Mr. Heater MHU 50 Operating Instructions And Owner's Manual page 8

INDUCED DRAFT BLOWER
CATEGORY III VENT ACCORDING TO THESE INSTALLATION
INSTRUCTIONS.
SLOPED: + 1/4 INCH FOR 1 FOOT RUN MINIMUM.
NOTE - MINIMUM HORIZONTAL LENGTH 3FT. (914MM), NOT
INCLUDING CAP FOR TERMINATION.
MAXIMUM HORIZONTAL LENGTH 5FT. (1.5M) PLUS ONE
90-DEGREE ELBOW.
COMMON VENTING NOT ALLOWED WHEN HORIZONTALLY VENTING THE UNIT / UTILITY HEATER.
F – VENTING USING A MASONRY CHIMNEY
The following additional requirements apply when a lined
masonry chimney is being used to vent the compact unit / utility
heater.
1. Masonry chimneys used to vent Category I units heaters
must be either tile-lined or lined with a listed metal lining
system or dedicated gas vent. Unlined masonry chimneys are
prohibited. A category I appliance must never be connected
to a chimney that is servicing a solid fuel appliance. If a
fireplace chimney flue is used to vent this appliance, the
fireplace opening must be permanently sealed.
2. A fan assisted unit heater may be commonly vented into an
existing lined masonry chimney provided:
•
The chimney is currently serving at least one draft-hood
equipped appliance.
•
The vent connector and chimney are sized in accordance
with venting tables in the (American) National Fuel Gas
Code ANSI Z223.1 or (Canada) CSA B149.1 Natural Gas
and Propane Installation Code.
IMPORTANT Single appliance venting of a fan assisted unit
heater into a tile lined masonry chimney (interior or outside wall)
is prohibited. The chimney must first be lined with either type B-1
vent or an insulated single wall flexible vent lining system, sized
in accordance with venting tables in the (American) National Fuel
Gas Code ANSI Z223.1 or (Canada) CSA B149.1 Natural Gas and
Propane Installation Code.
3. A type B-1 vent or masonry chimney liner shall terminate
above the roof surface with a listed cap or a listed roof
assembly in accordance with the terms of their respective
listings and the vent manufacturer's instructions.
4. Do not install a manual damper, barometric draft regulator,
or flue restrictor between the unit heater and the chimney.
5. If type B-1 double-wall vent is used inside a chimney, no
other appliance can be vented into the chimney. Outer wall
of type B-1 vent pipe must not be exposed to flue products.
6. Insulation for the flexible vent pipe must be an encapsulated
fiberglass sleeve recommended by the flexible vent pipe
manufacturer.
HORIZONTAL VENTING - RESIDENTIAL INSTALLATION
UPWARD SLOPE
FLUE TRANSITION
(PROVIDED)
LISTED THIMBLE THROUGH
COMBUSTION WALL
FIGURE 6
Compact Unit / Utility Heater
12 INCHES
MIN. (30.5CM)
7. The space between liner and chimney wall should NOT
be insulated with puffed mica or any other loose granular
insulating material.
8. If type B-1 vent or an insulated flexible vent pipe cannot be
used as liners, the chimney must be rebuilt to accommodate
one of these methods or some alternate approved method
must be found to vent the appliance. When inspection
reveals that an existing chimney is not safe for the intended
purpose, it shall be rebuilt to conform to nationally
recognized standards, lined or relined with suitable materials
or replaced with a gas vent or chimney suitable for venting
unit heaters. The chimney passageway must be checked
periodically to ensure that it is clear and free of obstructions.
G – REMOVAL OF UNIT FROM COMMON
VENT
In the event that an existing unit heater is removed from a
venting system commonly run with separate gas appliances,
the venting system is likely to be too large to properly vent the
remaining attached appliances. The following test should be
conducted while each appliance is in operation and the other
appliances are not in operation, yet remain connected to the
common venting system. If the venting system has been installed
improperly, the system must be corrected.
1. Seal any unused openings in the common venting system.
2. Visually inspect the venting system for proper size and
horizontal pitch. Determine there is no blockage or
restriction, leakage, corrosion, or other deficiencies which
could cause an unsafe condition.
3. If practical close all building doors and windows and all
doors between the space in which the appliances remaining
connected to the common venting system are located and
other spaces of the building. Turn on clothes dryers and
any appliances not connected to the common venting
system. Turn on any exhaust fans, such as range hoods
and bathroom exhausts, so they will operate at maximum
speed. Do not operate a summer exhaust fan. Close fireplace
dampers.
4. Follow the lighting instructions. Place the appliance being
8
Operating Instructions and Owner's Manual
VENT TERMINATION CAP