Mr. Heater MHT 45 - Manual (Page 13)

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Operating Instructions and Owner’s Manual Mr. Heater | Gas-Fired Low-Intensity Infrared Heater
The seams along the length of the piping and the joints
between sections of piping should be sealed to prevent a
potential leakage of flue gas into building. Use 100% RTV
Silicone Rubber Adhesive sealant suitable for 500°F.
6. All portions of the vent pipe shall be supported to prevent from
sagging.
7. When the vent pipe passes through areas where the ambient
temperature is likely to induce condensation of the flue gasses,
the vent pipe should be insulated and a condensation drain
should be provided.
8. The minimum clearance to combustible materials for single-
wall flue pipe shall be 6 inches. This may be reduced when the
combustible material is protected as specified in the National
Fuel Gas Code or the authority having jurisdiction.
9. Single-wall metal pipe shall not originate in any unoccupied attic
or concealed space and shall not pass through any attic, inside
wall or concealed space, or through any floor.
10. A venting system shall terminate at least 3 feet (0.9m) above any
forced air inlet located within 10 feet (3.1m).
b) Vent Termination (Residential Installations)
1. The vent terminal shall terminate above the roof line so that no
discharge opening is less than 2 feet (0.6m) horizontally from
the roof surface. The lowest discharge opening will be no closer
than the minimum height specified in the following table. These
minimum heights may be used provided the vent is not less than
8 feet (2.4m) from any vertical wall or similar obstruction.
a) Be sure that method selected for venting heater complies with all
BASIC FLUE VENTING (Residential Only)
• Venting must be in compliance with the latest edition of the
National Fuel Gas Code (ANSI. Z223.1 latest edition: or the
authority having jurisdiction.
• Uninsulated single-wall metal pipe shall not be used outdoors in
cold climates for venting of these heaters as specified by Section
7.8 of the ANSI Z223.1/NFPA 54 National Fuel Gas Code-latest
edition.
• For the installation of a single-wall metal pipe through an
exterior combustible wall, refer to the latest edition of the
National Fuel Gas Code or the authority having jurisdiction.
• In regions of the country where prevailing winds are consistently
higher than 40 mph, it may be necessary to terminate the vent
system above the roof level.
Other venting references can be found in equipment volume of the
ASHRAE Handbook.
A. SINGLE HEATER VENTING
a) Vertical Through the Roof
NOTE: For residential applications, the heater must
not be connected to a separate chimney,
but must be installed using the venting
system as specified below.
1. When venting the heater to outside of building through a roof,
use 3 inch O.D. single-wall metal pipe. This is to be constructed
of galvanized sheet metal or other approved noncombustible,
corrosion-resistant material as indicated by state and/or local
codes.
2. A vent passing through a combustible roof shall extend through
a 2-inch clearance roof thimble. Double-wall, Type B vent must
be used for the portion of the vent system which passes through
the roof. An approved vent cap (such as Leslie “VersaCap” Type
B) must be attached to the end of the flue.
3. The maximum equivalent length of vent pipe should be carefully
observed. A safety switch in the heater is designed to shut
the heater off before excessive flue restriction causes bad
combustion.
Minimum Equivalent Length = 5 feet of Pipe
Maximum Equivalent Length = 25 feet of Pipe
Use the following correction factors to obtain the equivalent
length:
a) Subtract 15 feet if the run is horizontal.
b) Subtract 10 feet for an approved vent cap.
c) Subtract 10 feet for each elbow beyond 15 feet from the
heater.
d) Subtract 15 feet for each elbow within 15 feet of the heater.
4. Limit the quantity of 90° elbows to two. When vent pipe is in a
horizontal run, it must rise not less than ¼ inch per foot from
the start of the vent system towards the vent terminal.
5. Joints between sections of piping shall be fastened by sheet
metal screws or other approved means.
SINGLE HEATER VENTING
Vent Cap
(Leslie VersaCap)
Type B
2' Min. 2' Min.
(when no wall or
parapet exist) 10'
or less
Flashing
2" Clearance Thimble
Seal joint &
annular space.
4"
Vent
Dia. Total Vent
Height
(5' Min.)
¼ per ft. rise
Lateral
VERTICAL
THROUGH THE ROOF
2' Min.
(when no wall or
parapet exist)
H (Min.)
Not less than 8ft.
2ft. min.
Ver
tical W
all