure to do so could result in property damage and boiler
failure. Such failure IS NOT covered under warranty.
Concentric Venting Through an Existing System
NOTE: The following instructions refer only to venting through
an existing vent system, and not to venting with HTP’s optional
concentric vent kits. Refer to Concentric Vent Kit installation manual
(LP-166) for further information on venting with the optional
concentric vent kits.
Concentric venting through an existing system must run vertically
through the roof. See Table 17 for proper minimum vent sizing. Use
only the approved venting materials specified in Table 11 for piping
the system. All instructions listed in this Venting section apply. See
Figures 42-1 and 42-2 for venting demonstrations.
The upper and lower vent terminations as well as all joints in
the venting system must be properly sealed to ensure that all
combustion air is drawn properly and exhaust does not leak from
the system. Failure to properly seal the venting system will result in
property damage, serious personal injury, or death.
Chase Venting Through an Existing System
When venting as a chase, follow all instructions included in this
Venting section, including those in the previous Concentric Venting
Through an Existing System section. See Figure 42-3 for chase
venting demonstration.
Vent / Air Inlet Size
Minimum Existing Vent / Chase Size
2”
4”
3”
5”
