Calculating Equivalent Feet - Lochinvar PVL 07575 Installation And Operating Manual

Calculating Equivalent Feet

WATER HEATER VENT SIZE
HEATER INPUT
MODEL (Btu/hr)
75 gal. 76,000
* see Figure 32, "Venting terminations and sizing" and "Vent screen installation".
Equivalent lengths of straight pipe for various elbows using Schedule 40 PVC, CPVC, ABS and polypropylene.
Size Type
3"
90° elbow
4"
3"
45° elbow
4"
Table 2.
COVER PLATE
(OPTIONAL)
TERMINATION
ELBOW
RODENT
SCREEN
(INSTALL INTO
ELBOW)
12 in. MIN. OR ABOVE
Example for calculating equivalent feet.
ANTICIPATED SNOW
Section "A"
LEVEL.
90° elbow
Section B
45° elbow
Section C
45° elbow
Section D
Total Equivalent 34.0 ft.
Based on this example use the (fully open) rodent
GROUND LEVEL
screen for vent length greater than 20 equivalent ft.
(see Figure 32).
Figure 33.
Important: All heaters equipped with the 181°F thermostat
control require that the first 5 ft. of the outlet vent pipe be
installed using the CPVC venting that is supplied with
the heater. If the first elbow is within this 5 ft. length, it
is required to be of CPVC material (field supplied) also.
Use of cellular core PVC (ASTM F891), cellular core
CPVC, or Radel (polyphenylsulfone) in non-metallic
®
venting systems is prohibited.
Important: The exhaust vent piping must be connected
to the blower using the rubber coupling supplied with this
heater. This coupling contains the condensate trap and
is sized for the efficient flow of the exhaust gases. Failure
to use the coupling can result in an unsafe operating
condition and poor heater performance.
100221773_2000189439_Rev. 01
PRESSURE
(Inside SWITCH
Diam.) SETTING
3"
-0.90 in. w.c.
4"
Short Sweep/ Long Sweep/
Short Radius Long Radius
8'
4'
Note: The vent pipe must be supported every 4 ft. . To prevent vibration and sagging, it is recommended to use
isolation pads when attaching straps to floor joists, walls or ceilings. PVC and CPVC vent pipe should be sloped
upwards away from the blower assembly at a pitch of 1/8 in. rise per 4 ft. . Polypropylene vent systems require a
1/4 in. per 1 ft. upward slope to ensure proper drainage.
0.5 ft.
8.0 ft.
1.0 ft.
4.0 ft.
1.5 ft.
4.0 ft.
15.0 ft.
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MAXIMUM EQUIVALENT
VENT LENGTH
50' + termination elbow and
screen*
125' + termination elbow
and screen*
Notes:
1. Use long radius elbows where possible. Minimum
distance between 90º elbows should be 6 in.
5'
wherever possible.
2. Venting systems may use a maximum of five (5)
90° elbows.
2.5'
3. Use proper screen termination (see Figure 32).
STRAP
MINIMUM EQUIVALENT VENT
LENGTH
7' + termination elbow and
screen*
50' + termination elbow and
screen*
45° SHORT
ELBOW
90° SHORT
ELBOW
RUBBER
COUPLING
31