User Guide

Infrared Heater Selection Procedure – Additional Selection Considerations
10 9-200.6
Wiring Multiple Low Voltage Heaters to a Single Thermostat
When using a single thermostat to control multiple heaters with
low voltage (24V) control, relays are required per the National
Electric Code to isolate the control transformers on individual
heaters so that the secondary side, or low voltage side of
control transformers are not wired in parallel.
Please see Literature #9-410, latest revision for additional
details.
Humidistat
For unvented heater applications, there are minimum
ventilation requirements. These requirements were briefly
discussed in the previous section. However, with ventilation
requirements met, there still may be excessive humidity in the
space. A humidistat should be considered to activate
additional exhaust fans if humidity rises.
Thermostat Location
It is important to place thermostats out of the line-of-sight from
the heaters. If placed in the line-of-sight with the heaters, they
will read erroneous temperatures, not actual air temperature.
In spot or area heating applications, it is common to use On/Off
switches in lieu of thermostats, as the intent is to cause
comfort from the radiant infrared, not from heated air.
Contaminated Atmospheres
Infrared heaters should never be used in areas where
hazardous or explosive materials exist. They also should not
be used in areas where chlorinated, halogenated, or acid
vapors are present. For dirty environments that are not
classified as an area requiring explosion proof equipment, low-
intensity units can be used with clean outside combustion air
ducted to the units. However, the unit is not considered to be
separated combustion or explosion proof.
Negative Pressure in Space
High intensity units are generally tolerant of negative pressure
in the space being heated since the units operate unvented.
Low intensity units are generally tolerant of slight negative
pressure in the space being heated since the units are power
exhausted. However, when the negative pressure may be
more significant, low intensity units are advantageous as
outside combustion air can be ducted directly to the unit so that
the intake and exhaust are both at atmospheric pressure.
Outdoor Applications
Modine offers a line of low-intensity units that are suitable for
outdoor applications. It is important to note that perceived
performance will not be the same for an outdoor application as
for an indoor application. Outdoor conditions can have a
considerable effect on how the unit is perceived to be
operating. The following are several examples:
 Considerable wind will cause a greater cooling effect on
people, thus requiring more heater input.
 If mounted above dirt floors, re-radiation typically seen
from a concrete slab will be virtually non-existent, as the
dirt floor will simply absorb the heat and conduct it away
from the surface, into the Earth.
Duration of Operation
For spot or area heating operations, the heaters are normally
operating only while there are people in the area required to be
heated. This is often accomplished with an On/Off switch.
For total building heating, the heaters will cycle to maintain the
temperature. Often, upon startup the heaters will run
continuously for days as the building structure (floors, walls,
equipment, etc.) rises to a steady state as required to maintain
comfort temperature levels. Once the space has been
effectively heated, the units will cycle normally.
It is important to note that for total building heating, during
unoccupied periods, the heaters should not be turned off and
the use of setback temperature minimized. As stated in the
previous paragraph, it can take days for the building structure
to become heated to properly maintain a comfortable space
temperature.
Low-Intensity Tube System Expansion
Tube systems can expand/contract by 1-6” based on heating
and cooling cycles of operation. This must be accounted for in
the installation to avoid alignment problems. The following are
remedies, that when combined, will allow proper operation
during expansion/contraction:
 Chain-mounting (minimum length per I&S Manual)
 Flexible gas connectors
 Tighten tube clamps to 50 ft-lb.
 Overlap reflectors by 4”, every other joint screwed
Accessories
The following accessories can simplify or improve the
installation/layout of the infrared heating solution:
 Chain mounting sets allow quick and easy hanging of the
heaters. Since low-intensity tube lengths change during
operation due to expansion and contraction, chain
mounting is required.
 Stainless steel flexible gas connectors, when allowed by
local codes, allows for expansion and contraction of the
heater without placing stress on the gas supply piping.
 Reflector extensions (low-intensity only) can be used to
concentrate radiant energy in a smaller area or to direct
heat away from a wall if mounted at 0° next to a wall.
With all the infrared heater choices that Modine offers, there is
great flexibility in design options. Table 11.1 on the following
page summarizes some common application considerations for
making a choice between different infrared heater types.