Innovation Water Heaters
– Edge [i] Controller
Venting and Combustion Air Design Guide
TAG-0090_A
•
GF-5056
•
2/20/2020
Technical Support
•
(800) 526-0288
•
Mon-Fri, 8 am - 5 pm EST Page 38 of 39
Example using standard North American units of measure:
1) An installer is trying to figure out if he can save some money by using a 4-inch vent
(exhaust) design versus a 6-inch when installing a single Innovation 600N water heater.
After laying out the design, he determines he needs the following components:
a) A 15-foot length of combustion air pipe with one (1) sharp 90° elbow plus (2) two
termination 90° elbows.
b) A 35-foot length of vent pipe and two (2) sharp 90° elbows plus a termination
(exit cone or rain cap).
Intake (must use 6-inch):
From
Table 5
for 6-inch piping we will design the inlet for maximum outside air temperatures
(100
°
F):
Max outside air Temp = 100
°
F
p straight pipe = 0.24 ft./ft.
p 90° elbow = 1.24 ft./elbow
p entrance loss = 1.94 ft.
Intake
p equivalent feet = 15 ft. x 0.24 ft./ft. + 3 elbows x 1.24 ft./elbow + 1.94 ft. = 10 feet
Vent
using 6” pipe (Exhaust):
From
Table 9
for 6-inch piping:
p straight pipe = 0.3 ft./ft.
p 90° elbow = 1.7 ft./elbow
Velocity cone or Rain cap = 3 ft.
Exhaust
p equivalent feet = 35 ft. x 0.3 ft./f.t + 2 elbows x 1.7 ft./elbow + 3 ft. = 17 feet
Vent using 4” pipe (Exhaust):
From
Table 9
for 4-inch piping:
p straight pipe = 2.2 ft./ft.
p 90° elbow = 12.1 ft./elbow
Velocity cone or Rain cap = 19.7 ft.
Exhaust
p equivalent feet equals:
35 ft. x 2.2 ft./ft. + 2 elbows x 12.1 ft./elbow + 19.7 ft. =
121 feet > 80 feet --FAIL--
i)
Total equivalent feet of intake (6-inch) and vent (6-inch) =
10 ft. + 17 ft. = 27 ft. --OK--
ii)
Total equivalent feet of intake (6-inch) and vent (4-inch) =
10 ft. +
121 ft.
= 131 ft.
> 80
feet --FAIL--
Only the 6-
inch design is approved. Note that the 4” vent pipe design failed even
though the total equivalent feet for the combined intake and vent system was less
than 140 feet. The 4 inch vent design exceeded the equivalent 80 foot maximum.
