10
1.6 Vent Requirements and Details
1.6.1 Unvented units
Heaters may be installed without a vent
providing the governing building codes are met
and consideration is properly given to
possibilities of condensation on cold surfaces.
Installation
shall
meet
the
following
requirements when unvented:
Natural or mechanical means shall be
provided to supply and exhaust at least 4
CFM per 1000 BTU per hour input of
installed heaters.
Combustion gasses shall not impinge on
combustible materials.
1.6.2 Vertical venting
The heater can be installed with a vertical vent.
All vent piping should be adequately supported
from the building structure and terminated with
an
approved
terminal.
The
maximum
recommended vent length is 25ft (7.6m) with
a maximum of two elbows
. All connections
should be properly sealed. Refer to fig 7a.
1.6.3 Horizontal venting
Individual units can be vented horizontally
through side walls. Recommended terminals
are Part Numbers V0700 for 4” and V0800 for
6”.
Distances from adjacent public walkways,
adjacent buildings, openable windows and
building openings, consistent with the
National
Fuel Gas Code, ANSI Z223.1/NFPA 54
or the
Natural Gas and Propane Installation Code,
CSA B149.1.
Maximum length of vent is 25ft (7.6m) with two
- 90° elbows.
Runs of 12ft (3.6m) or shorter can use
4” (101mm) dia vent. Runs over 12ft (3.6m)
should use 6” (152mm) vent pipe.
Any portion of vent that passes through a
combustible wall must be insulated, or use an
approved insulating thimble.
Standard vent terminals must extend at least
6” (152mm) from the wall and at least
24” (609mm) from any combustible overhang.
This protects the building material from
degradation by the vent gasses.
Vent joints should be sealed and secured
according
to
the
vent
manufacturers
instructions. Should condensation occur the
vent should be shortened or insulated.
The terminal should be at least 3ft (0.91m) away
from any air intake to the building.
If the heater is equipped with ducted combustion
air, the vent terminal must be at least 3ft
(0.91m) away from the air inlet and located
higher than the inlet.
The vent terminal must be installed at a suitable
height above the ground to prevent blockage by
snow.
1.7
Fresh Air Intake
Whenever the heater is installed in locations
where airborne dust or other pollutants are
present, a fresh air supply should be ducted to
the burner.
A fresh air duct of 4”(101mm) dia. should be
installed from the fresh air to the air intake
connection on the fan housing. A flexible
jointing piece should be installed at the fan
connection with hose clamps to facilitate
expansion and contraction.
The maximum recommended length air duct is
25ft (7.6m) and the maximum number of elbows
is two. The minimum length is 18” (456mm).
The location of the fresh air duct inlet must be
where it will receive dust free clean air. An inlet
cap with bird screen must be fitted at the inlet of
the duct. If the duct inlet is located above the
roof the underside of the inlet terminal must be
at least 2ft (0.61m) above roof level and at least
10” (254mm) above any projection on the roof
within 7ft (2.1m) of the inlet. Intake pipe, fittings
and sealant are not furnished by the
manufacturer. Refer fig 7c & d.
