RT-SVX23D-EN 41
Start-Up
Verifying Proper Air Flow (Units with Two Speed Direct Drive Indoor Fan)
Much of the systems performance and reliability is closely associated with, and dependent upon
having the proper airflow supplied both to the space that is being conditioned and across the
evaporator coil.
The indoor fan motor is factory wired to operate on low speed in the cooling and heating mode.
It can be rewired for high speed operation should the application require it. Refer to the wiring
diagram that shipped in the unit.
The indoor fan motors are specifically designed to operate within the BHP parameters listed in the
fan performance tables of the unit Service Facts. By understanding that these motors will safely
work within these conditions, before an oversized motor is required, will allow the air distribution
system to be set up properly and diagnostics enhanced should a problem occur.
When verifying direct drive fan performance, the tables must be used somewhat differently than
those of belt driven fans. Fan performance diagnostics can be easily recognized when these tables
are used correctly.
Before starting the SERVICE TEST, set the minimum position setpoint for the economizer to 0
percent using the setpoint potentiometer located on the Economizer Control (ECA), if applicable.
ReliaTel Control
Using the Service Test Guide in Tab le 7 , momentarily jump across the Test 1 & Test 2 terminals on
LTB1 one time to start the Minimum Ventilation Test.
With the fan operating properly, determine the total system external static pressure (inches w.c.)
by;
1. Measuring the supply and return duct static pressure,
2. Using the accessory pressure drop table in the Service Facts, calculate the total static pressure
drop for all of the accessories installed on the unit; i.e., curb, economizer, etc.
Note: Static pressure is based on desired CFM and may not be actual static pressure.
Table 7. Service test guide for component operation
Test Step Mode Fan
Econ (Note
2) Comp1 Comp 2Heat 1Heat 2Ohms
1FanOn
Minimum
Position
Setpoint 0%
Off Off Off Off 2.2K
Minimum
Ventilation
On Selectable Off Off Off Off
2
Economizer Test
Open
On Open Off Off Off Off 3.3K
3 Cool Stage 1 On
Minimum
Position
On (Note 1) Off Off Off 4.7K
4 (Note 3) Cool Stage 2 On
Minimum
Position
On (Note 1) On Off Off 6.8K
5 (Note 3) Reheat On Minimum On On Off Off 33K
6 (Note 3) Heat Stage 1 On Minimum Off Off On Off 10K
7 (Note 3) Heat Stage 2 On Minimum Off Off On On 15K
Notes:
1. The condenser fans will operate any time a compressor is "On“ providing the outdoor air temperatures are within the operating val-
ues.
2. The exhaust fan will turn on anytime the economizer damper position is equal to or greater than the exhaust fan setpoint.
3. Steps for optional accessories and non-applicable modes in unit will be skipped.
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