Install Instructions
6-583.4
UNIT LOCATION
Location Recommendations
1.  When locating the heater, consider general space and 
heating requirements, availability of gas and electrical 
supply, and proximity to vent locations.
2.  When locating units, it is important to consider that the exhaust 
vent piping must be connected to the outside atmosphere.
3.  Be sure the structural support at the unit location site is 
adequate to support the unit's weight. For proper operation 
the unit must be installed in a level horizontal position.
4.  Do not install units in locations where the flue products 
can be drawn into the adjacent building openings such as 
windows, fresh air intakes, etc.
5.  Be sure that the minimum clearances to combustible 
materials and recommended service clearances are 
maintained. Units are designed for installation with the 
minimum clearances as shown in Table 4.1.
Table 4.1 Clearances
  Unit Side  Clearance To  Recommended
    Combustible Materials  Service Clearance
  Top and Bottom  1"  1"
  Access Side  18"  18"
  Non-Access Side  1"  1"
  Rear  18"  18"
  Vent Connector  4"  4"
6.  Do not install units in locations where the gas ignition system 
is exposed to water spray, rain, or dripping water.
7.  Mounting Height (measured from bottom of unit) at which 
unit heaters are installed is critical. Refer to mounting 
height and heat throw data on page 15 of this manual. The 
maximum mounting height for any unit is that height above 
which the unit will not deliver heated air to the floor. 
Combustion Air Requirements
The National Fuel Gas Code defines an “unconfined space” as 
a space whose volume is greater than 50 cubic feet per 1,000 
Btu/Hr input of the installed appliance(s). A confined space 
is 50 cubic feet or less per 1,000 Btu/Hr input of the installed 
appliance(s).
It is not recommended to install these unit heaters into 
residential confined spaces. This recommendation is due to the 
concern that at some point in time, the combustion air openings 
provided by the installer may become blocked or eliminated by 
the owner, either intentionally or unintentionally. Despite this 
recommendation, if these units are installed into a residential 
confined space, see National Fuel Gas Code ANSI Z223.1 
(NFPA 54) or CSA-B149.1 Installation Code - latest edition, for 
detailed combustion air provisions. The installation must adhere 
to these requirements.
Units installed in confined spaces in industrial/commercial 
installations must be provided with two permanent openings 
- one near the top and one near the bottom of the confined 
space. Each opening should have a free area of not less than 
one square inch per 1,000 Btu/Hr of the total input rating of all 
units in the confined space, freely communicating with interior 
areas that have adequate infiltration from the outside.
For further details on supplying combustion air to a confined 
(tightly sealed) space or unconfined space, see the National Fuel 
Gas Code ANSI Z223.1 (NFPA 54) or CSA-B149.1 Installation 
Code - latest edition.
Turning The Unit 180° (Model Sizes 30-75 Only)
All units are produced at the factory with left-side controls (when 
looking at the unit). If the installation requires the controls to be 
on the right side, all heaters - with the exception of the HD/HDB 
100 and 125 - can be turned over by following the instructions 
below.
• Byturningtheunit180°fromthewayitwasreceivedfrom
the factory, the sides become opposite, but the front and 
back remain in the same relative position. The bottom 
panel now becomes the top panel and vice-versa.
• Removetheaccesspanel,turnit180°,andre-attachitto
the unit so that all the information labels can be read.
• Removethespringloadeddeflectorblades,turnthemover,
replace, and adjust so they are open and in a position to 
direct the heated air down to the floor.
UNIT LOCATION 
4
  dANGER
Appliances must not be installed where they may be exposed 
to a potentially explosive or flammable atmosphere.
IMPORTANT
To prevent premature heat exchanger failure, do not locate   
ANY gas-fired appliances in areas where corrosive vapors   
(i.e. chlorinated, halogenated or acid) are present in the   
atmosphere.
  cAUTION
1.  Clearances to combustible materials are critical. Be sure to   
  follow all listed requirements.
2.  Do not locate units in tightly sealed rooms or small   
  compartments (commonly referred to as confined spaces)  
  without provisions for adequate combustion air and   
  venting. Combustion air must have access to the confined  
  space through a minimum of two permanent openings in   
  the enclosure, at least one near the bottom. They should   
  provide a free area of one square inch per 1,000 BTU/Hr   
  input rating of the unit with a minimum of 100 square   
  inches for each opening, whichever is greater.
3.  Low profile heaters are designed for use in heating applica- 
  tions with ambient temperatures between -40°F and 90°F.
4.  Do not install unit outdoors.
5.  In garages or other sections of aircraft hangars such   
  as offices and shops that communicate with areas used for 
  servicing or storage, keep the bottom of the unit at least 
  7' above the floor unless the unit is properly guarded. 
  In parking garages, the unit must be installed in accordance 
  with the standard for parking structures ANSI/NFPA 88A, 
  and in repair garages the standard for repair garages NFPA  
  #88B. In Canada, installation of heaters in airplane 
  hangars must be in accordance with the requirements 
  of the enforcing authority, and in public garages in 
  accordance with the current CSA-B149 codes.
6.  In aircraft hangars, keep the bottom of the unit at least 10'   
  from the highest surface of the wings or engine enclosure 
  of the highest aircraft housed in the hangars and in accor- 
  dance with the requirements of the enforcing authority 
  and/or NFPA 409 - latest edition.
7.  Installation of units in high humidity or salt water      
  atmospheres will cause accelerated corrosion resulting in a 
  reduction of the normal life of the units.










