4
EMI Products are subject to ongoing development.
Products & Specifications may change without notice.
C
ONDENSER
O
PERATION
The transformer located in the condensing unit pro-
vides 24v control power to both the condenser (outdoor unit)
and the evaporator (indoor unit). The 24v power supply can
be measured across terminals R and C.
NOTE:
Follow supplied wiring diagram exactly.
If you plan to upgrade (i.e., add electric heat)
the system in the future, it is important to install
wiring with the correct amperage rating for
the upgrade.
INTERCONNECT TUBING
Use the following guidelines when running suction
and liquid lines.
Maximum tubing run of 100 feet, including 35
feet of lift
(see EMI Policy Bulletin).
DO NOT
change tubing set size, no matter how long
the run/lift. This is important for proper compressor
oil return. Tubing size is documented in all
Specifica-
tion Sheets
.
NOTE:
Use of improper tubing sizes will void
the units warranty.
Always insulate the suction (gas) line. DO NOT in-
sulate the liquid line. The expansion device is in the
evaporator.
Tubing should be run as short and direct as possible.
To avoid oil trapping, tubing should be routed neatly
without any dips in the horizontal runs. Horizontal
suction lines should be pitched down in the direction
of flow with a drop of at least 1/2 per 10 to aid oil
flow.
Install a liquid line filter drier in interconnecting tub-
ing (if not standard). Position it as close to the con-
densing unit as possible. Filter must be a
bi-flow
type
if installed in a heat pump system (see Installing Fil-
ter Driers in this guide).
EMI recommends installation of P-traps in suction
(gas) line vertical lifts (35 max.) at the base, at 15
intervals, and at the top of the tubing run.
P-
TRAP
I
NSTALLATION
P
ROCEDURE
Any vertical suction (gas) line riser taller than 4
should have a P-trap installed at the base to facilitate
oil return when the condenser is above the evaporator
(Fig. 1).
When the evaporator is installed above the compres-
sor, the trap will prevent the flow of liquid back to the
compressor in the off cycle.
NOTE:
Avoid excessive oil buildup. The P-trap
should have a shallow depth and a short
horizontal section.
Prefabricated wrought copper traps are available from
your local refrigeration supply warehouse. You may
fabricate one using 2 street elbows and 1 standard
elbow.
P-traps are not required at the foot of the hot gas
risers due to increased oil flow at higher temperatures.
Long vertical risers in suction (gas) lines require
additional traps at the 15 level.
INSTALLING FILTER DRIERS
EMI installs standard filter driers in all 9, 12, and 15
BTU/h systems that utilize rotary compressor technol-
ogy (straight cool and heat pump).
Always install a new filter drier whenever the sys-
tem is open for repairs. Make sure to align the arrow
on the liquid line drier with the flow direction for the
unit. Use a bi-flow drier for heat pump installation.
NOTE:
An additional refrigerant charge will
be necessary to compensate for the new filter
drier. Check drier specifications for charge
recommendations.
ANTI-SHORT CYCLE TIMER (ASCT)
Anti-short cycle timer (ASCT) is standard on most
EMI models. It is also available in kit form as necessary.
Consult the factory for the latest information on ASCT.
LOW AMBIENT OPTIONS
Factory installed on heat pump only. Field installed
kit available for cooling only. Components include:
Fan cycle switch and crank case heater (09 ,12, 15)
Fan cycle switch only (18 and up)
Cooling Only-
The low ambient option is intended
for use on systems that operate in cooling mode at outdoor
temperatures below 60° F.
Single compressor units utilize a cycling condenser
(Figure 1)
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