Day and Night WCH**4 Manual de instruções de instalação - Página 11

Procurar online ou descarregar pdf Manual de instruções de instalação para Bomba de calor Day and Night WCH**4. Day and Night WCH**4 18 páginas. R?410a split system heat pump

Imprimir página

INSTALLATION INSTRUCTIONS

DEFROST SYSTEM

A. DEFROST THERMOSTAT

The defrost thermostat is factory installed on a short tube

stub extending from the coil end plate. Refer to Figure 11

and confirm that the thermostat is securely fastened in

place on the tube stub.

Figure 11

Defrost Thermostat

FEEDER TUBE

B. DEFROST CONTROL BOARD

The defrost board is a time/temperature control which

includes a field−selectable time period between defrost

cycles of 30, 60, or 90 minutes (quick−connects located

at board edge, factory set at 60 minutes).

Defrost mode is identical to cooling mode except that

outdoor−fan motor stops and second−stage heat is

turned on to continue warming conditioned space.

Initially, the defrost cycle timer starts when the contactor

is energized and a 24 VAC signal is present on the T1

terminal. Then the defrost cycle begins when the defrost

thermostat is closed and the cycle timer times out (30, 60,

90 or minutes).

There are two timers involved in the defrost sequence:

Interval Timer – 30, 60, or 90 minutes, selected by

setting the jumper on the defrost board. Timer is only

active during calls for heating. Timer starts when the

defrost thermostat closes 32° F (0°C ). Timer stops when

a defrost is initiated by the defrost board or when the

defrost thermostat opens 65° F (18° C).

Defrost Timer – 10 minutes, not adjustable. Timer is only

active while the coil is defrosting. Timer starts when the

defrost board initiates a defrost. Timer stops when the

defrost thermostat opens 65° F (18° C) or after timing out

at 10 minutes (whichever comes first).

SPEEDUP pins are provided on the defrost board to help

in troubleshooting without waiting for timers to expire.

Jumpering the SPEEDUP pins causes any active timer to

run very fast (256 times normal speed). Jumpering the

SPEEDUP pins does not by itself initiate any timers, it

only affects timers that are already running or are already

part of the sequence.

To initiate a forced defrost cycle (test cycle), the defrost

thermostat (Figure 11) must be closed.

There are two ways to verify that the defrost thermostat

is closed:

428 01 5302 00

1. Jumper across the DFT terminals on the defrost

board (Figure 12). With this method, the defrost

thermostat is removed from the circuit, and operation

of the defrost thermostat itself will not be observed.

Skip to #3.

2. Use a volt-meter to confirm there is no voltage across

the DFT leads. 24 volts across the SFT terminals

indicates an OPEN defrost thermostat. Zero volts

across the DFT terminals indicates a CLOSED defrost

thermostat.

TUBE STUB

With this method, the operation of the defrost

thermostat can be observed during the test. If the

defrost thermostat is confirmed closed, skip to #3.

If the defrost thermostat is open (24 volts across DFT

COIL

leads) it may be possible to close the defrost thermostat

by forcing a frost buildup on the outdoor coil. Follow

these steps:

DEFROST

THERMOSTAT

3. With unit running in heating mode and the defrost

thermostat closed, the entire defrost sequence can

be sped up for testing by shorting together the

SPEEDUP pins on the defrost board. Use a

flat-headed screwdriver to short the pins together.

4. Hold the SPEEDUP pins shorted together until the

reversing valve shifts.

SPEEDUP reduces whatever time was left on the

interval timer (30/60/90 minutes). In normal operation

the reversing valve will always shift with the SPEEDUP

pins shorted for between 1 and 21 seconds.

5. After shorting the SPEEDUP pins together as

described in #4, the reversing valve will energize

(shift to AC mode), the outdoor fan will stop, the strip

heat will energize, and the coil will begin to defrost.

There are two options for the defrost test:

a. Remove the short from between the SPEEDUP

b. Leave the SPEEDUP pins shorted together for

6. Unit returns to heating mode after defrost sequence.

Reversing valve shifts back, outdoor fan starts up,

and strip heat de-energizes.

R−410A Split System Heat Pump

Turn off power to unit.

Disconnect outdoor fan-motor lead from OF2 on

control board (Figure 12). Tape lead to prevent

grounding.

Restart

unit

heating

accumulation of frost on outdoor coil. Use

volt-meter to confirm there are zero volts across

the DFT leads (thermostat closed).

Turn off power to unit. Replace outdoor fan-motor

lead to OF2 on control board (Figure 12). Restart

the unit in heating mode.

pins immediately after the reversing valve shifts,

and the unit will defrost for a shortened period of

time (something less than 10 minutes). The

defrost will stop when the defrost thermostat

opens (reaches 65° F)(18° C) or when the defrost

timer times out (something less than 10 minutes).

more than 2 seconds after the reversing valve

shifts, and the unit will immediately return to

heating operation (#6 below). Continue to leave

the pins shorted together and the sequence

starts over at #4 above.

mode;

wait

for