Reznor Q6SP Unit Installation Manual User Manual

Page 9

5. Install the correct thermostat housing to subbase.
6. Refer to thermostat instruction sheet for complete

detailed mounting and operating information.

Defrost cycle timer

The defrost cycle timer controls the time interval of the hot

gas defrost after the defrost sensor closes. It is located in

the lower left corner of the defrost control board on the of

the control panel. Three interval settings are available: 30,

60, and 90 minutes. Time setting selection is dependent

on the climate where the unit is being installed. To set the

cycle timer, place the timing pin on the defrost control

board to the desired time interval post.

notE: All units

are shipped from the factory with the default time setting

of 30 minutes. Longer settings are recommended for drier

climate areas and shorter time intervals are recommended

for moist climate areas.

Defrost control Board
Operational Information
• Terminals

r - rc must have 24±V present between

them in order for the time delay and defrost sequences
to be operational.

• Jumpering the

t2 - DFt test pins will communicate

to the board that the defrost T-stat is closed (if the

compressor is running). The defrost thermostat tells
the board whether a defrost cycle needs to be started
or terminated.

notE: The defrost T-stat is closed at

32° F or below and is open at 68° F or above, but it’s
state is unknown if the temperature is between 32° F
and 68° F.

• With the DFT closed, the unit will run for 30/60/90

minutes in heat mode and then defrost the outdoor
coil. The defrost will turn off the outdoor fan, turn on
the compressor and raise the coil temperature to 68°
F. This will open the DFT and terminate the defrost. If
the DFT does not open the defrost will end after 10
minutes.

• Jumpering the

tEst terminal to the c (common)

terminal (While the compressor is in heat mode), will
over-ride the defrost boarrd and initiate a faster defrost
test in 5, 10 or 15 seconds as determined by the 30, 60
or 90 minute defrost pin settings. (The factory setting
is 30 minutes).
– This will bypass the compressor off delay when the

unit goes into defrost test and if left in defrost test, the
delay will be bypassed when the test is terminated
by the processor.

notE: If the jumper is removed

before the test is over, the processor will perform the
remainder of a normal defrost. See step 2 above.

• The delay/no-delay pin concerns compressor operation

during defrosts. To switch from no-delay to delay, remove

the pin from the

no - delay pin location and shift it to

the

delay pin location. The default setting is delay.

– Reciprocating compressors should only use this

setting in conjunction with an approved hard start

kit.

– Scroll compressors that have noise issues while

going into or coming out of defrost should use this

30 second delay to reduce the defrost noise.

– Manually initiating a defrost will cause the compressor

to run continually when entering defrost.

Normal defrost operation

To test normal defrost operation when the temperature is

above 35° F, jumper

r to DFt on the 624656 board and

allow the unit to run for 30 minutes. Defrost will continue

until the

r to DFt jumper is removed or for 10 minutes.

Remove the jumper.

The 5 minute time delay feature can be shortened 1 time

to 1 second by jumping the

test to c terminal. Remove

the jumper and repeat as desired.
notE: If jumper is left on the test to common pins

permanently, the defrost cycle will become inoperable.

Defrost Test Procedure
1. Jumper

t2 to DFt at the test terminals.

2. With unit running in heat mode, short the

tEst terminal

to the common terminal near it. This will speed up the
board and cause it to enter defrost mode in 5/10/15
seconds depending on the defrost time selection.
Compressor delay will not function during speed-up.

Figure 8. typical connections -

2 stage cool/3 stage Heat t-stat

Indoor Thermostat

Sub-Base

Unit Low Voltage

Terminal

24 V Hot

Stage 3
Heat
(Optional)

Blower

Emer. Heat

Stage 2
Heat/Cool

Stage 1
Heat/Cool

24 V Com

Rev. Valve

‡

t-stat Wire

Gauge

recommended t-stat Wire

length - Ft. (unit to t-stat)

18 Ga.

0 - 60

16 Ga.

61 - 130

Field Supplied Wiring - Use Solid Class II Copper Wire.

‡ “O” - Energized when thermostat system is in “Cool”

Mode.

notE: If thermostat has one combined “O/B” Terminal

and

an Economizer is installed, see Economizer

Installation Instructions for unit wiring change for proper

operation.