User Guide

Infrared Heater Selection Procedure – Spot Heating
6 9-200.6
Application/Intended Operation of the System
Infrared systems can serve three basic applications:
 Spot heating – Used for heating only small areas, such
as a loading dock or a single person work cell. Excellent
application for infrared.
 Partial building heating – Used to heat sections of a
building such as an assembly line or office section
located in an open area of a warehouse. Excellent
application for infrared.
 Total building heating – Used to heat the entire
building. This is a fair application for infrared, but other
equipment should also be considered as an alternate.
The following section will provide specific background
information necessary to satisfy each of these applications.
Spot Heating
Spot heating is used for individual workers who require the
replacement of body heat loss where heating the surrounding
area with forced air heat would not be practical. Infrared heat
is well suited for this application, as the objects (people) would
be heated and not the surrounding air. The heat required for
individual comfort varies with environmental, physiological, and
even psychological variables. Activity level, room temperature,
relative air movement, humidity, and clothing all contribute to
the comfort or discomfort of an individual. It is also
psychological since one person’s perception of comfort is
different than another person’s perception.
There are various engineering principles and calculations that
can be used to derive appropriate ratings for comfort spot
heating. However, there is still the psychological factor that
differs between people that cannot be easily accounted for in
equations. In lieu of working through complex formulas, the
following table can be used to approximate the model number
required to meet the conditions of the application. For spot
heating, high intensity heaters are the best choice. It is
preferable to use two heaters for heating people to ensure both
the front and back sides are comfortable. If it is impractical to
use two heaters, it is usually advisable to use one heater of the
next higher model at an increased mounting height, provided
mounting height restrictions do not eliminate this option.
Table 6.1 shows three different ambient conditions; Cold/Drafty
Air, Average/Calm Air, and Warm/Still Air. The occupant of the
space should make the determination of the ambient
conditions, based on personal perception. Once ambient
conditions are determined, heater ratings can be determined
based on the available mounting height. For areas requiring
larger coverage, units with higher ratings can be used,
provided the available mounting heights are adequate. Note
that the table assumes a 30° mounting angle. Mounting angles
less than 30° are not advisable since the heater would then
need to be mounted more directly overhead of the person. In
this situation, excessive infrared energy would be directed at
the head of the person, causing discomfort and uneven heating
over the surface of his/her body.
Table 6.1 – Spot Heater Selection Table
Model Ambient Conditions Recommended Mounting Height Recommended Horizontal Distance to Person Approximate Area of Coverage
IHR 30
Cold/Drafty Air 8'-10' 4'-5' 10' x 10'
Average 10'-12' 5'-6' 12' x 12'
Warm/Still Air 12'-14' 6'-7' 14' x 14'
IHR 60
Cold/Drafty Air 12'-14' 6'-7' 16' x 16'
Average 14'-16' 7'-8' 18' x 18'
Warm/Still Air 16'-20' 8'-9' 20' x 20'
IHR90
Cold/Drafty Air 18'-20' 9'-10' 20' x 20'
Average 20'-22' 10'-11' 24' x 24'
Warm/Still Air 22'-26' 11'-12' 28' x 28'
IHR130
Cold/Drafty Air 22'-26' 11'-12' 26' x 26'
Average 26'-30' 12'-13' 30' x 30'
Warm/Still Air 30'-36' 13'-14' 35' x 35'
IHR160
Cold/Drafty Air 24'-28' 12'-14' 28' x 28'
Average 28'-32' 14'-16' 35' x 35''
Warm/Still Air 32'-36' 16'-20' 40' x 40'
 Note that these are recommended values only and may need to be
adjusted to meet requirements of the actual installation. A 30°
mounting angle is required.
Figure 6.1 – Typical Spot Heater Mounting
(Single Heater Shown)
Low Intensity Unit for Spot Heating
While high intensity units are the best option for spot heating
applications, low intensity units can be used but should be kept
to 20 or 30 foot long tube systems in a U-tube configuration.
Mounting angle should be 45°, ideally with two units, one on
each side of the person.
30°