Page 53
CHP16/20 P VOLTAGE SEQUENCE OF OPERATION
Operation Sequence
Cooling:
1- Line voltage energizes transformer T1. Transformer
T1 provides 24VAC power to all unit controls and therĆ
mostat.
2- Latch relay K6 controls operation of reversing valve L1
during normal operartion (contacts K10-2 control reĆ
versing valve during defrost). Latch relay K6 operates
as follows:
a- 24VAC from Y1 cooling demand applied to K6
SET" coil closes K6-1 and switches K6-2 (contacts 6-8
close and 6-4open). Contacts 6 and 8 remains closed
when power is removed.
b- 24VAC from W1 heating demand applied to K6 REĆ
SET" coil opens K6-1 and switches K6-2 (contacts 6-8
open and 6-4 close). K6-1 and K6-2 remain in this posiĆ
tion when power is removed.
3- Cooling demand energizes Y1 and G in the thermostat.
Y1 energizes K6 relay SET" coil. K6-1 and K6-2 immeĆ
diately switch. G energizes indoor blower relay K3.
4- When K6-1 closes, reversing valve L1 is energized.
When K6-2 switches (contacts 6-8 close), contactor K1
is energized.
5- K1-1 closes to energize compressor and the condensĆ
er fan.
CHP16-024/-030 models only (reciprocating compresĆ
sor)-At compressor start up, terminal S is powered by
start capacitor C7.
6- CHP16-024/030 only-When compressor nears full
speed potential relay K31 is energized and start capacĆ
itor C7 is taken out of circuit. K31 remains energized
during compressor operation. Run side of dual capaciĆ
tor C12 remains in the circuit between terminals R ands
S during all compressor operation.
7- K3-2 switches to energize the blower on high speed.
K3-1 switches to power the economizer (if equipped).
Dampers open to minimum position.
Heating:
8- 1st. stage heating demand energizes W1 in the therĆ
mostat. W1 energizes transfer relay K8 and K6 relay
RESET" coil. K6-1, K6-2 and K8-1 all switch immediĆ
ately.
9- When K8-1 switches, indoor blower relay K3 is enerĆ
gized.
10-When K6-1 opens, reversing valve L1 is de-energized.
When K6-2 switches (terminals 6-8 open and 6-4
close), compressor contactor K1 and de-frost board
CMC1 are energized.
11- K1-1 closes to energize the compressor and condensĆ
er fan.
CHP16-024/030 only- As compressor gains speed,
compressor terminal S is powered by start capacitor
C7.
12-CHP16-024/030 only-At compressor start up, potential
relay K31 is energized and start capacitor C7 is taken
out of circuit. K31 remains energized during compresĆ
sor operation. Run side of dual capacitor C12 remains
in the circuit between terminals R ands S during all
compressor operation.
13-K3-2 switches to energize the blower on high speed.
K3-1 switches to power the economizer (if equipped).
Dampers open to minimum position.
14-Additional heating demand W2 is directed to optional
electric heat (not shown).
Defrost Mode:
15-During heating operation, when outdoor coil temperaĆ
ture drops below 35ºF 4ºF, the defrost thermostat
closes.
16-After 30, 60 or 90 minutes of heating demand (dependĆ
ing on how the conrtrol is pre-set) CMC1 checks for deĆ
frost demand by closing a set of relay contacts conĆ
nected to terminal OUT. Terminal OUT remains enĆ
abled for 14 1 minutes. If defrost temperature therĆ
mostat S6 is closed when terminal OUT is enabled, deĆ
frost relay K4 and outdoor fan relay K10 are allowed to
energize and defrost begins.
17-When K4 energizes, K4-1 opens and K4-2 and K4-3
close.
18-When K10 energizes, K10-1 and K10-2 immediatley
switch.
19-When K4-1 opens internal timer is reset to zero.
20-When K4-2 closes, W1 is shunted to W2 to energize
optional electric heat.
21-When K4-3 closes, defrost relay K4 and outdoor fan
relay K10 are latched in until defrost terminates.
22-When K10-1 opens, the outdoor fan is de-energized.
23-When K10-2 switches, reversing valve L1 is energized.
24-Defrost is terminated when relay K4 loses power. K4
can lose power two ways.
1) If defrost is not satisfied after 14 1 minutes, CMC1
(terminal OUT) internal relay contacts open, K4 is de-
energized and defrost is terminated.
2) If S46 opens before 14 minutes has elapsed, K4
and K10 are de-energized and defrost is terminated.
To Next Page
Loading...
Need help?
General
