34
7.0 COMPONENTS & CONTROLS
7.10 Thermal Expansion Valve (TXV)
While scroll compressors usually do not require
FUDQNFDVHKHDWHUVWKHUHDUHLQVWDQFHVZKHQD
heater should be added. Refrigerant migration
during the off cycle can result in a noisy start up.
$GGDFUDQNFDVHKHDWHUWRPLQLPL]HUHIULJHUDWLRQ
migration, and to help eliminate any start up noise
RUEHDULQJ´ZDVKRXWµ
NOTE:
7KHLQVWDOODWLRQRIDFUDQNFDVHKHDWHU
is recommended if the system charge exceeds
WKHYDOXHVLQWKHWDEOHEHORZWRQPRGHOV
FRPHZLWKDFUDQNFDVHKHDWHUIDFWRU\LQVWDOOHGDV
LQGLFDWHGE\DQDVWHULVN
$FUDQNFDVHKHDWHULVWREHORFDWHGQHDUWKH
bottom of the compressor shell. Its purpose is
to drive refrigerant from the compressor shell
during long cycles, thus preventing damage to the
compressor during start-up.
$WLQLWLDOVWDUWXSRUDIWHUH[WHQGHGVKXWGRZQ
SHULRGVPDNHVXUHWKHKHDWHULVHQHUJL]HGIRUDW
least 12 hours before the compressor is started.
'LVFRQQHFWVZLWFKRQDQGZDOOWKHUPRVWDWRII
7.11 Compressor Crankcase Heater (CCH)
Components
$OOPRGHOVDUHHTXLSSHGZLWKDSURSHUO\VL]HGWKHU
-
PDOH[SDQVLRQYDOYH7;9WRPHWHUWKHUHIULJHUDQW
ÁRZDQGSURYLGHDFRQVLVWHQWVXSHUKHDWOHYHOLQWKH
KHDWLQJPRGH7KH7;9·VDOOKDYHDQLQWHUQDOFKHFN
valve that opens in the cooling mode to provide
XQUHVWULFWHGÁRZ$OO7;9·VKDYHDEOHHGUDWH
to help eliminate “hammering” in the off cycle that
VRPHWLPHVRFFXUVZKHQQRQEOHHG7;9·VDUHXVHG
on both the indoor coil and outdoor heat pump unit.
MA
X
IMUM
SYSTEM
CHARGE
VALUES
Charge
Limit
Model
Compressor
Without
Size
Model
Number
Crankcase
Heater
*
24
3
6
4
8
60
ZPS21K
5
E-PFV
ZPS
3
0K
5
E-PFV
ZPS40K
5
E-PFV
ZPS4
9
K
5
E-PFV
*
9
.6
lbs.
[4.
35
kg]
*9
.6
lbs.
[4.
35
kg]
*
12
lbs.
[
5
.44
kg]
*
12
lbs.
[
5
.44
kg]
*
Crankcase
heater
factory
installed.
7.12 High- and Low-Pressure Controls
7.13 Compressor Hard Start Components
6WDQGDUGRQDOOPRGHOV7KHVHFRQWUROVNHHSWKH
compressor from operating in pressure ranges
ZKLFKFDQFDXVHGDPDJHWRWKHFRPSUHVVRU%RWK
FRQWUROVDUHLQWKHORZYROWDJHFRQWUROFLUFXLW
The high-pressure control (HPC) is an automatic-
UHVHWZKLFKRSHQVQHDU36,*>N3D@DQG
FORVHVQHDU36,*>N3D@
7KHORZSUHVVXUHFRQWURO/3&LVDQDXWRPDWLF
UHVHWZKLFKRSHQVQHDU36,*>N3D@DQG
FORVHVQHDU36,*>N3D@
CAUTION:
The compressor has an
internal overload protector. Under some conditions,
LWFDQWDNHXSWRKRXUVIRUWKLVRYHUORDGWRUHVHW
0DNHVXUHRYHUORDGKDVKDGWLPHWRUHVHWEHIRUH
condemning the compressor.
6WDUWFRPSRQHQWVDUHQRWXVXDOO\UHTXLUHGZLWK
the scroll compressors used in heat pumps, but
DUHDYDLODEOHIRUVSHFLDOFDVHVDQGZKHUHVWDUW
components are desirable to reduce light dimming.
Hard start components must be field installed and
are available through Rheem Parts or Ruud Parts.
