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D. Refrigerant Components:
1. Units shall have a sealed refrigerant circuit
including a highly efficient rotary compressor
(sizes 006 to 012), reciprocating compressor
(sizes 018 to 048), or scroll compressor (size
060) designed for heat pump operation.
2. Units shall have a capillary tube assembly for
refrigerant metering, an enhanced aluminum
lanced fin and rifled copper tube refrigerant
to air heat exchanger, a reversing valve, a
coaxial (tube-in-tube) refrigerant-to-water heat
exchanger.
3. Hermetic reciprocating compressors shall be
internally isolated. The compressor will be
mounted on isolating grommets. The grommets
will be secured to a heavy gage compressor
plate that has rubber grommet isolation from
the cabinet base. Compressor shall have ther-
mal overload protection and be located in an
insulated compartment away from airstream to
minimize sound transmission.
4. Refrigerant-to-air heat exchangers shall use
enhanced lanced aluminum fins and rifled
copper tube construction rated to withstand
450 psig refrigerant working pressure.
5. Refrigerant-to-water heat exchangers shall be of
copper inner-water tube and steel refrigerant
outer tube design, rated to withstand 450 psig
working refrigerant pressure and 450 psig
working water pressure. Plate-to-plate heat
exchangers cannot be used.
6. Refrigerant metering shall be accomplished by
capillary tube assembly only. Units intended for
use in standard operating range with entering
water temperatures from 60 to 95 F.
7. Reversing valves shall be four-way solenoid acti-
vated refrigerant valves, which shall fail to heat-
ing operation should the solenoid fail to
function. If the reversing valve solenoid fails to
cooling, a low temperature thermostat must be
provided to prevent over-cooling an already
cold room.
E. Drain Pan:
The drain pan shall be constructed to inhibit corro-
sion and be fully insulated. Drain outlet shall be
located on pan to allow complete and unobstructed
drainage of condensate. Vertical units will have a
factory-installed trap inside of cabinet. The standard
unit will have solid-state electronic condensate over-
flow protection. Mechanical float switches are not
acceptable.
F. Filter:
1. Units shall have a factory installed 1 in. wide fil-
ter bracket for filter removal from either side.
Units shall have a 1 in. thick throwaway type
fiberglass filter.
2. The contractor shall purchase one spare set of
filters and replace factory shipped filters on
completion of start-up.
3. Filters shall be standard sizes. If units use non-
standard filter sizes then the contractor shall
provide 12 spare filters for each unit.
4. Field-installed 2 in. filter brackets and 2 in.
fiberglass throwaway filters on all units can be
installed by contractor.
G. Controls and Safeties:
1. Electrical:
a. A control box shall be located within the unit
compressor compartment and shall contain a
50 va transformer, 24-volt activated, 2 or
3 pole compressor contactor, terminal block
for thermostat wiring and solid-state control-
ler for complete unit operation. Electro-
mechanical operation is not acceptable.
b. Units shall be nameplated for use with time-
delay fuses or HACR circuit breakers. Unit con-
trols shall be 24-volt and provide heating or
cooling as required by the remote thermostat/
sensor.
2. Piping:
a. Supply and return water connections shall
be copper FPT fittings and shall be securely
mounted flush to the cabinet corner post
allowing for connection to a flexible hose
without the use of a back-up wrench.
b. All water connections and electrical knock-
outs must be in the compressor compart-
ment corner post as to not interfere with the
serviceability of unit. Contractor shall be
responsible for any extra costs involved in
the installation of units that do not have this
feature.
3. Unit Controls:
a. Safety controls including a high-pressure
switch, a low-pressure sensor, and a low
water and low air temperature sensor.
Access fittings shall be factory installed on
high and low pressure refrigerant lines to
facilitate field service.
b. Activation of any safety device shall prevent
compressor operation via a lockout device.
The lockout shall be reset at the thermostat
or at the contractor-supplied disconnect
switch.
c. Units which may be reset only at the discon-
nect switch only shall not be acceptable.
