SECTION 7: V
ENTING
13 of 51
Maximum Vent Len
g
ths Table
7.7 Vent Material
Vent material may be single
w
all 26 ga. (minim
u
m)
galvanized steel or eq
u
al thickness stainless steel.
Completely seal all joints, refer to
Page 11, Section
7.2
.
If penetrating a comb
u
stible
w
all or roof, a listed
thimble
w
ith 2" (5 cm) clearance m
u
st be
u
sed.
Where local codes permit, a single section of type
B-1 vent material may be
u
sed at the roof or
w
all
penetration instead of a thimble. Ens
u
re vent
man
u
fact
u
rer's clearance from vent material is
maintained. Seal ann
u
lar space of the type B-1 vent
as
w
ell as all joints in the remaining vent.
7.
8
Replacin
g
an Existin
g
Heater in a Ventin
g
System
When replacing an existing heater in a venting
system, the venting system may not be properly
sized to vent the ne
w
heater. The follo
w
ing steps
m
u
st be follo
w
ed
w
ith each appliance connected to
the venting system placed in operation,
w
hile any
other appliances connected to the venting system
are not in operation.
1. Seal any
u
n
u
sed openings in the venting sys-
tem.
2. Inspect the venting system for proper size and
horizontal pitch, as req
u
ired by the NFPA 54/
ANSI Z223.1 - latest revision, National F
u
el
Gas Code (US) or Standard CSA B149.1
Nat
u
ral Gas and Propane Installation Code
(Canada) and these instr
u
ctions. Determine
that there is no blockage or restriction, leakage,
corrosion and other deficiencies
w
hich co
u
ld
ca
u
se an
u
nsafe condition.
3. Close all b
u
ilding doors and
w
indo
w
s and all
doors bet
w
een the space in
w
hich the
appliance(s) connected to the venting system
are located and other spaces of the b
u
ilding.
T
u
rn on clothes dryers and any exha
u
st fans,
s
u
ch as range hoods and bathroom exha
u
sts
so that they shall operate at maxim
u
m speed.
Do not operate a s
u
mmer exha
u
st fan. Close
fireplace dampers.
4. Follo
w
the lighting instr
u
ctions. Place the
appliance being inspected in operation. Adj
u
st
thermostat so that the appliance
w
ill operate
contin
u
o
u
sly.
5. For any appliance having a draft hood, test for
draft hood appliance spillage at the draft hood
relief opening after five min
u
tes of main b
u
rner
operation. Use the flame of a match or candle.
6. After it has been determined that each
appliance connected to the venting system
properly vents
w
hen tested as o
u
tlined above,
ret
u
rn doors,
w
indo
w
s, exha
u
st fans, fireplace
dampers and any other gas-b
u
rning appliances
to their previo
u
s conditions of
u
se.
7. If improper venting is observed d
u
ring any of
the above tests, the venting system m
u
st be
corrected by a contractor q
u
alified in the
installation and service of gas-fired eq
u
ipment
or yo
u
r local gas s
u
pplier. If the venting m
u
st be
resized,
u
se appropriate tables in (US)
Appendix G of NFPA 54/ANSI Z223.1 - latest
revision, National F
u
el Gas Code (US) or
Standard CSA B149.1 Nat
u
ral Gas and
Propane Installation Code (Canada) to
determine minim
u
m size. All vent corrections
m
u
st be in accordance
w
ith the appropriate
local codes and the NFPA 54/ANSI Z223.1 -
latest revision, National F
u
el Gas Code (US) or
Standard CSA B149.1 Nat
u
ral Gas and
Propane Installation Code (Canada).
Fi
g
ure 6: Vent and Roof Detail
Model UHA[X][S]
150 - 400
# of Elbows
40 ft (12.2 m)
1
35 ft (10.7 m)
2
30 ft (9.1 m)
3
25 ft (7.6 m)
4
20 ft (6.1 m)
5
