WHL-001 Rev. 001 Rel. 008 Date 8.23.18
19
E. Exhaust Vent and Intake Pipe Sizing
1. The exhaust vent and intake pipe size is 2”.
2. The total equivalent length of exhaust vent and intake pipe
should not exceed 150 feet
.
a. The equivalent length of elbows, tees, and other fittings are
listed in the Friction Loss Table.
Friction Loss Equivalent in Piping and Fittings
Fittings or Piping
Equivalent Feet
2”
3”
90 Degree Elbow*
5’
5’
45 Degree Elbow
3’
3’
Coupling
0’
0’
Air Inlet Tee
0’
0’
Straight Pipe
1’
1’
Concentric Kit
3’
3’
V500 2” Kit
1’
N/A
V1000 3” Kit
N/A
1’
V2000 4” Kit
N/A
1’
Table 7 - *Friction loss for long radius elbow is 1 foot less. NOTE: Consult
Polypropylene venting instructions for friction loss and pressure drop
equivalents.
b. For example: If the exhaust vent has two 90
o
elbows and 10
feet of PVC pipe we will calculate:
Exhaust Vent Equivalent Length = (2x5) + 10 = 20 feet.
Further, if the intake pipe has two 90
o
elbows, one 45
o
elbow,
and 10 feet of PVC pipe, the following calculation applies:
Intake Pipe Equivalent Length = (2x5) + 3 + 10 = 23 feet.
Finally, if a concentric kit is used we find:
Total Equivalent Length = 20 + 23 + 3 = 46 feet.
The total equivalent length is 46 feet, well below the maximum
of 150 feet.
c. Effort should be made to keep a minimum difference in
equivalent length between the exhaust vent and intake pipe.
3. The minimum total equivalent length is 16 feet.
Do not exceed the maximum lengths for vent pipes. Excessive
length could result in heater shutdown and property damage.
Failure to provide a minimum total vent length of 16 equivalent
feet could result in property damage and improper product
operation.
F. Longer Vent Runs
The maximum total equivalent length can be extended by increasing
the diameter of both the exhaust vent and intake pipes. However,
the transitions should begin a minimum of 15 equivalent feet from
the water heater.
a.
The maximum total equivalent length for increased
diameter vent pipes is 200 feet.
b. Transitions should always be made in vertical sections of pipe
to prevent the condensate from pooling in the vent pipe.
Vent Connection
Reducing Coupling
Vent Transition
2”
3” x 2”
3”
Table 8 - Vent Run Transition
c. Transition from 2” to 3” pipe should be made at the water
heater.
G. Exhaust Vent and Intake Pipe Installation
All joints of positive pressure vent systems must be sealed completely
to prevent leakage of flue products into the living space. Failure to
do so could result in property damage, serious injury, or death.
1. Use only solid PVC or CPVC pipe or a Polypropylene vent system
approved for use with Category IV appliances.
FOAM CORE PIPING IS NOT APPROVED FOR EXHAUST VENT
APPLICATIONS. Foam core piping may be used on air inlet piping
only
.
2. Remove all burrs and debris from joints and fittings.
3. When using PVC or CPVC pipe, all joints must be properly cleaned,
primed, and cemented. Use only cement and primer approved for
use with the pipe material. Cement must conform to ASTM D2564
for PVC and ASTM F493 for CPVC pipe.
NOTE: DO NOT CEMENT
POLYPROPYLENE PIPE.
4. Ensure the vent is located where it will not be exposed to prevailing
winds.
5. In all roof venting applications, exhaust discharge must point away
from the pitch of the roof.
6. To prevent water leakage, install adequate roof flashing where the
pipe enters the roof.
7. Do not locate vent over public walkways, driveways, or parking lots.
Condensate could drip and freeze, resulting in a slip hazard or damage
to vehicles and machinery.
8. Due to potential moisture build-up, sidewall venting may not be
the preferred venting option. To save time and cost, carefully consider
venting installation and location.
9. Horizontal lengths of exhaust vent must slope back towards the
water heater not less than ¼” per foot to allow condensate to drain
from the vent pipe.
10. The exhaust vent must terminate where vapors cannot make
accidental contact with people or pets, or damage shrubs or plants.
11. In vacant chimney applications, install and seal a rain cap over
existing chimney openings.
12. All piping must be fully supported. Use pipe hangers at a minimum
of 4 foot intervals to prevent sagging of the pipe where condensate
may form.
13. Do not use the heater to support any piping.
14. A screened straight coupling is provided with the heater for use as
an outside exhaust termination.
15. A screened inlet air tee is provided with the heater to be used as
an outside intake termination.
16. Maximum Snow Level Determination: These installation
instructions reference snow levels in establishing a minimum height
for the installation of exhaust vent or air intake terminations. Snow
levels shall be determined as follows:
a. The installation location may, by ordinance, designate how snow
levels are calculated in that location; or
b. In the absence of specific ordinances, snow levels shall be calculated
from the average monthly maximum depth of snow accumulation as
indicated by the National Weather Service’s 10 year statistics for the
installation location/geographical area.
In addition:
•
Total length of vent piping shall not exceed the limits specified
in this manual.
•
The vent piping for this direct vented appliance is approved for
zero clearance to combustible construction.
•
The flue products coming from the exhaust vent will create a
large plume when the heater is in operation. Avoid venting in
areas that will affect neighboring buildings or be considered
objectionable.
•
DO NOT locate exhaust vent or intake pipe in a parking area
where machinery may damage the pipe.
