![background image](http://html1.mh-extra.com/html/thermo-pride/cdb1-100n/cdb1-100n_installation-and-operation-manual_1104450016.webp)
All installations and services must be performed by qualified service personnel.
10
8. The maximum quantity of schedule 40, type DWV thermoplastic pipe elbows allowed in each
system is listed in Table 2. When counting pipe elbows,
all
elbows used in the exhaust vent or
combustion air intake systems must be considered. This includes all elbows, or equivalent
pipefittings, used inside the furnace jacket in addition to those used to construct the termination.
Furthermore, a credit of 5-feet of straight pipe may be taken for each elbow, up to maximum of
three (3) elbows, which is dropped from the maximum permissible number for each system.
Table 2: Maximum Permissible Exhaust Vent and Combustion Air Intake Lengths When Using the
Maximum Quantity of Elbows
Thermoplastic
Pipe Vent Size
(Nominal)
2 in. Diameter
3 in. Diameter
Furnace Model
Exhaust or
Intake
Straight
Pipe
Length (ft.)
Maximum
Qty. of
Exhaust
Elbows
1,2
Maximu
m
Qty. of
Intake
Elbows
2
Exhaust or
Intake
Straight
Pipe
Length (ft.)
Maximum
Qty. of
Exhaust
Elbows
1, 2
Maximu
m
Qty. of
Intake
Elbows
2
CHB1 / CDB1-50
CHB1 / CDB1-75
35 8 7
- - -
CHB1 / CDB1-100
CHB1 / CDB1-125
Not Permitted
35
8
7
Notes:
1
The drain tee supplied with CHB1 / CDB1 furnace model series is considered equivalent to
one (1), 90° elbow.
2
Two (2), 45° elbows can be substituted for one (1), 90° elbow.
Care should be taken to design the shortest possible intake and exhaust systems. Each system
should contain as few elbows as possible to insure the satisfactory operation of the furnace.
However,
system length should never be less than 8 ft of pipe with two (2), 90 deg. elbows
.
For best overall operation of the combustion system, we recommend the actual equivalent lengths
for both the constructed intake and the exhaust systems have approximately the same value.
9. Use a saw designed to cut thermoplastic pipe. All cuts should be made at right angles to the pipe
wall. Smooth jagged edges and remove all burrs and strings.
All pipe joints must utilize
standard PVC schedule 40, DWV type elbows, couplings, and fittings.
Clean all pipe surfaces
at connections using a fine abrasive material or approved PVC cleaner (primer). Secure all
pipe
joints using suitable permanent PVC pipe solvent cement. Joints are
NOT
to be made by simply
gluing raw edges of butted together vent pipe.
Piping joints inside the furnace vestibule should be sealed with silicone caulk, rather than pipe
cement, to allow for disassembly and removal of piping, if necessary, during maintenance.
NOTICE: DO NOT use silicone caulk to seal the pipe sleeve or coupling to the metal air
intake collar on the burner box. Securing the sleeve or coupling to the collar using a screw
is sufficient.
10. Vent connections shall be checked for leakage with the furnace induced draft blower running and
with the vent termination blocked. Use a mild soap and water solution to check for leaks.
11. Vent pipe passing through an unheated space shall be insulated with 1-inch thick, foil-faced
fiberglass insulation, or equivalent, to prevent freezing of condensate within the pipe.