C. Replacing Existing Furnace From A Common Vent - Thermo Pride CLHS1-050P36N Installation And Operation Manual

All installations and services must be performed by qualified service personnel.

C. REPLACING EXISTING FURNACE FROM A COMMON VENT

: These furnaces may NOT be common vented with any other appliance.
D. GENERAL REQUIREMENTS FOR VENTING
The furnace venting system must be installed by a qualified service person in accordance with local installation
codes and these instructions. In the absence of applicable local codes, conform to the National Fuel Gas Code, NFPA
54 /ANSI Z223.1-2002, or latest edition thereof.
Provide adequate combustion and ventilation air to the furnace space as specified in Section III parts D through H.
Installation shall, at least, conform to the following requirements.
1. The exhaust vent / combustion air intake terminations specified by Thermo Products, in this manual, shall
be used.
2. All plastic pipe and pipefittings sourced to complete the exhaust vent and air intake systems shall be
constructed of rigid PVC (polyvinyl chloride) thermoplastic. All components shall have a wall thickness
equivalent to Schedule 40 series materials.
In addition, all sourced PVC components shall be listed by a nationally recognized testing agency (e.g.
NSF, UL, etc.) as conforming to one (1) or more of the following design standards.
3. The exhaust vent pipe and combustion air pipe shall be at least as large as the exhaust vent / air intake pipe
specified by Thermo Products. Size reduction is never permissible. The required exhaust vent / air intake
pipe sizes are:
•
2-inch PVC thermoplastic pipe, for models CLHS1–050/075 & CLHX1-050/075
•
3-inch PVC thermoplastic pipe, for models CLHS1–100/125 & CLHX1–100/125
4. All horizontal runs of exhaust vent pipe shall slope upward at least ¼ inch per foot from the outlet of the
furnace to the vent termination, beyond the outside wall. This slope will permit proper drainage of the
condensate.
Horizontal runs of air intake pipe shall slope downward at least ¼ inch per foot from the outlet of the last
elbow or last horizontal run, before exiting the wall, to the intake termination beyond the outside wall. This
slope will permit proper drainage of any precipitation that enters the intake pipe.
5. The exhaust vent pipe shall be supported at every joint (no more than 4-feet between supports) to prevent
pipe blockage due to condensate trapped at a local low point, or sag, in the vent system.
PVC Pipe Designation
Cellular Core
DWV (Drain-Waste-Vent)
Schedule 40
Design Standard
ASTM-F891
ASTM-D2665
ASTM-D1785
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