Mr. Heater MHU 50 Operating Instructions And Owner's Manual page 6

INSTALLATIONS
HSU compact unit heaters are listed as Category I appliances for
vertical vent installations.
1. 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 50
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
fiberglass 1-1/2# density insulation. If a single wall vent is
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
a common vent with other gas-fired appliances. In common
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.
6
Compact Unit / Utility Heater
VENT TERMINATION ON SINGLE WALL VENT
SINGLE WALL TERMINATION
ROOF FLASHING
ROOF PITCHED
FROM 0" TO 45"
SHALL NOT BE A
CONCEALED SPACE
DOUBLE WALL (TYPE B-1) TERMINATION
ROOF FLASHING
ROOF PITCHED
FROM 0" TO 45"
12" MAX
SEAL JOINT BETWEEN SINGLE WALL VENT
AND "B"VENT AND THE ANNUL AR SPACE OF THE "B" VENT
FIGURE 2
C – HORIZONTAL VENTING – GENERAL
Due to changes to Z83-8 2009 CSA2.6-2009, the use of single
wall B-Vent is no longer permitted as an acceptable material
when venting horizontally, this change covers both residential
and commercial installations. All horizontally vented units
manufactured after July of 2011 must be vented as a Caterory
III Unit/Utility Heater in compliance with UL 1738 & ULS636.
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.
3. Do not terminate vent directly below roof eaves or above
a walkway, or any other area where condensate dripping
may be troublesome and may cause some staining. Avoid
windows where steam may cause fogging or ice buildup.
4. When horizontally vented, minimum clearance for
termination from any door, window, gravity air inlet, gas
or electric meter, regulators, and relief equipment is 4 ft.
(1.2m) for U.S. installations. Refer to NFPA 54/ANSI Z223.1
in the U.S.A. and CSA B149.1 Natural Gas and Propane
Installation Code and .2 in Canada or with authorities having
local jurisdiction. In Canada, vent termination must have a
minimum 6 ft. (1.8 m) horizontal clearance from gas and
electric meters and relief devices as specified in the Canadian
B149.1, Natural Gas Installation Code.
Operating Instructions and Owner's Manual
2" CLEARANCE
THIMBLE
CLEARANCE TO BE AS
SPECIFIED ON TYPE "B"
VENT PIPE