Ingersoll-Rand ReliaTel, Manual, Page: 106 / 176

106 RT-SVD03L-EN
Operation with a Conventional Thermostat (Constant
Volume)
The ReliaTel ™ module has conventional thermostat
connections as well as zone sensor module
connections. When a conventional thermostat is
controlling the unit, operation differs as follows.
• Supply air tempering feature is not available. If
outdoor air is being introduced through the
equipment, discharge air temperature may be cold
when not actively heating.
• Proportional integral (PI) control is not available.
• Zone sensor diagnostics are only available on the
RTRM module on the J6 terminals, instead of at the
zone sensor in the space.
• Intelligent fall-back is not available. If a failure
occurs in the device controlling the equipment,
operation will cease.
• Heat pump smart recovery and smart staging is not
available. Heat pump operation becomes more
costly unless the generic control being applied can
accomplish this.
• Remote sensing capabilities are not available on
most mechanical thermostats.
• Space Temperature Averaging capabilities are not
available on most mechanical thermostats.
• Built in Night Set Back and Unoccupied Functions
function differently with a conventional mechanical
thermostat.
• A built-in algorithm which allows for automatic
reset of the discharge air temperature while
economizing is not available.
N No otte e:: 27.5 to 50 ton VAV -conventional thermostat
input terminals are inactive.
Figure 65. RTRM - J7
COM
T
X2
Y2
W2
G
W1/0
Y1
R
The terminal strip for attaching the thermostat wires is
located on the RTRM module in the control
compartment. The purpose of each terminal is
discussed in the next section. Customers occasionally
require operation with a conventional thermostat
rather than a zone sensor. In some cases there is a
preference for a specific thermostat model, and in
others there is reluctance to adopt newer technology
that may not be as well understood as conventional
thermostats.
In addition, non-Trane ® Building Controllers typically
provide an interface to HVAC equipment based on a
conventional thermostat interface. Units applied with
this type of controller need to accept conventional
thermostat inputs.
Conventional thermostat signals represent direct calls
for unit functions. In their simplest applications,
thermostat contacts directly control contactors or other
load switching devices. This function provides inputs
for the thermostat signals and processing to enhance
reliability and performance. Compressor protection
and reliability enhancement functions (HPC, LPC,
Minimum On/Off timers, etc.) all operate the same
whether applied with zone sensors or a conventional
thermostat.
Logic is also provided to cause appropriate unit
functions when inappropriate thermostat signals are
provided.
Simultaneous calls for heating and cooling will be
ignored (the unit will not heat or cool). The supply fan
will be turned on with a call for heating or cooling even
if the fan request is not detected.
If the thermostat is immediately changed from a
heating to a cooling call, or vice versa, there will be a
five minute delay before the new call will initiate. For
units with modulating gas heat, see
Figure 66, p.
108 for a flow chart outlining operation with a
conventional thermostat.
N No otte e:: Single Zone VAV units will not work properly
with a 24 volt thermostat. Use of a 24 volt
thermostat with a SZVAV unit is not
recommended.
Table 76. Thermostat signals
R 24VAC power to thermostat
Y1 Call for compressor 1 or first
stage cooling
Y2
Call for compressor 2 or 2nd
stage cooling
G Call for supply fan
W1 Call for heat 1 (for modulating
gas, see
Figure 66, p. 108 )
W2 Call for heat
Heat pump only:
X2 Call for emergency heat