ITH-Series Technical Manual
Page 26
Cambridge
Engineering
Inc.
Venting / Combustion Air Ducting
Vented Operation
In all cases, be sure vent pipes and outside air supply ducts are sealed with approved sealant, such as high
temperature RTV silicone. Double wall venting (B vent) may not require sealant.
Horizontal Venting
When venting through combustible walls, use approved vent terminal Tjernlund VH1-4, or
Cambridge Engineering supplied deflector vent terminal with an approved insulating thimble.
When venting through non-combustible walls, use supplied deflector vent terminal.
Recommended extension of the terminal past the outside wall surface is 18" minimum.
Figure 24: Horizontal Venting
Vertical Venting
Minimum vent pipe size is 4" for an individual heater. Additional vent pipe sizes, as required to
accommodate multiple heaters venting through a common roof vent, are defined in the appropriate
gas installation code. (Refer to common venting section below).
Use of an approved thimble to pass through combustible roof materials is required.
Use of an approved vent cap is required.
Check local codes for vertical vent size for fan-assisted appliances.
Common Vertical Venting
Common vent sizing information is defined in the appropriate gas installation code (Refer to
ANSI Z223.1 for sizes and installation information).
For vertical venting refer to ANSI Z223.1 Fan Assisted Category 1 Appliances.
Connection locations to the common vent should be offset to avoid pressure interferences between
heaters, refer to ANSI Z223.1 Fan Assisted Category 1 Appliances.
NON-COMBUSTIBLE WALL
MAX. 30'
WITH 2 ELBOWS
4" VENT
TERMINAL
P/N CMCT011
NOTES:
- 4" WALL THIMBLE AND 4" VENT TERMINAL
MUST BE USED WITH SINGLE WALL VENTING
THROUGH A COMBUSTIBLE WALL.
4" WALL THIMBLE
P/N CMCS006
COMBUSTIBLE WALL
MAX. 30'
WITH 2 ELBOWS
4" VENT TERMINAL
P/N CMCT011
14" MIN.
14" MIN.
