E-4
Compact Unit Heater Venting Kit
Operating Instructions and Owner’s Manual
SHIPPING
The heater vent kit is shipped complete, with all necessary
components. Check the components for damage. The
receiving party should contact the last carrier immediately
if any shipping damage is found.
VENTING
A – GENERAL RECOMMENDATIONS AND
REQUIREMENTS
NOTE:
The vent is a passageway, vertical or nearly so, used to
convey flue gases from an appliance, or its vent connector, to the
outside atmosphere. The vent connector is the pipe or duct that
connects a fuel-gas burning appliance to a vent or chimney.
Unit heaters must be vented in compliance with all local codes
or requirements of the local utility, the current standards of the
(American) National Fuel Gas Code, ANSI Z223.1 or (Canada)
CSA B149.1 Natural Gas and Propane Installation Code, and the
following instructions.
A metal stamped/extruded transition is supplied with this certified
unit. It must not be modified or altered and must be installed
on the outlet of the induced draft blower assembly prior to the
installation of the vent or vent connector. Failure to comply with
this requirement will void the certification of the unit by the
approval agencies. All joints shall be secured with at least two
corrosion resistant screws. All joints must be checked for gas
tightness after installation.
TABLE 2
MAXIMUM VENT LENGTHS
HORIZONTAL VENTS
No. of
ft
m
Elbows
1
25
7.6
2
20
6.1
3
15
4.6
4
10
3.0
5
5
1.5
Maximum length of vent connector not to exceed 30 ft. (9.1m).
B – VERTICAL VENTS USING METAL VENT
PIPE – COMMERCIAL AND RESIDENTIAL
INSTALLATIONS
MHU/HSU compact unit heaters are listed as Category I
appliances for vertical vent installations.
1. MHU/HSU unit heaters are to be used with NFPA- or ANSI-
approved chimneys, U.L. listed type B-1 gas vents, single
wall metal pipe, or listed chimney lining system for gas
venting where applicable, as well as the modifications and
limitations listed in
Figure 2
. Seal single wall vent material
according to the section
A - General Recommendations
and Requirements.
2. The vent connector shall be 3” (76mm) diameter on 45 units.
In all cases, a flue transition piece (supplied) is required to
fit over the outlet of the induced draft assembly on the
appliance.
3. Keep the vent connector runs as short as possible with
a minimum number of elbows. Refer to the (American)
National Fuel Gas Code ANSI Z223.1 or (Canada) CSA B149.1
Natural Gas and Propane Installation Code for maximum
vent and vent connector lengths. Horizontal run of the vent
connector from the induced draft blower to the chimney/vent
cannot exceed the values in
table 2
.
4. When the length of a single wall vent, including elbows,
exceeds 5 feet (1.5m), the vent shall be insulated along
its entire length with a minimum of 1/2” thick foil faced
used in an unheated area it shall be insulated. Failure to do
so will result in condensation of flue gases.
5. The unit may be vented vertically as a single appliance or as
venting situations, vent connectors for other appliances
must maintain a 4” (100mm) vertical separation between
the vent connectors. Refer to common venting tables in the
(American) National Fuel Gas Code ANSI Z223.1 or (Canada)
CSA B149.1 Natural Gas and Propane Installation Code for
proper vent size.
6. Clearance to combustible material is 6” (152mm) for single
wall vent material except where a listed clearance thimble is
used. Clearance to combustible material for type B-1 vent or
factory-built chimney is per manufacturer’s instructions.
7. The vent connector shall be supported without any dips or
sags. Vertical vents shall be supported in accordance with
their listing and manufacturers’ instructions. All horizontal
vent connector runs shall have a slope up to the vertical vent
of at least 1/4” per foot (1mm per 50mm).
8. All vertical type B-1 vents, single wall vents, or listed chimney
lining system must be terminated with a listed vent cap or
listed roof assembly.
9. The vent must extend at least 3’ (1m) above the highest point
where it passes through a roof of a building and at least 2’
(0.6m) higher than any part of a building within a horizontal
distance of 10’ (3.05m) unless otherwise specified by the
(American) National Fuel Gas Code, ANSI Z223.1 or (Canada)
CAN/CGA-B149 Installation Code. The vent must extend at
least 5’ (1.6m) above the highest connected equipment flue
collar.
C – HORIZONTAL VENTING – GENERAL
Common venting is not allowed when horizontally venting the unit
heater.
The minimum horizontal vent length is three feet (914mm).
1. If possible, do not terminate the horizontal vent through a
wall that is exposed to prevailing wind. Exposure to excessive
winds can affect unit performance.
2. Vent termination must be free from obstructions and at least
12” (306mm) above grade level and maximum snow height.
