Liebert Challenger Plus CP20A U Technical Data Manual page 14

Challenger Plus - Technical Data Manual
Stan dard fea tures - DX mod els (con tin ued)
Air cooled only
Liquid receiver
A welded steel liq uid re ceiver is pro vided to main tain
con stant and even re frig er ant flow to the ex pan sion valve, in
all cir cum stances. Shut- off valves are in stalled as stan dard on
the in let and out let of the re ceiver to as sist main te nance of the
cir cuit, if re quired.
A suita bly rated pres sure re lief valve is in stalled on the liq uid
re ceiver. The valve is equipped with a threaded con nec tion to
al low the re frig er ant to be dis charged out side of the
con di tioned space.
Air cooled condenser
A match ing Lie bert air cooled con denser with fan speed
con trol should be or dered with the unit. De tails of the
con dens ers are pro vided in this man ual, full de tails of all
con dens ers for all out door am bi ents are avail able in the
Con denser Tech ni cal Data Man ual, (P/N SLE CD TDM).
Note: The suggested condenser selections/performances for
each outdoor ambient are based on calculated data. The
actual selection of a condenser should always be verified on
the basis of the specific working conditions on each site.
Water cooled/freecooling units only
Plate heat exchanger
All wa ter cooled units (mod els W, H, F) are fit ted with a
brazed plate heat ex chang ers made of stain less steel. This
type of con denser is de signed for high ef fi ciency heat
ex change. The con denser is in ten tion ally over sized for the
ap pli ca tion to re duce pres sure drops (and the en ergy
con sump tion of the cir culation pump) in the wa ter sup ply and
thus al low the unit to op er ate with an ex ter nal wa ter cooler in
a closed cir cuit at high out door tem pera tures. Pres sure re lief
valves are fit ted down stream of the con denser. The valve is
equipped with a threaded con nec tion to al low the re frig er ant
to be dis charged out side of the con di tioned space.
Wa ter cooled units can op er ate with mains wa ter, cool ing
tower wa ter or wa ter in a closed cir cuit with an ex ter nal
dry cooler. Free cool ing units op er ate with wa ter in a closed
cir cuit from an ex ter nal dry cooler only.
When op er at ing in a closed cir cuit, it may be nec es sary
(de pend ing on out side tem pera tures) to add mono eth yl ene
gly col to pre vent the wa ter freez ing in win ter , re fer to the unit
In stal la tion Man ual for ap pli ca ble per cent ages.
A pump is used to cir cu late wa ter (wa ter/gly col) through the
unit (it is not sup plied).
If mains wa ter or tower wa ter is used, it is rec om mended to fit
a me chani cal fil ter on the wa ter line to pro tect the con denser
against pos si ble im pu ri ties con tained in the wa ter (for
con denser clean ing, re fer to the In stal la tion Man ual).
10
Drycooler
A dry cooler can be sup plied, if re quired. Full de tails of all
dry cool ers are avail able in the Dry cooler Tech ni cal Data
Man ual, P/N SLE DC TDM.
Head pressure control valve
Head pres sure op er ated regu lat ing valves ac cu rately con trol
the con dens ing tem pera ture and sys tem ca pac ity for vari ous
en ter ing fluid tem pera tures. A 2- way head pres sure con trol
valve is fit ted as stan dard on wa ter/gly col cooled, dual source
wa ter cooled and free cool ing units.
The valve con trols the con dens ing pres sure by regu lat ing the
wa ter flow to the plate con denser. It is in stalled at the
con denser out let with the pres sure probe po si tioned on the
re frig er ant dis charge line. It is auto mati cally closed when the
com pres sor is not op er at ing. It is sized for in let wa ter flow
tem pera tures lower than 17
pres sure drops.
For higher wa ter in let tem pera tures, higher wa ter flowrates
are re quired and pos si bly spe cial wa ter regu lat ing valves,
con sult Lie bert Ap pli ca tions En gi neers for de tails.
Freecooling only
Freecooling coil
The Freecooling coil is lo cated on the re turn air side of the
evapo ra tor coil. Wa ter/gly col flow to the coil is con trolled by
a pre-piped 2- way modu lat ing motorised valve. When
sup plied with a coolant so lu tion of suf fi ciently low
tem pera ture, the coil is suf fi ciently sized to of fer an equal
cool ing ca pac ity to that ob tained us ing the re frig era tion
cir cuit. The coil is tested to 30 Bar.
2-way control valve
As the out door am bi ent drops to a suf fi ciently low
tem pera ture, the 2- way mo tor ised valve modu lates the flow
to the coil, as in a chilled wa ter sys tem. The valve in cludes an
op er at ing link age and elec tric mo tor.
0
C re sult ing in low water- side
SLE CP TDM E.1 (06/99)