TABLE 1
There are several different types of
elbows that can be used for con-
structing a vent system. The draw-
ings below show the dimensions of
common 1/4 bend and 1/4 bend long
sweep 90 degree elbows from ASTM
3311, Standard Specification for
Drain, Waste and Vent (DWV) Plastic
Fittings Patterns.
A long sweep 1/4 bend 90 degree
(long radius) elbow has an equivalent
length of 5 feet of straight pipe for
eit
her 2 or 3 inch plastic pipe. A stan-
dard 90° elbow has an equivalent
length of 10 feet of pipe. This equiva-
lent length can be used in circum-
stances where it might be necessary
to lengthen the vent at the outside of
the structure, such as in areas with
large accumulations of snow in win-
ter. Table 1 shows the equivalent
lengths of different types of elbows:
With the equivalent length vent
concept a ven
t system can be
used any number of elbows and
length of straight pipe as long as
the maximum equivalent vent
length is not exceeded.
Example:
An RGRC-06 direct vent installation
needs a 31 foot long vent run with 5
elbows and 2 inch pipe.
31 feet of 2 inch pipe = 31
equivalent feet
5 - 1/4 bend long sweep
elbows = 25
equivalent feet
Total = 56
equivalent feet
Since the maximum equivalent vent
length for an RGRC-06 is 60 feet, this
installation is acceptable.
If the same installation tried to use
standard elbows:
31 feet of 2 inch pipe = 31
equivalent feet
5 - standard 90 degree
= 50
equivalent feet
Total = 81
equivalent feet
And this installation is not acceptable
as it exceeds the 60 foot maximum
listed for the RGRC-06 model.
CEMENTING JOINTS
Properly seal all joints in the PVC vent
using the following materials and pro-
cedures:
PVC CLEANER-PRIMER AND
PVC MEDIUM-BODY SOLVENT
CEMENT
IMPORTANT: After cutting pipe,
remove all ragged edges and burrs.
This is important to prevent increase
in pressure
drop throughout the sys-
tem.
1. Cut pipe end square. Chamfer
edge of pipe. Clean fitting socket
and pipe joint area of all dirt,
grease and moisture.
2. After checking pipe and socket
for proper fit, wipe socket and
pipe with cleaner-primer. Apply
a liberal coat of primer to inside
surface of socket and outside of
pipe. READ INSTRUCTIONS
INCLUDED WITH THE PRIMER
FOR PROPER INSTALLATION.
3. Apply a thin coat of c
ement even-
ly in the socket. Quickly apply a
heavy coat of cement to the pipe
end and insert pipe into fitting
with a slight twisting movement
until it bottoms out.
NOTE: Cement must be fluid; if
not, recoat.
4. Hold the pipe in the fitting for 30
seconds to prevent the tapered
socket from pushing the pipe out
of the fitting.
5. Wipe all excess cement from the
joint with a rag. Allow 15 minutes
before handling.
Cure time varies
according to fit, temperature and
humidity.
NOTE: Stir the solvent cement fre-
quently while using. Use a natural
bristle, one inch wide brush or the
applicator supplied with the can.
IMPORTANT: For Proper Installation DO
NOT use solvent cement that has
become curdled, lumpy or thickened.
DO NOT thin. Observe shelf precautions
printed on containers. For application
below 32°F, use only low-t
emperature-
type solvent cement.
For correct installation of the vent pipe,
follow the instructions provided by the
manufacturers of the pipe, primer and
solvent.
EQUIVALENT VENTING
–
ASSIGNING VENT
LENGTH TO ELBOWS
This section applies to venting tables in
both the NON-DIRECT and DIRECT
VENT tables in this book. Vent tables
are provided only in equivalent length
and do not reference elbows or a maxi-
mum number of elbows. Instead, elbows
are assigned a length as described
below. The length determined for each
elbow is subtracted from the max vent
length in the tables to determine how
much
straight vent pipe (in ft) can still be
used.
PIPE & FITTING MATERIAL
ASTM
SPECIFICATION
Schedule 40 PVC (Pipe) D1785
Schedule 40 PVC (Cellular Core Pipe) F891
Schedule 40 PVC (Fittings) D2466
SDR-21PVC (Pipe) D2241
SDR-26 PVC (Pipe) D2241
Schedule 40 ABS Cellular Core DWV (Pipe) F628
Schedule 40 ABS (Pipe) D1527
Schedule 40 ABS (Fittings) D2468
ABS-DWV (Drain Waste & Vent)
(Pipe & Fittings)
D2661
PVC-DWV (Drain Waste & Vent)
(Pipe & Fittings)
D2665
13
EQUI VAL ENT VENTI NG – ASSI GNI NG VENT L ENTGH TO
EL BOWS
T hi s sect i on appl i es to venti ng tables i n both the NON-DI REC T and DI RECT VENT tabl es i n t hi s
book. Vent t abl es ar e pr ovi ded only in equi val ent l ength and do not reference elbows or a maximum
num ber of el bows. I nst ead, el bow s are assi gned a lengt h as descri bed bel ow. The l engt h det ermi ned
f or each el bow i s subtracted from t he max vent length in the tables to determine how much strai ght
v ent pi pe ( i n f t ) can st i l l be used.
T her e ar e sever al di f f er ent t ypes of elbows that can be used for constructi ng a v ent syst em . T he
drawi ngs bel ow show the dimensi ons of common ¼ bend and ¼ bend l ong sweep 90 degree el bow s
f rom ASTM 3311, Standard Speci f i cati on f or Drain, Waste and Vent (DWV) Plastic Fittings
Pat t er ns.
A l ong sweep ¼ bend 90 degree (l ong radi us) el bow has an equivalent l ength of 5 f eet of strai ght
pi pe f or ei ther 2 or 3 i nch pl ast i c pi pe. A st andar d 90° el bow has an equi val ent l ength of 10 f eet of
pi pe. Thi s equi valent l ength can be used i n ci rcumst ances w her e i t mi ght be necessary to lengthen the
v ent at t he out si de of t he structure, such as i n ar eas wi th l arge accumul ati ons of snow i n wi nter.
Table 1 show s the equi val ent l engths of different types of el bows:
T abl e 1
Fitting Type Equivalent L engt h
45° Standard Elbow 5 f eet of pipe
90° Standard Elb ow 1 0 f eet of pip e
45° Long- Sweep Elbow 2-1/2 f eet of pipe
90° Long- Sw eep Elbow 5 f eet of pipe
To Next Page
Need help?
General
