Mr. Heater MHU 50 Operating Instructions And Owner's Manual page 7

5. Vent termination must be a minimum of 4' (1.2m) below
or 4' (1.2m) horizontally from any soffit vent or under-eave
vent.
6. Vent must be a minimum of 6' from an inside corner formed
by two exterior walls. If possible, leave a 10' clearance.
7. Vent termination must be a minimum of 10' (3m) from any
forced air inlet (includes fresh air inlet for other appliances,
such as a dryer).
8. When termination is routed through an exterior combustible
wall the vent must be supported using a listed clearance
thimble. Seal the connection between the single wall and
double wall pipes and the annular space of the double wall
pipe as shown in figure 2. Inside edge of vent termination
tee must be at least 12 inches from outside wall as shown in
figure 3.
9. For horizontal venting, the vent pipe shall be supported with
hangers no more than 3ft. (1m) apart to prevent movement
after installation.
D – HORIZONTAL VENTING – COMMERCIAL
1. Horizontal commercial installations are for buildings which
are not attached to living spaces. The vent may be single wall
vent material installed according to the sections
Venting A - General Recommendations and
Requirements and C - Horizontal Venting General and D -
Horizontal Venting - Commercial. Refer to figure 3.
2. The vent pipe diameter for horizontal commercial
installations shall be 4" (76mm) on 50 units. Because of this
a transition piece has been supplied and is already attached
to your heater. Refer to figure 4
CATEGORY III VENT ACCORDING TO THESE INSTALLATION INSTRUCTIONS.
FLUE TRANSITION
(PROVIDED)
NOTE - MINIMUM HORIZONTAL LENGTH 3 FT. (914MM),
NOT INCLUDING CAP FOR TERMINATION. REFER TO TABLE
2 FOR MAXIMUM LENGTH AND NUMBER OF ELBOWS.
CONDENSATE DRAIN THROUGH TEE PIPE AND DRAIN LOOP
UPWARD SLOPE ON HORIZONTAL VENT-COMMERCIAL INSTALLATION
SLOPE: + 1/4 INCH FOR 1 FOOT RUN MINIMUM.
TRAP (TO CONDENSATE DRAIN)
COMMON VENTING NOT ALLOWED WHEN HORIZONTALLY VENTING THE UNIT / UTILITY HEATER
Compact Unit / Utility Heater
3. Refer to table 2 for maximum vent connector lengths.
4. Select a wall termination point that will maintain 1/4¼" rise
per foot slope of horizontal run of vent pipe.
5. For upward sloped vent a condensate tee and drain must
be installed within the first 5' (1.5m) from the unit heater
to protect the appliance. If a flexible condensate drain line
is used, the drain line must include a loop entering the
structure. If the unit is shut down for an extended period of
time and will be exposed to sub-freezing temperatures, the
condensate may freeze.
E – HORIZONTAL VENTING – RESIDENTIAL
1. For horizontal residential installations these units are
certified as Category III appliances. Venting A - General
Recommendations and Requirements and C - Horizontal
Venting General and E - Horizontal Venting - Residential.
Refer to figure 6.
2. The vent pipe diameter for horizontal residential installations
shall be 4" (100mm) on 50 and 80 units. A standard vent
transition is required at unit in addition to the transition
supplied with the unit.
3. The maximum vent length is 5' (1.5m) plus one 90-degree
elbow. The minimum length is 3'(.91m).
4. The vent must maintain a 1/4¼" rise per foot of slope
upwards toward the termination.
FLUE TRANSITION (ATTACHED)
LISTED THIMBLE
THROUGH COMBUSTIBLE
WALL
DRAIN LOOP WITH WATER
FIGURE 3
7
Operating Instructions and Owner's Manual
FIGURE 4
12 INCHES MIN.
(30.5 CM)
EXHAUST VENT
TERMINATION TEE
12" (30.5 CM)
MINIMUM ABOVE ALL
HIGHEST SNOWFALL