Rinnai RUR98i Mode D'emploi page 23

IMPORTANT CONSIDERATIONS FOR LOCATION (con nued):
Exhaust and Combusti n Air Intake Pipe Diameters and Maxi-
mum Lengths:

For PVC/CPVC vent systems reduce the maximum
allowable length for each elbow and terminati n type as
follows:

2.5 feet for every 45° elbow.

5 feet for every 90° elbow.

Terminati n (refer to the Approved Vent
Component table of this secti n)

Vent and combusti n air intake pipe diameters to be as
specifi d in the maximum equivalent vent length tables in
this manual.

Do not exceed vent and combusti n air intake pipe MAXI-
MUM lengths (Lengths are specifi to models and
fuel type).
Determining Total System Equivalent Length
There are two opti ns for determining the vent lengths/
components necessary for the installati n.
Op on 1: The installer can use the vent length calculati n sheet
(below), filling in the quanti y of the vent components in order
to calculate the total equivalent vent lengths.
Op on 2: The installer can use the maximum vent lengths tables
on the next pages to determine the amount of straight pipe that
can be used with a specifi terminati n type and quanti y of
elbows.
OPTION 1:
Calcula on of equivalent piping lengths for venti g system:
Choose the vent type and fill out the calculati n sheet
Fi g / Terminati n Type
1) 90 elbow
2) 45 elbow
3) IPEX Low Pro le Termina on
4) IPEX 4" Concentric Termina on
5) IPEX 3" Concentric Termina on
Royal 3" Concentric Termina on
6)
Royal Low Pro le Termina on
7)
8) 3" Tee Termina on
9) 4" Tee Termina on
10) 3" Snorkel Termina on
11) 4" Snorkel Termina on
12) Length of Straight Secti n in feet
(A blank copy of the Equivalent Vent Length Calculati n Sheet is located at the end of this sec on)
Ensure SW1 in DIPSW 1 is in OFF positi n if vent length is greater than 21ft (6.4m).
Equivalent Vent Length Calcula on Sheet
Number of
fi ngs
3
1
NA
KBP Series Manual
below. When determining equivalent combusti n air and vent
length, add 5 feet for each 90° elbow, 2.5 feet for each 45° elbow.
Example of calculati n (assume 3" diameter pipes for natural gas
unit):

Twin pipe (parallel) with snorkel terminal

Combusti n air pipe length: 40 ft straight pipe with 3 x 90°
elbows

Exhaust pipe length: 40 ft straight pipe with 3 x 90° elbows
(include all interior and exterior elbows)

Snorkel Terminati n: 10 equivalent feet (reference Approved
PVC/CPVC Terminati n Components table)
Calcula on:

Equivalent Combusti n air pipe length: *40+(3 X 5)+10+ = 65 ft

Equivalent Vent Length: *40+(3 X 5)+10+ = 65 ft

Total = 65 ft. for both exhaust and combusti n air pipes,
which is the maximum allowable vent length for 3" PVC/CPVC
on a natural gas unit. If longer lengths are required, go to the
4" diameter pipe config rati n which is certifi
equivalent feet.
ATTENTION
Maximum equivalent vent lengths are specific to the fuel
type of the water heater. It is impera ve when performing
vent calculatio s the following be taken into consideratio :
Equivalent Vent
Length
x 5
x 2.5
5
x
x 20
x 20
20
5
x 5
x 5
x 15
15
x
40
Total (add up
lines 1 through
12)
for up to 100
Total Equivalent
Length
= 15
= 0
0
=
= 0
= 0
0
0
= 0
= 0
= 15
0
=
= 40
70
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