Reznor SFT Unit Installation Manual - Manual (Page 4)

Form RZ -NA-I-SFT, Mfg No. 173474 (Rev 6), Page 3
5. Unit Heater Location
For best results, the heater should be placed with certain rules in mind.
In general, a unit should be located from 8 to 12 feet (2.4 to 3.6 M)
above the floor. Units should always be arranged to blow toward or
along exposed wall surfaces, if possible. Where two or more units are
installed in the same room, a general scheme of air circulation should
be maintained.
Suspended heaters are most effective when located as close to the work-
ing zone as possible, and this fact should be kept in mind when deter-
mining the mounting heights. However, avoid directing the discharged
air directly on the room occupants.
Partitions, columns, counters, or other obstructions should be taken
into consideration when locating the unit heater so that a minimum
quantity of airflow will be deflected by such obstacles.
6. Clearances
This heater must be installed so that the clearances in the table below
are provided for required spacing from combustible construction and
for service and inspection. Clearance to combustibles is defined as the
minimum distance from the heater to a surface or object that is neces-
sary to ensure that a surface temperature of 90°F above the surround-
ing ambient temperature is not exceeded.
Required Clearances - inches (mm)
Model SFT 45, 100, 125, 250,
60, 75 150, 200 300
Top 1 (25) 6 (152) 6 (152)
Flue Connector 6 (152) 6 (152) 6 (152)
Access Panel 20 (508) 24 (610) 24 (610)
Non-Access Side 1 (25) 6 (152) 6 (152)
Bottom* 1 (25) 1 (25) 1 (25)
Rear 18 (457) 18 (457) 24 (610)
*A Model SFT 45, 60, or 75 installed in a residential garage must be
installed with a minimum clearance above the floor of 18 inches
(457mm). Sizes 100-300 are not certified for residential installations.
7. Suspending the Heater
Before suspending the heater, check the supporting structure to be used
to verify that it has sufficient load-carrying capacity to support the
weight of the unit.
Net Weight - lbs and kg
Size 45 60 75 100 125 150 200 250 300
lbs 85 110 120 148 153 216 226 272 294
kg 39 50 54 67 69 98 103 123 133
When the heater is lifted for suspension, support the bottom of the
heater with plywood or other appropriately placed material. If the bot-
tom is not supported, damage could occur.
Determine type of suspension to be used:
•
All Sizes - The heater is equipped with four-point suspension. Two
3/8"-16 threaded nut retainers are located on each side of the heater.
See Dimensions in Paragraph 8 and illustration in Figure 2A.
• Sizes 45, 60, and 75 may be installed with two-point suspension.
Follow the illustrated instructions in Figure 2B, page 4.
• Sizes 45, 60, and 75 may be suspended using an optional ceiling
suspension kit. Refer to Figure 2C. Step-by-step instructions are
included with the option kit.
WARNING: Suspend any size of Model SFT
heater from the threaded nut retainers (Figure
2A). Or, suspend a Size 45, 60, or 75 as illustrated
in Figure 2B or using the Ceiling Suspension Kit
in Figure 2C.
DO NOT suspend any heater from the heater
cabinet panels.
4. High Altitude Operation
If the heater is being installed in an altitude above 2000 ft (610M),
check the rating plate to determine what must be done to prepare the
heater for high altitude operation.
Check the rating plate, determine which circumstance below applies,
and follow the instructions.
• If the altitude range on the rating plate agrees with the altitude at
the site, no further action is required. Proceed with the installation.
• If the altitude range on the rating plate reads "Sea Level" and the
altitude at the site is between 2000 ft and 6000 ft (610M to
1830M), install the heater and follow the instructions in Paragraph
10 to derate by manifold gas pressure adjustment.
• If the altitude range on the rating plate reads "Sea Level" and the
altitude at the site is above 6000 ft (1830M), in addition to adjust-
ing the manifold pressure, it will be necessary to replace the com-
bustion air pressure switch. Order the appropriate switch from the
list below and replace the switch before suspending the heater.
After the heater is installed, follow the instructions in Paragraph
10 to derate by adjusting the manifold gas pressure.
High Altitude (above 6000 ft) Combustion Air Pressure Switches
SFT
P/N Description
45-75 173316 Orange Label, -.55", #PPS10143-2908
100-125 173315 Gray Label, -.35", #PPS10143-2907
150-300 173312 White Label, -.60", #PPS10143-2904
When units are located in the center of the space to be heated, the air
should be discharged toward the exposed walls. In large areas, units
should be located to discharge air along exposed walls with extra units
provided to discharge air in toward the center of the area.
At those points where infiltration of cold air is excessive, such as en-
trance doors and shipping doors, it is desirable to locate the unit so that
it will discharge directly toward the source of cold air from a distance
of 15 to 20 feet (4.5 to 6 M) .
CAUTION: Do not locate the heater where it may be
exposed to water spray, rain, or dripping water.
If the heater is going to be de-rated by adjusting the manifold pressure,
find the label in the owner's envelope. When the adjustment is com-
pleted, fill-in the correct pressure setting with permanent marker and
adhere the label to the heater in a conspicuous location close to the gas
valve.
Figure 1 - Model SFT with Access Panel Open showing
Combustion Air Pressure Switch
(flexible combustion air hose removed
for clarity)
Gas
Valve
Combustion Air
Pressure Switch